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ITTO-FMBIDENR FINAL PROJECT REPORT PD 5/93 Rev. I(F)

TEN-YEAR PRODUCTION OF TREATED RESIDUAL DIPTEROCARP

FOREST STANDS

FOREST MANAGEMENT BUREAU Department of Environment and Natural Resources

Visayas Avenue, Diliman, Quezon City

December 1995

ITTO-FMBIDENR FINAL PROJECT REPORT PD 5/93 Rev. I(F)

TEN-YEAR PRODUCTION OF TREATED RESIDUAL DIPTEROCARP

FOREST STANDS

FOREST MANAGEMENT BUREAU Department of Environment and Natural Resources

Visayas Avenue, Diliman, Quezon City

December 1995

I I I I

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 REVIEW OF LITERATURE

3.0 MATERIALS AND METHODS

4.0 RESULTS AND DISCUSSIONS

4.1 TSI REMOVALS OR MATERIALS

4.2 STAND COMPOSITION

4.3 STAND STRUCTURE

4.4 BASAL AREA

4.5 VOLUME

4.6 GROWTH INCREMENT

4.7 TREE MORTALITY AND INGROWTH

4.8 ECONOMIC PRODUCTION OF THE STUDY AREAS

4.8.1 REVENUE

4.8.2 COSTS AND PRICES

4.8.3 ECONOMIC CRITERIA

4.8.4 SENSITIVITY ANALYSIS

5.0 CONCLUSIONS AND RECOMMENDATIONS

REFERENCES

APPENDICES

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29-44

TABLE OF CONTENTS

1.0 INTRODUCTION

2.0 REVIEW OF LITERATURE

3.0 MATERIALS AND METHODS

4.0 RESULTS AND DISCUSSIONS

4.1 TSI REMOVALS OR MATERIALS

4.2 STAND COMPOSITION

4.3 STAND STRUCTURE

4.4 BASAL AREA

4.5 VOLUME

4.6 GROWTH INCREMENT

4.7 TREE MORTALITY AND INGROWTH

4.8 ECONOMIC PRODUCTION OF THE STUDY AREAS

4.8.1 REVENUE

4.8.2 COSTS AND PRICES

4.8.3 ECONOMIC CRITERIA

4.8.4 SENSITIVITY ANALYSIS

5.0 CONCLUSIONS AND RECOMMENDATIONS

REFERENCES

APPENDICES

PAGE

1

2

3

7

8

11

14

15

16

18

20

21

21

23

23

24

27

29-44

ITTO-FMB/DENR FINAL PROJECT REPORT PD 5/93 Rev. 1(F)

TEN-YEAR PRODUCTION OF TREATED RESIDUAL DIPTEROCARP FOREST STANDS

1.0 Introduction

The destruction and deterioration of the natural forest, paricularly the dipterocarp forest, has reached alarming proportions. As shown in the Philippine Forestry Statistics (1993), the forest cover has decreased to only 5.79 million hectares or 19.29% of the country's land area. Of this total, only 0.80 million hectares or roughly 2.68% comprised the remaining old-growth (virgin) forest, while 3.04 million hectares or 10.14% are residual or logged-over forest.

With the closure or cessation of commercial logging operations in the old­growth forest on January 01, 1992 as prescribed under DENR Administrative Order No. 24, series of 1991, the wood industry sector eventually return to the residual forest for the next cyclic cut. Understandably, the harvest on secondary forest will be much less than the virgin stands and therefore, it must be complemented from tree plantations and wood imports that are coupled with prohibitive costs.

One of the timber management strategies as advocated by forestry experts is the revitalization of forest renewal activities that would increase or improve the growth dynamics of logged-over forest for sustained-yield production, and at the same time, meet the increasing demands for domestic wood consumption. Timber Stand Improvement or TSI has been considered as one of the most critically-needed phase in selective logging implementation insofar as timely renewal of the dipterocarp forest is concerned (Reyes 1978, Revilla 1979, Weidelt and Banaag 1982, Tomboc 1987, Manila 1989).

Forest production as used in this paper refers to the changes or development in the average number of trees, composition, mean diameter, basal area and volume per hectare, including the economic feasibility of TSI operations after ten years from treatments. Theoretical considerations indicate that biological effects of TSI on preferred trees are likely not to last long due· to invading pioneers and climbing vineslbamboos as well as the expanding crowns of selected trees at certain point in time. Like the thinning operations in even-aged stands, the TSI activity in uneven-aged residual dipterocarp stands may have to be conducted in a series to continuously relieve adverse competition until a few years before the cutting cycle is reached.

This suggests that the interim TSI guidelines formulated in the early sixties (Reyes and Tagudar, 1964), which were incorporated in the selective logging prescriptions (Siapno, 1970) and the BFD Circular No. 32, series of 1981, will undergo further refinement since both guides assumed only one major TSI operations within

ITTO-FMB/DENR FINAL PROJECT REPORT PD 5/93 Rev. 1(F)

TEN-YEAR PRODUCTION OF TREATED RESIDUAL DIPTEROCARP FOREST STANDS

1.0 Introduction

The destruction and deterioration of the natural forest, paricularly the dipterocarp forest, has reached alarming proportions. As shown in the Philippine Forestry Statistics (1993), the forest cover has decreased to only 5.79 million hectares or 19.29% of the country's land area. Of this total, only 0.80 million hectares or roughly 2.68% comprised the remaining old-growth (virgin) forest, while 3.04 million hectares or 10.14% are residual or logged-over forest.

With the closure or cessation of commercial logging operations in the old­growth forest on January 01, 1992 as prescribed under DENR Administrative Order No. 24, series of 1991, the wood industry sector eventually return to the residual forest for the next cyclic cut. Understandably, the harvest on secondary forest will be much less than the virgin stands and therefore, it must be complemented from tree plantations and wood imports that are coupled with prohibitive costs.

One of the timber management strategies as advocated by forestry experts is the revitalization of forest renewal activities that would increase or improve the growth dynamics of logged-over forest for sustained-yield production, and at the same time, meet the increasing demands for domestic wood consumption. Timber Stand Improvement or TSI has been considered as one of the most critically-needed phase in selective logging implementation insofar as timely renewal of the dipterocarp forest is concerned (Reyes 1978, Revilla 1979, Weidelt and Banaag 1982, Tomboc 1987, Manila 1989).

Forest production as used in this paper refers to the changes or development in the average number of trees, composition, mean diameter, basal area and volume per hectare, including the economic feasibility of TSI operations after ten years from treatments. Theoretical considerations indicate that biological effects of TSI on preferred trees are likely not to last long due· to invading pioneers and climbing vineslbamboos as well as the expanding crowns of selected trees at certain point in time. Like the thinning operations in even-aged stands, the TSI activity in uneven-aged residual dipterocarp stands may have to be conducted in a series to continuously relieve adverse competition until a few years before the cutting cycle is reached.

This suggests that the interim TSI guidelines formulated in the early sixties (Reyes and Tagudar, 1964), which were incorporated in the selective logging prescriptions (Siapno, 1970) and the BFD Circular No. 32, series of 1981, will undergo further refinement since both guides assumed only one major TSI operations within

the cutting cycle. Hence, it is indispensable to obtain information needed for understanding the growth dynamics and economic production of treated residual dipterocarp stands that are ultimately useful in generating operational silvicultural prescriptions for secondary forest in the Philippines.

2.0 Review of Literature

Timber stand Improvement (TSI) is a silvicultural treatment being applied with some modifications or variations in 5 - 15 years old residual rainforests. The basic procedure involved is the removal through girdling or cutting of the undesirable or unwanted trees and other competitors directly affecting the healthy trees or Potential Crop Trees (PCTs), thereby enhancing the growth of the selected trees in particular and the residual stands in general, through additional growing space and favorable site factors (Manila and Woell1985, Manila 1989).

Research results from few TSI experiments in the country have shown its efficacy in forest renewal activities, although it is unfortunate that TSI has not been widely implemented in the field. This is because of the very little effort devoted by concerned government and private agencies regarding studies on growth dynamics of treated dipterocarp forest and its profitable operations. However, from these few experiments conducted locally there have. been appreciable successes to show the beneficial biological effects of TSI on residual stands. In fact, there was that pioneer study conducted with the Aras-asan Timber Company (Artimco) concession in Cagwait, Surigao del Sur, that became the foundation of TSI guides and later incorporated in the Handbook of Selective Logging in the Philippines (Utleg and Reyes 1967).

Other pilot studies to confirm the favorable effects of silvicultural treatments were undertaken in Bislig Bay Logging Comppany (now the PICOP Resources, Inc.), Surigao del Sur (Tagudar 1967), Nasipit Lumber Company (NALCO), Butuan City (Mauricio 1967), Paper Industries Corporation of the Philippines (now PRI), Bislig, Surigao del Sur (Domingo 1979 and 1982) and in Davao region (Weidelt and Banaag 1982). Likewise, there were enrichment planting studies on dipterocarp residual stands conducted in PRI concession by Tagudar (1979) and in Surigao Development Corporation (Sudecor), Carmen, Surigao del Sur (Uebelhoer, et. al. 1991). Likewise, the Forest Research Institute (now the Ecosystems Research and Development Bureau) had established a number of TSI plots within selected timber concession areas in the country (Mauricio 1980).

Furthermore, studies on the economic aspects or profitable operation of TSI in the Philippine residual dipterocarp forest are also scanty. More often than not, the third phase of selective logging system has been overlooked by timber license holders despite its standing requirement for field implementation by the government. On the other hand, the indifference of timber companies can be attributed to the specific provision setforth in the guidelines where non-utilization of TSI materials be followed strictly, and hence, it is viewed as an expensive operation, i.e. without immediate revenue whatsoever (Domingo, 1982).

2

the cutting cycle. Hence, it is indispensable to obtain information needed for understanding the growth dynamics and economic production of treated residual dipterocarp stands that are ultimately useful in generating operational silvicultural prescriptions for secondary forest in the Philippines.

2.0 Review of Literature

Timber stand Improvement (TSI) is a silvicultural treatment being applied with some modifications or variations in 5 - 15 years old residual rainforests. The basic procedure involved is the removal through girdling or cutting of the undesirable or unwanted trees and other competitors directly affecting the healthy trees or Potential Crop Trees (PCTs), thereby enhancing the growth of the selected trees in particular and the residual stands in general, through additional growing space and favorable site factors (Manila and Woell1985, Manila 1989).

Research results from few TSI experiments in the country have shown its efficacy in forest renewal activities, although it is unfortunate that TSI has not been widely implemented in the field. This is because of the very little effort devoted by concerned government and private agencies regarding studies on growth dynamics of treated dipterocarp forest and its profitable operations. However, from these few experiments conducted locally there have. been appreciable successes to show the beneficial biological effects of TSI on residual stands. In fact, there was that pioneer study conducted with the Aras-asan Timber Company (Artimco) concession in Cagwait, Surigao del Sur, that became the foundation of TSI guides and later incorporated in the Handbook of Selective Logging in the Philippines (Utleg and Reyes 1967).

Other pilot studies to confirm the favorable effects of silvicultural treatments were undertaken in Bislig Bay Logging Comppany (now the PICOP Resources, Inc.), Surigao del Sur (Tagudar 1967), Nasipit Lumber Company (NALCO), Butuan City (Mauricio 1967), Paper Industries Corporation of the Philippines (now PRI), Bislig, Surigao del Sur (Domingo 1979 and 1982) and in Davao region (Weidelt and Banaag 1982). Likewise, there were enrichment planting studies on dipterocarp residual stands conducted in PRI concession by Tagudar (1979) and in Surigao Development Corporation (Sudecor), Carmen, Surigao del Sur (Uebelhoer, et. al. 1991). Likewise, the Forest Research Institute (now the Ecosystems Research and Development Bureau) had established a number of TSI plots within selected timber concession areas in the country (Mauricio 1980).

Furthermore, studies on the economic aspects or profitable operation of TSI in the Philippine residual dipterocarp forest are also scanty. More often than not, the third phase of selective logging system has been overlooked by timber license holders despite its standing requirement for field implementation by the government. On the other hand, the indifference of timber companies can be attributed to the specific provision setforth in the guidelines where non-utilization of TSI materials be followed strictly, and hence, it is viewed as an expensive operation, i.e. without immediate revenue whatsoever (Domingo, 1982).

2

Cruz (1982) found only one out of three timber licensees to operate at profitable level following the classical TSI guides. She obtained a B/C ratio of 1.43 or an equivalent present net worth (PNW) ofP20.6 per hectare, while the two other firms had BCR values less than unity.

In view of dwindling wood supply and critical energy situation in the country, alternative proposition to mechanically utilize TSI materials or removals had been brought forward based on the following premises. First, an improvement or increase in yield in the next cyclic cut can be provided with additional growing space and favorable site factors. Second, the cost incurred in TSI operations can be realized

.. .immediately, so long as the harvesting activity is held at an economic level, or at least break-even point. Third, the extracted materials can serve as additional inputs to the mills, especially beneficial to wood-based industries with raw materials shortage (Veracion, 1987).

Faustino and Bascug (1977) reported that TSI operation by improvement cutting was worth undertaking in natural stand of Binuang (Octomeles sumatrana) since the average cost per hectare was very low. In using the TSI PICOP scheme, the BCR analyses yielded values greater than unity for all logging methods used, such as Koller K 300, Clark Ranger 668, Timberjack 404 and carabaolmanual method (Domingo, 1982). Likewise, Veracion (1987) obtained a BCR of 1.06 or an equivalent of Net Present Value (NPV) of P350.30 per hectare following the "modified TSI" method of PI COP.

The quantity of wood volume harvestable out of TSI removals averaged 78 cubic meters per hectare in PICOP CV eracion, 1987), 25-50 cu. m per hectare (net volume) in Great Pacific Timber and Development Corporation, Zamboanga City and Anakan Lumber Company, Gingoog City (Weigelt, et. aI., 1987) and 50 cu. m per hectare in Nasipit Lumber Company, Butuan City (Abraham, 1982). In Davao region, an average net volume of 65 cu. m per hectare can be utilized in TSI operations (Weidelt and Banaag, 1982).

These TSI materials or removals can be graded and used either for fish-box making, lumber, fuelwood or electric post, and thereby served as incentives to economically-oriented timber companies. It is worth mentioning, however, that the TSI extraction procedures should be closely supervised to forestall re-logging activities (Manila and Woell, 1985).

3.0 Materials and Methods

The TSI study sites are geographically located in four timber concessions or working units, representing four (4) important regions of the country, where substantial residual dipterocarp stands are still intact. The relative location of the study sites is shown in Figure I. These sites have elevations ranging from 250 to 850 meters above sea level and were logged more than ten (10) years ago. The years that elapsed

3

Cruz (1982) found only one out of three timber licensees to operate at profitable level following the classical TSI guides. She obtained a B/C ratio of 1.43 or an equivalent present net worth (PNW) ofP20.6 per hectare, while the two other firms had BCR values less than unity.

In view of dwindling wood supply and critical energy situation in the country, alternative proposition to mechanically utilize TSI materials or removals had been brought forward based on the following premises. First, an improvement or increase in yield in the next cyclic cut can be provided with additional growing space and favorable site factors. Second, the cost incurred in TSI operations can be realized

.. .immediately, so long as the harvesting activity is held at an economic level, or at least break-even point. Third, the extracted materials can serve as additional inputs to the mills, especially beneficial to wood-based industries with raw materials shortage (Veracion, 1987).

Faustino and Bascug (1977) reported that TSI operation by improvement cutting was worth undertaking in natural stand of Binuang (Octomeles sumatrana) since the average cost per hectare was very low. In using the TSI PICOP scheme, the BCR analyses yielded values greater than unity for all logging methods used, such as Koller K 300, Clark Ranger 668, Timberjack 404 and carabaolmanual method (Domingo, 1982). Likewise, Veracion (1987) obtained a BCR of 1.06 or an equivalent of Net Present Value (NPV) of P350.30 per hectare following the "modified TSI" method of PI COP.

The quantity of wood volume harvestable out of TSI removals averaged 78 cubic meters per hectare in PICOP CV eracion, 1987), 25-50 cu. m per hectare (net volume) in Great Pacific Timber and Development Corporation, Zamboanga City and Anakan Lumber Company, Gingoog City (Weigelt, et. aI., 1987) and 50 cu. m per hectare in Nasipit Lumber Company, Butuan City (Abraham, 1982). In Davao region, an average net volume of 65 cu. m per hectare can be utilized in TSI operations (Weidelt and Banaag, 1982).

These TSI materials or removals can be graded and used either for fish-box making, lumber, fuelwood or electric post, and thereby served as incentives to economically-oriented timber companies. It is worth mentioning, however, that the TSI extraction procedures should be closely supervised to forestall re-logging activities (Manila and Woell, 1985).

3.0 Materials and Methods

The TSI study sites are geographically located in four timber concessions or working units, representing four (4) important regions of the country, where substantial residual dipterocarp stands are still intact. The relative location of the study sites is shown in Figure I. These sites have elevations ranging from 250 to 850 meters above sea level and were logged more than ten (10) years ago. The years that elapsed

3

after logging (YEAL) actually correspond to the forest stand ages at the time of TSI plot establishment.

A brief description of the study sites is shown below:

a. Acoje Mining Company, Lucapon, Sta. Cruz, Zambales 22-year old residual stand, logged in 1960 450 meters elevation Soil type/series - Undifferentiated Mountain Soils 2,643.8 mm annual rainfall (1975-1987) Region No.3, Climatic Type 1 Main Dipterocarps :Apitong ( Dipterocarpus grandiflorus)

Tanguile (Shorea polvsperma) Non-dipterocarps: Makaasim (Syzvgium nitidum) and Miscellaneous spp. First TSI: 217 trees per hectare removed, or 11 % of the Treatments: original residual stand, equivalent to 6.91 sq.m. per

hectare (18% removals) or equal to 77.2 cU.m. per hectare (32% removals)

b. Surigao Development Corporation, Carmen, Surigao del Sur 13-year old residual stand, logged in 1964 450 meters elevation Soil type/series - Kabatohan Clay Loam 5,026.2 mm annual rainfall (1951-1983) Region No. 11, Climatic Type 2 Main Dipterocarp: Red lauan (Shorea negrosensis) and

Bagtikan (Shorea plicata) Non-dipterocarps: Putian (Alangium meveri() and Miscellaneous spp. First TSI : 346 trees per hectare removed, or 18% of the Treatments original stand, equivqlent to 10.6 sq.m. per hectare (34%

removals) or equal to 90.2 cU.m. per hectare (32% removals).

c. Taggat Industries, Inc., Calanasan, Kalinga-Apayao 17 -year old residual stand, logged in 1965 250 meters elevation Soil type/series - Undifferentiated Mountain Soils 4,233.2 mm annual rainfal1(1951-1983) Region No. 2, Climatic Type No. 3 Main Dipterocarps:Red lauan (Shorea negrosensis) and

Tanguile (Shorea polvsperma) Non-dipterocarps: Ulayan (Lithocarpus llanosiij and Miscellaneous spp. First TSI: 220 trees per hectare removed, or 10% ofthe original Treatments: stand, or equivalent to 5.22 sq.m. per hectare (20%

removals) or 67.4 cU.m. per hectare (24% removals).

4

after logging (YEAL) actually correspond to the forest stand ages at the time of TSI plot establishment.

A brief description of the study sites is shown below:

a. Acoje Mining Company, Lucapon, Sta. Cruz, Zambales 22-year old residual stand, logged in 1960 450 meters elevation Soil type/series - Undifferentiated Mountain Soils 2,643.8 mm annual rainfall (1975-1987) Region No.3, Climatic Type 1 Main Dipterocarps :Apitong ( Dipterocarpus grandiflorus)

Tanguile (Shorea polvsperma) Non-dipterocarps: Makaasim (Syzvgium nitidum) and Miscellaneous spp. First TSI: 217 trees per hectare removed, or 11 % of the Treatments: original residual stand, equivalent to 6.91 sq.m. per

hectare (18% removals) or equal to 77.2 cU.m. per hectare (32% removals)

b. Surigao Development Corporation, Carmen, Surigao del Sur 13-year old residual stand, logged in 1964 450 meters elevation Soil type/series - Kabatohan Clay Loam 5,026.2 mm annual rainfall (1951-1983) Region No. 11, Climatic Type 2 Main Dipterocarp: Red lauan (Shorea negrosensis) and

Bagtikan (Shorea plicata) Non-dipterocarps: Putian (Alangium meveri() and Miscellaneous spp. First TSI : 346 trees per hectare removed, or 18% of the Treatments original stand, equivqlent to 10.6 sq.m. per hectare (34%

removals) or equal to 90.2 cU.m. per hectare (32% removals).

c. Taggat Industries, Inc., Calanasan, Kalinga-Apayao 17 -year old residual stand, logged in 1965 250 meters elevation Soil type/series - Undifferentiated Mountain Soils 4,233.2 mm annual rainfal1(1951-1983) Region No. 2, Climatic Type No. 3 Main Dipterocarps:Red lauan (Shorea negrosensis) and

Tanguile (Shorea polvsperma) Non-dipterocarps: Ulayan (Lithocarpus llanosiij and Miscellaneous spp. First TSI: 220 trees per hectare removed, or 10% ofthe original Treatments: stand, or equivalent to 5.22 sq.m. per hectare (20%

removals) or 67.4 cU.m. per hectare (24% removals).

4

d. Great Pacific Timber and Development Corporation, Upper Ayala, Zamboanga City 14-year old residual stand, logged in 1968 850 meters elevation Soil type/series - Maligaya Clay 2,816 mm annual rainfall (1971-1985) Region No. 9, Climatic Type 3 Main Dipterocarps:Mindanao White lauan (Shorea mindanensis) and

Tanguile (Shorea polvsperma) Non-dipterocarps: Hagimit (Ficus minahassae) and Miscellaneous spp. First TSI: 458 trees per hectare removed, or 24% of the original Treatments: stand, or equivalent to 10.1 sq.m. per hectare (32%

removals) or 99.3 cu.m. per hectare (37% removals).

The data on rainfall patterns covering the study sites are shown in Table 1. These information have been gathered from the National Institute of Climatology, P AG-ASA and from the recorded data using the standard raingauge established by the Philippine-German TSI Project.

Table 1. Mean monthly rainfall (mm) in the study areas.

Taggat A~oje Sudecor GPTDC Month 1951-1983 1975-1987 1951-1983 1971-1985 January 515.7 5.7 901.2 86.0 February 269.2 14.2 691.7 80.9 March 183.4 10.2 531.8 160.1 April 134.4 35.2 439.2 168.7 May 154.5 220.3 249.3 274.4 June 239.2 375.7 234.0 340.8 July 260.5 473.6 134.2 394.9

August 298.6 887.7 124.2 316.5 September 418.8 358.8 136.0 288.1 October 436.7 207.2 226.6 330.4

November 606.0 33.2 534.0 270.2 December 706.2 22.0 824.0 163.3

Total 4,233.2 2,643.8 5,026.2 2,816.3

The study plots within the residual stands are considered homogenous after calibration and comparison with regard to the stocking density, standing basal area and volume of trees in each site. The determination of the homogeneity of forest stand and the comparison between and among study sites were done by establishing a pair of TSI plots consisting of Treated and Control plots with a size of 0.5 ha. each in the four working units. From these permanent sample plots, twelve (12) subplots, 20 x 20 meters dimension, were demarcated and arranged to conform with the completely randomized design (CRD). Six (6) subplots were randomly established in each TSI plot. Thus, the treated and control plots served as the treatments for comparison in each site.

5

d. Great Pacific Timber and Development Corporation, Upper Ayala, Zamboanga City 14-year old residual stand, logged in 1968 850 meters elevation Soil type/series - Maligaya Clay 2,816 mm annual rainfall (1971-1985) Region No. 9, Climatic Type 3 Main Dipterocarps:Mindanao White lauan (Shorea mindanensis) and

Tanguile (Shorea polvsperma) Non-dipterocarps: Hagimit (Ficus minahassae) and Miscellaneous spp. First TSI: 458 trees per hectare removed, or 24% of the original Treatments: stand, or equivalent to 10.1 sq.m. per hectare (32%

removals) or 99.3 cu.m. per hectare (3 7% removals).

The data on rainfall patterns covering the study sites are shown in Table 1. These information have been gathered from the National Institute of Climatology, P AG-ASA and from the recorded data using the standard raingauge established by the Philippine-German TSI Project.

Table 1. Mean monthly rainfall (mm) in the study areas.

Taggat A~oje Sudecor GPTDC Month 1951-1983 1975-1987 1951-1983 1971-1985 January 515.7 5.7 901.2 86.0 February 269.2 14.2 691.7 80.9 March 183.4 10.2 531.8 160.1 April 134.4 35.2 439.2 168.7 May 154.5 220.3 249.3 274.4 June 239.2 375.7 234.0 340.8 July 260.5 473.6 134.2 394.9

August 298.6 887.7 124.2 316.5 September 418.8 358.8 136.0 288.1 October 436.7 207.2 226.6 330.4

November 606.0 33.2 534.0 270.2 December 706.2 22.0 824.0 163.3

Total 4,233.2 2,643.8 5,026.2 2,816.3

The study plots within the residual stands are considered homogenous after calibration and comparison with regard to the stocking density, standing basal area and volume of trees in each site. The determination of the homogeneity of forest stand and the comparison between and among study sites were done by establishing a pair of TSI plots consisting of Treated and Control plots with a size of 0.5 ha. each in the four working units. From these permanent sample plots, twelve (12) subplots, 20 x 20 meters dimension, were demarcated and arranged to conform with the completely randomized design (CRD). Six (6) subplots were randomly established in each TSI plot. Thus, the treated and control plots served as the treatments for comparison in each site.

5

In designated treated plots the criteria used in the removal of undesirable or unwanted trees are the following:

a. All defective, deformed and poorly-shaped trees were poison-girdled, with arboricides;

b. All trees that directly interfere or were expected to interfere with the crown region of the favored and valuable tree species during the next 10-15 years were removed. No tree was marked unless its removal would benefit at least one better residual or established regeneration of desired species; ,

c. Rubbing trees or those liable to damage the bole of selected crops by rubbing were eliminated; and

d. Vines and climbers were cut whenever they can be reached, except rattans.

In the collection and compilation of TSI data in both plots, the initial data or those collected after the treatments and the tenth-year remeasurements were used in the analyses of growth responses. The stand composition in terms of stocking density and species abundance expressed on a per hectare basis included all trees 5 cm diameter at breast height (dbh) and up, considering the recommended diameter range of PCTs from 5-40 centimeters.

The stand composition of each site was grouped into the treated and control plots, and classified into two (2) broad groups; the dipterocarps and non-dipterocarps . . The PCTs were also considered as a group to determine their share or contribution in the development of the forest stand.

The mean total heights of dominant and co-dominant trees at the establishment and tenth-year period were determined. Likewise, basal area and volume on a per hectare basis that included all trees 5 cm dbh and up were computed and analyzed. Mortality rate and ingrowths were recorded, analyzed and compared in both plots of each site. The annual growth increment in terms of diameter, basal area and volume of trees were calculated from the increase during the initial and after ten years period, and divided by the period of observation.

Moreover, the economic analyses ofTSI operations involved the determination of benefits received and the corresponding costs incurred. The tangible benefits obtained from TSI included the Revenues derived from the timber removed during treatments, the Growth Increment derived and the Incremental Yield at the end of the cutting cycle, when multiplied by the average market/selling price of logs, fuelwood and other wood products used within the vicinities of the project areas. On the other hand, the costs involved the TSI lab or/manpower, surveys, care and maintenance costs at different periods within the cutting cycle. Considering the costs incurred and benefits received that occurred at different points in time, in order to compare them, they were expressed as present values by discounting process. The formulae used are the Present Networth (PNW) and the Benefit Cost Ratio (BCR).

6

In designated treated plots the criteria used in the removal of undesirable or unwanted trees are the following:

a. All defective, deformed and poorly-shaped trees were poison-girdled, with arboricides;

b. All trees that directly interfere or were expected to interfere with the crown region of the favored and valuable tree species during the next 10-15 years were removed. No tree was marked unless its removal would benefit at least one better residual or established regeneration of desired species; ,

c. Rubbing trees or those liable to damage the bole of selected crops by rubbing were eliminated; and

d. Vines and climbers were cut whenever they can be reached, except rattans.

In the collection and compilation of TSI data in both plots, the initial data or those collected after the treatments and the tenth-year remeasurements were used in the analyses of growth responses. The stand composition in terms of stocking density and species abundance expressed on a per hectare basis included all trees 5 cm diameter at breast height (dbh) and up, considering the recommended diameter range of PCTs from 5-40 centimeters.

The stand composition of each site was grouped into the treated and control plots, and classified into two (2) broad groups; the dipterocarps and non-dipterocarps . . The PCTs were also considered as a group to determine their share or contribution in the development of the forest stand.

The mean total heights of dominant and co-dominant trees at the establishment and tenth-year period were determined. Likewise, basal area and volume on a per hectare basis that included all trees 5 cm dbh and up were computed and analyzed. Mortality rate and ingrowths were recorded, analyzed and compared in both plots of each site. The annual growth increment in terms of diameter, basal area and volume of trees were calculated from the increase during the initial and after ten years period, and divided by the period of observation.

Moreover, the economic analyses ofTSI operations involved the determination of benefits received and the corresponding costs incurred. The tangible benefits obtained from TSI included the Revenues derived from the timber removed during treatments, the Growth Increment derived and the Incremental Yield at the end of the cutting cycle, when multiplied by the average market/selling price of logs, fuelwood and other wood products used within the vicinities of the project areas. On the other hand, the costs involved the TSI lab or/manpower, surveys, care and maintenance costs at different periods within the cutting cycle. Considering the costs incurred and benefits received that occurred at different points in time, in order to compare them, they were expressed as present values by discounting process. The formulae used are the Present Networth (PNW) and the Benefit Cost Ratio (BCR).

6

Furthermore, sensitivity analysis was undertaken to determine the changes in values of PNW and BCR with the varying values of the factors of production, e.g. interest (discount) rates, cost overrun, decrease in yield (volume) of TSI materials and fall in product prices.

4.0 Results and Discussions

4.1 TSI Removals or Materials

The application of TSI treatments through girdling, cutting and/or poisoning of -- undesirable. trees found in designated treated plots of the study sites had accumulated

. substantial. quantity of wood raw materials or TSI removals. Table 2 presents the number of trees, basal area and volume of timber removed per hectare during the first TSI treatments in each study area.

The number of trees girdled or removed in the first TSI treatments covering the 13 to 22-year old residual dipterocarp stands averaged 310 trees per hectare, or equivalent to 68 dipterocarps and 242 non-dipterocarps. The corresponding gross basal area and volume of TSI removals were 8.22 sq.m and 83.5 cU.m per hectare, respectively.

Table 2. Timber removed per hectare at the first TSI treatments.

TSI DIPTEROCARPS NON-DIPTEROCARPS : ALL SPECIES

SITES Tree B.A. Vol. Tree B.A. Vol. Tree B.A. VoI. (no.) (m2) (m3) (no.) (m2) (m3) (no.) (m2) (m3)

Taggat 162 4.31 39.7 58 2.60 27.7 220 6.91 67.4

Acoje 25 2.60 50.0 192 2.62 27.2 217 5.22 77.4

Sudecor 54 0.26 2.2 292 10.36 88 346 10.62 90.2

GPTDC 33 0.22 1.4 425 9.90 97.9 458 10.12 99.3

Mean 68 1.25 23.3 242 6.37 60.2 310 8.22 83.5

Among the four working units, GPTDC had the most number of trees removed during TSI operations while Acoje had the least removals. Similarly, the number, basal area and volume of dipterocarps and non-dipterocarps removed from each TSI site is shown in Table 2. Except in Taggat, the proportions of removals comprised largely of non-dipterocarps in the forest stands of Sudecor, GPTDC and Acoje areas. It was only in Taggat site where exceptional stand composition of dipterocarps occurred, thereby the TSI materials comprised mostly of that group. Likewise, the quantity of available TSI materials varied from place to place such that the comparability of the plots at the time of establishment had to be ascertained.

Analysis of variance on the original residual dipterocarp forest stands relative to the number, basal area and volume of trees found within the plots before TSI treatments is presented in Appendix Tables 1, 2 and 3. Comparisons of the difference in the number of trees per hectare of the original residual stand were found not

7

Furthermore, sensitivity analysis was undertaken to determine the changes in values of PNW and BCR with the varying values of the factors of production, e.g. interest (discount) rates, cost overrun, decrease in yield (volume) of TSI materials and fall in product prices.

4.0 Results and Discussions

4.1 TSI Removals or Materials

The application of TSI treatments through girdling, cutting and/or poisoning of -- undesirable. trees found in designated treated plots of the study sites had accumulated . . substantial. quantity of wood raw materials or TSI removals. Table 2 presents the

number of trees, basal area and volume of timber removed per hectare during the first TSI treatments in each study area.

The number of trees girdled or removed in the first TSI treatments covering the 13 to 22-year old residual dipterocarp stands averaged 310 trees per hectare, or equivalent to 68 dipterocarps and 242 non-dipterocarps. The corresponding gross basal area and volume of TSI removals were 8.22 sq.m and 83.5 cU.m per hectare, respectively.

Table 2. Timber removed per hectare at the first TSI treatments.

TSI DIPTEROCARPS NON-DIPTEROCARPS : ALL SPECIES

SITES Tree B.A. Vol. Tree B.A. Vol. Tree B.A. Vol. (no.) (m2) (m3) (no.) (m2) (m3) (no.) (m2) (m3)

Taggat 162 4.31 39.7 58 2.60 27.7 220 6.91 67.4

Acoje 25 2.60 50.0 192 2.62 27.2 217 5.22 77.4

Sudecor 54 0.26 2.2 292 10.36 88 346 10.62 90.2

GPTDC 33 0.22 1.4 425 9.90 97.9 458 10.12 99.3

Mean 68 1.25 23.3 242 6.37 60.2 310 8.22 83.5

Among the four working units, GPTDC had the most number of trees removed during TSI operations while Acoje had the least removals. Similarly, the number, basal area and volume of dipterocarps and non-dipterocarps removed from each TSI site is shown in Table 2. Except in Taggat, the proportions of removals comprised largely of non-dipterocarps in the forest stands of Sudecor, GPTDC and Acoje areas. It was only in Taggat site where exceptional stand composition of dipterocarps occurred, thereby the TSI materials comprised mostly of that group. Likewise, the quantity of available TSI materials varied from place to place such that the comparability of the plots at the time of establishment had to be ascertained.

Analysis of variance on the original residual dipterocarp forest stands relative to the number, basal area and volume of trees found within the plots before TSI treatments is presented in Appendix Tables 1, 2 and 3. Comparisons of the difference in the number of trees per hectare of the original residual stand were found not

7

.......

significant between plots in Acoje and Taggat, but differed significantly in the number' of dipterocarps found in Sudecor and GPTDC areas. There were more dipterocarps in the treated plots of GPTDC and Sudecor sites. However, the difference in the average basal area and volume of trees per hectare before TSI treat'ments showed no significant variations between plots.

Further tests showed that the number of stems, basal area and volume density of the growing stock in all TSI sites were similar in both control and treated plots, after the application of the first TSI treatments (Appendix Tables 4, 9 and 13, respectively). In general, the residual forest stands of the study areas can be considered as homogenous after calibration and application of TSI. Any change in stand parameters or growth responses after TSI operations can, therefore, be attributed to the treatments and not on the stand differences at the beginning of the experiment.

A closer scrutiny of the analysis of variance on the number and basal area of trees found in GPTDC and Sudecor plots at the tenth-year growing period showed highly significant variations, as shown in Appendix Tables 5 and 10. It was inevitable that a second TSI treatments be carried out in the four wo~king units at that point in time, which were inputs to the economic analysis under Section 4.8 of this paper. The available TSI materials or removals per hectare in each study area is summarized in Table 3.

Table 3. Available TSI materials per hectare for the second treatments.

TSI DIPTEROCARPS NON-DIPTEROCARPS ALL SPECIES

SITES Tree B.A. Vol. Tree B.A. Vol. Tree B.A. Vol. (no.) (m2) (m3) (no.) (m2) (m3) (no.) (m2) (m3)

Taggat 52 9.34 37.6 28 4.25 18.8 80 13.59 56.4

Acoje 31 2.23 14.6 54 4.95 11.2 85 7.18 25.8

Sudecor 47 0.68 2.0 56 8.95 22.8 103 9.63 24.8

GPTDC 38 0.34 2.1 114 10.87 36.4 152 11.21 38.5

Mean 42 3.15 14.1 63 7.25 22.3 105 10.40 36.4

4.2 Stand Composition

An average of 1,821 trees composed the control plots while the treated plots had 1,685 trees per hectare at the initial year, and after ten years, the control plots had 1,965 trees while 2,155 trees per hectare comprised the treated plots of the study areas (Tables 4 and 5).

The difference in number of trees per hectare among study sites compared at the time of plot establishment and ten years thereafter was not significant between TSI plots (Appendix Table 6). However, comparisons of the difference in the number of stems in each study site after ten years showed GPTDC and Sudecor were highly significant, while the stocking. density in Taggat and Acoje sites had no significant vari~~~,on between plots (Appendix Table 5).

8

. ',.: ~. ; _ •. '.":: ". '.: .-" .~:;:"';:: ;"'.:-,,' ~~: -~. :-. " '~"'. 4'::' '; • <: . ~.~ . ." .', : ;. : .. ', :.-. :~: .••. ' -. .... -, .... .. :~.;; .. : .... :.,' >'.'::::~'.' .' .•...... :':. . ...... : .. : .. .", ';':"J:'

significant between plots in Acoje and Taggat, but differed significantly in the number' of dipterocarps found in Sudecor and GPTDC areas. There were more dipterocarps in the treated plots of GPTDC and Sudecor sites. However, the difference in the average basal area and volume of trees per hectare before TSI treat'ments showed no significant variations between plots.

Further tests showed that the number of stems, basal area and volume density of the growing stock in all TSI sites were similar in both control and treated plots, after the application of the first TSI treatments (Appendix Tables 4, 9 and 13, respectively). In general, the residual forest stands of the study areas can be considered as homogenous after calibration and application of TSI. Any change in stand parameters or growth responses after TSI operations can, therefore, be attributed to the treatments and not on the stand differences at the beginning of the experiment.

A closer scrutiny of the analysis of variance on the number and basal area of trees found in GPTDC and Sudecor plots at the tenth-year growing period showed highly significant variations, as shown in Appendix Tables 5 and 10. It was inevitable that a second TSI treatments be carried out in the four wo~king units at that point in time, which were inputs to the economic analysis under Section 4.8 of this paper. The available TSI materials or removals per hectare in each study area is summarized in Table 3.

Table 3. Available TSI materials per hectare for the second treatments.

TSI DIPTEROCARPS NON-DIPTEROCARPS ALL SPECIES

SITES Tree B.A. Vol. Tree B.A. Vol. Tree B.A. Vol. (no.) (m2) (m3) (no.) (m2) (m3) (no.) (m2) (m3)

Taggat 52 9.34 37.6 28 4.25 18.8 80 13.59 56.4

Acoje 31 2.23 14.6 54 4.95 11.2 85 7.18 25.8

Sudecor 47 0.68 2.0 56 8.95 22.8 103 9.63 24.8

GPTDC 38 0.34 2.1 114 10.87 36.4 152 11.21 38.5

Mean 42 3.15 14.1 63 7.25 22.3 105 10.40 36.4

4.2 Stand Composition

An average of 1,821 trees composed the control plots while the treated plots had 1,685 trees per hectare at the initial year, and after ten years, the control plots had 1,965 trees while 2,155 trees per hectare comprised the treated plots of the study areas (Tables 4 and 5).

The difference in number of trees per hectare among study sites compared at the time of plot establishment and ten years thereafter was not significant between TSI plots (Appendix Table 6). However, comparisons of the difference in the number of stems in each study site after ten years showed GPTDC and Sudecor were highly significant, while the stocking. density in Taggat and Acoje sites had no significant vari~~~,on between plots (Appendix Table 5).

8

.', .... . ',.: ~. _. ''.":: ". '.:.-'.~:;:"';::;"'.:''''~~:-~.:-.', '~"'. 4'::' '; • <: ... ,':.. .':.',.:.::. ,', :::. :~: : .:. ,";:'. '.-, ..... ::_.' .~.- .-;-. ,,:-;. ~.-' .:~.;;.', : .-.', ... :-, :'-.:.:: ":.':.'~'" . ' .•. ' ':.':': .' .... ~ .:. '.'.':: .' '';".-'-' .•.. : ..• '.:'J.:

Table 4. Composition of residual dipterocarp stands at establishment period.

LOCATION/SPECIES : TREATED PLOTS CONTROL PLOTS GROUPS Tree/Ha. : SO % Tree/Ha. : SO %

1. Taggat, R-2

Dipterocarps 1,379 32.7 69.3 1,225 27.4 61.0 Non-dipt. 612 13.0 30.7 783 15.4 39.0 All species 1,991 33.5 100.0 2,008 23.2 100.0

2. Acoje, R-3

Dipterocarps 392 8.4 23.1 467 10.2 22.6 Non-dipt. 1,304 19.8 76.9 1,596 18.7 77.4 All species 1,196 20.7 100.0 2,063 22.3 100.0

3. Sudecor, R-11

Dipterocarps 796 17.9 50.4 412 20.0 23.0 Non-dipt. 783 29.2 49.6 1,383 30.4 77.0 All species 1,579 20.7 100.0 1,795 33.3 100.0

4. GPTDC, R-9

Dipterocarps 629 14.6 42.6 371 12.8 26.2 Non-dipt. 846 12.9 57.4 1,046 15.8 73.8 All species 1,475 16.8 100.0 1,417 20.6 100.0

Mean 1,685 61.2 1,~21 75.5

Results showed that there was 28% increase, i.e. 1,685 to 2,155 trees, in the mean number of stems per hectare in treated plots as compared to 8% increase (1,821 to 1,965 trees) in plots without TSI treatments among study sites. This improvement in stocking density is attributed to additional growing space when competitor trees were removed in the course of TSI operations within designated treated plots.

Consequently, after a period of time favorable site factors became prevalent in treated plots such as higher quantities of average organic matter content, available phosphorous and exchangeable potassium in the soil layers and that more intense light penetrated through the crown canopies that influenced to a great extent the stand composition of the permanent sample plots (Manila, 1989). On the other hand, the untreated plots of the study areas responded with the least stocking levels composed mostly of non-dipterocarps or miscellaneous species above 5 cm dbh.

9

Table 4. Composition of residual dipterocarp stands at establishment period.

LOCATION/SPECIES : TREATED PLOTS CONTROL PLOTS GROUPS Tree/Ha. : SO % Tree/Ha. : SO %

1. Taggat, R-2

Dipterocarps 1,379 32.7 69.3 1,225 27.4 61.0 Non-dipt. 612 13.0 30.7 783 15.4 39.0 All species 1,991 33.5 100.0 2,008 23.2 100.0

2. Acoje, R-3

Dipterocarps 392 8.4 23.1 467 10.2 22.6 Non-dipt. 1,304 19.8 76.9 1,596 18.7 77.4 All species 1,196 20.7 100.0 2,063 22.3 100.0

3. Sudecor, R-11

Dipterocarps 796 17.9 50.4 412 20.0 23.0 Non-dipt. 783 29.2 49.6 1,383 30.4 77.0 All species 1,579 20.7 100.0 1,795 33.3 100.0

4. GPTDC, R-9

Dipterocarps 629 14.6 42.6 371 12.8 26.2 Non-dipt. 846 12.9 57.4 1,046 15.8 73.8 All species 1,475 16.8 100.0 1,417 20.6 100.0

Mean 1,685 61.2 1,a21 75.5

Results showed that there was 28% increase, i.e. 1,685 to 2,155 trees, in the mean number of stems per hectare in treated plots as compared to 8% increase (1,821 to 1,965 trees) in plots without TSI treatments among study sites. This improvement in stocking density is attributed to additional growing space when competitor trees were removed in the course of TSI operations within designated treated plots.

Consequently, after a period of time favorable site factors became prevalent in treated plots such as higher quantities of average organic matter content, available phosphorous and exchangeable potassium in the soil layers and that more intense light penetrated through the crown canopies that influenced to a great extent the stand composition of the permanent sample plots (Manila, 1989). On the other hand, the untreated plots of the study areas responded with the least stocking levels composed mostly ofnon-dipterocarps or miscellaneous species above 5 cm dbh.

9

Table 5. Composition of residual dipterocarp stand after ten years.

LOCATION/SPECIES TREATED PLOTS : CONTROL PLOTS GROUPS Tree/Ha. : SO % Tree/Ha. : SO %

1. Taggat, R-2 Dipterocarps 1,354 25.1 67.9 1,042 11.6 59.4 Non-dipt. 641 6.6 32.1 712 8.0 40.6 All species 1,995 27.5 100.0 1,754 12.9 100.0

2. Acoje, R-3 Dipterocarps 454 4.8 21.7 504 4.2 21.5 Non-dipt. 1,642 5.9 78.3 1,842 13.8 78.5 All species 2.096 9.4 100.0 2,346 14.6 100.0

3. Sudecor, R-11 Dipterocarps 1,233 11.2 47.6 562 10.9 27.8 Non-dipt. 1,358 22.7 52.4 1,458 17.3 72.2 All species 2,591 24.6 100.0 2,020 18.6 100.0

4. GPTDC, R-9 Dipterocarps 896 10.5 46.2 462 4.8 26.5 Non-dipt. 1,042 9.1 53.8 1,279 3.5 73.5 All species 1,938 12.7 100.0 1,741 7.3 100.0

Mean 2,155 71.6 1,965 68.2

In each study site, Taggat was found heavily stocked with dipterocarps in both plots at the initial" and tenth-year periods. While Acoje showed the least stocking of dipterocarps in the treated plots and GPTDC site had the lowest in the control plots. As mentioned earlier, the mean number of trees after ten years became statistically significant between plots of Sudecor and GPTDC , while Acoje and Taggat did not differ significantly (Appendix Table 5). That is, the dipterocarps found in plots with TSI treatments at Sudecor and GPTDC areas had higher increases in stocking density, as brought about by the preponderance of recruits (ingrowths) that graduated into the 5-cm dbh class, as compared to the untreated plots of other sites (please see Table 15).

Sudecor was heavily stocked with 2,591 trees per hectare in the treated plots and 2,020 trees in the control plots after ten years. While GPTDC had the least stocking among the study sites with 1,938 trees in plots with TSI treatments and 1,741 trees per hectare in the control plots (Table 5).

Out of the stand density, there was the abundance of non-dipterocarps in both plots of each site at establishment and tenth-year remeasurement periods, except in Taggat area where the dipterocarps predominated. Among the dipterocarps, Red lauan (Sltorea negrosensis) was the most abundant in both plots of Sudecor and Taggat sites, Mindanao White lauan (Sltorea mill dan ellsis) in GPTDC and Apitong (Dipterocarpus gralldiflorus) in Acoje concession during establishment and ten years after treatments . . 4,

10

.• '.'. . " '.' .,::. ::. ";'-, . ~:~-~ .. ;.: .. ~. ~'" ," .-, -., -,' . ",' :.. . ... ',.,... . .• >.~.;, , .. _,- " .. ~ .:" ';~'.:-~~":"" .~ .. :-,-,~:,' ~ :.: .. ~ ... ' ,', : ,.,.',', .-::-",:', ':"i. > :."', =. '.,.,' . -:- .' "'"';:':' ....... "-: -: 7.,: .".

Table 5. Composition of residual dipterocarp stand after ten years.

LOCATION/SPECIES TREATED PLOTS : CONTROL PLOTS GROUPS Tree/Ha. : SO % Tree/Ha. : SO %

1. Taggat, R-2 Dipterocarps 1,354 25.1 67.9 1,042 11.6 59.4 Non-dipt. 641 6.6 32.1 712 8.0 40.6 All species 1,995 27.5 100.0 1,754 12.9 100.0

2. Acoje, R-3 Dipterocarps 454 4.8 21.7 504 4.2 21.5 Non-dipt. 1,642 5.9 78.3 1,842 13.8 78.5 All species 2.096 9.4 100.0 2,346 14.6 100.0

3. Sudecor, R-11 Dipterocarps 1,233 11.2 47.6 562 10.9 27.8 Non-dipt. 1,358 22.7 52.4 1,458 17.3 72.2 All species 2,591 24.6 100.0 2,020 18.6 100.0

4. GPTDC, R-9 Dipterocarps 896 10.5 46.2 462 4.8 26.5 Non-dipt. 1,042 9.1 53.8 1,279 3.5 73.5 All species 1,938 12.7 100.0 1,741 7.3 100.0

Mean 2,155 71.6 1,965 68.2

In each study site, Taggat was found heavily stocked with dipterocarps in both plots at the initial" and tenth-year periods. While Acoje showed the least stocking of dipterocarps in the treated plots and GPTDC site had the lowest in the control plots. As mentioned earlier, the mean number of trees after ten years became statistically significant between plots of Sudecor and GPTDC , while Acoje and Taggat did not differ significantly (Appendix Table 5). That is, the dipterocarps found in plots with TSI treatments at Sudecor and GPTDC areas had higher increases in stocking density, as brought about by the preponderance of recruits (ingrowths) that graduated into the 5-cm dbh class, as compared to the untreated plots of other sites (please see Table 15).

Sudecor was heavily stocked with 2,591 trees per hectare in the treated plots and 2,020 trees in the control plots after ten years. While GPTDC had the least stocking among the study sites with 1,938 trees in plots with TSI treatments and 1,741 trees per hectare in the control plots (Table 5).

Out of the stand density, there was the abundance of non-dipterocarps in both plots of each site at establishment and tenth-year remeasurement periods, except in Taggat area where the dipterocarps predominated. Among the dipterocarps, Red lauan (Sltorea negrosensis) was the most abundant in both plots of Sudecor and Taggat sites, Mindanao White lauan (Sltorea mill dan ellsis) in GPTDC and Apitong (Dipterocarpus gralldiflorus) in Acoje concession during establishment and ten years after treatments . . 4,

10

Likewise, it was found out that the presence of ingrowths or recruits followed the order of abundance of the most important or dominant timber crops recorded in these working units. There were more non-dipterocarp saplings that graduated into the 5-cm class than the dipterocarps. Among the non-dipterocarps, the most abundant was the miscellaneous species group or those non-commercial species that could not be identified, hence, being lumped together under this species group (Table 15).

4.3 Stand Structure

The stand structure of the residual dipterocarp stands based on initial measurements and after ten years in both plots of each site included all trees 5 cm dbh

. and over considering the diameter range of 5 to 40 cm for peTs. The number of stems per hectare by diameter class and species group at the initial year in both plots is presented in Table 6.

Table 6. Stand structure (number of trees per hectare) at establishment period

DBHCLASS DIPTEROCARPS NON-DIPTEROCARPS ALL SPECIES

(CM) TAGGAT IACOJE ISUDECOR IGPTDC TAGGAT IACOJE ISUDECOR IGPTDC TAGGATIACOJE ISUDECORIGPTDC

TREATED PLOTS

10 982.7 231.9 520.1 420.3 423.2 833.6 457.6 600.8 1,405.9 1,065.5 977.7 1,021.1

20 264.9 96.6 164.6 130.4 118.5 284.9 202.1 170.9 383.4 381.5 366.7 301.3

30 71.6 33.5 70.9 45.4 42.9 122.6 90.0 51.2 114.5 156.1 160.9 96.6

40 29.9 16.8 23.4 20.4 14.3 40.8 21.9 15.2 44.2 57.6 45.3 35.6

50 15.6 7.5 9.5 8.0 4.3 13.4 6.5 5.4 19.9 20.9 16.0 13.4

60 9.0 3.7 3.8 2.6 3.7 5.4 2.7 1.7 12.7 9.1 6.5 4.3

70 ... 3.9 1.1 2.0 1.3 2.8 2.2 1.1 0.6 6.7 3.3 3.1 1.9

80 1.4 0.9 1.0 0.6 2.3 1.1 0.6 0.2 3.7 2.0 1.6 0.8

90 0.5 0.3 0.8

100 0.2 0.2 0.4

Total 1,3791 392[ 7961 6291 6121 1,3041 7831 8461 1,9911 1,6961 1,5791 1,475

CONTROL PLOTS

10 859.1 279.5 235.2 245.9 542.6 970.1 922.6

20 243.2 123.6 90.4 84 166.5 391.9 318.3

30 68.8 41.2 38.7 26.2 41.8 151.5 96.2

40 28.3 13.7 20.2 8.7 16.7 50.7 26.9

50 12.6 4.9 14.6 3.8 8.1 17.1 10.5

60 8.3 2.3 8.5 1.5 4.2 8.4 4.3

70 3.0 1.2 3.0 0.6 2.1 4.2 2.2

80 1.7 0.6 0.9 0.3 1.0 2.1 1.1

90 0.3 0.6

100 0.2 0.3

Total 1,225 467 412 371 783 1,596 1,383

Where: DBH Class 10 = midpoint for 5.0 - 14.9 cm diameter trees; DBH Class 20 = midpoint for 15.0 - 24.9 cm diameter trees; etc.

11

690.4 1,401.7 1,249.6 1,157.8 936.3

236.8 409.7 515.5 408.7 320.8

76.3 110.6 192.7 134.9 102.5

25.2 45.0 64.4 47.1 33.9

10.3 20.7 22.0 25.1 14.1

4.0 12.5 10.7 12.8 5.5

2.0 5.1 5.4 5.2 2.6

1.0 2.7 2.7 2.0 1.3

0.9

0.5

1,046 2,008 2,063 1,795 1,417

Likewise, it was found out that the presence of ingrowths or recruits followed the order of abundance of the most important or dominant timber crops recorded in these working units. There were more non-dipterocarp saplings that graduated into the 5-cm class than the dipterocarps. Among the non-dipterocarps, the most abundant was the miscellaneous species group or those non-commercial species that could not be identified, hence, being lumped together under this species group (Table 15).

4.3 Stand Structure

The stand structure of the residual dipterocarp stands based on initial measurements and after ten years in both plots of each site included all trees 5 cm dbh

. and over considering the diameter range of 5 to 40 cm for peTs. The number of stems per hectare by diameter class and species group at the initial year in both plots is presented in Table 6.

Table 6. Stand structure (number of trees per hectare) at establishment period

DBHCLASS DIPTEROCARPS NON-DIPTEROCARPS ALL SPECIES

(CM) TAGGAT IACOJE ISUDECOR IGPTDC TAGGAT1ACOJE ISUDECOR IGPTDC TAGGAT YCOJE lSUDECOR lGPTDC

TREATED PLOTS

10 982.7 231.9 520.1 420.3 423.2 833.6 457.6

20 264.9 96.6 164.6 130.4 118.5 284.9 202.1

30 71.6 33.5 70.9 45.4 42.9 122.6 90.0

40 29.9 16.8 23.4 20.4 14.3 40.8 21.9

50 15.6 7.5 9.5 8.0 4.3 13.4 6.5

60 9.0 3.7 3.8 2.6 3.7 5.4 2.7

70 ... 3.9 1.1 2.0 1.3 2.8 2.2 1.1

80 1.4 0.9 1.0 0.6 2.3 1.1 0.6

90 0.5 0.3

100 0.2 0.2

Total 1,379 392 796 629 612 1,304 783

CONTROL PLOTS

10 859.1 279.5 235.2 245.9 542.6 970.1 922.6

20 243.2 123.6 90.4 84 166.5 391.9 318.3

30 68.8 41.2 38.7 26.2 41.8 151.5 96.2

40 28.3 13.7 20.2 8.7 16.7 50.7 26.9

50 12.6 4.9 14.6 3.8 8.1 17.1 10.5

60 8.3 2.3 8.5 1.5 4.2 8.4 4.3

70 3.0 1.2 3.0 0.6 2.1 4.2 2.2

80 1.7 0.6 0.9 0.3 1.0 2.1 1.1

90 0.3 0.6

100 0.2 0.3

Total 1,225 467 412 371 783 1,596 1,383

Where: DBH Class 10 = midpoint for 5.0 - 14.9 cm diameter trees; DBH Class 20 = midpoint for 15.0 - 24.9 cm diameter trees; etc.

11

600.8 1,405.9 1,065.5 977.7 1,021.1

170.9 383.4 381.5 366.7 301.3

51.2 114.5 156.1 160.9 96.6

15.2 44.2 57.6 45.3 35.6

5.4 19.9 20.9 16.0 13.4

1.7 12.7 9.1 6.5 4.3

0.6 6.7 3.3 3.1 1.9

0.2 3.7 2.0 1.6 0.8

0.8

0.4

846 1,991 1,696 1,579 1,475

690.4 1,401.7 1,249.6 1,157.8 936.3

236.8 409.7 515.5 408.7 320.8

76.3 110.6 192.7 134.9 102.5

25.2 45.0 64.4 47.1 33.9

10.3 20.7 22.0 25.1 14.1

4.0 12.5 10.7 12.8 5.5

2.0 5.1 5.4 5.2 2.6

1.0 2.7 2.7 2.0 1.3

0.9

0.5

1,046 2,008 2,063 1,795 1,417

Results showed that the diameter distribution using 10-cm class boundaries or mid-point followed the J-shaped curve stand structure in both TSI plots during establishment. There were plenty of trees recorded in the lower diameter classes, i.e. 10-40 cm dbh, decreasing in number with increasing diameter class thereafter.

A number of small to medium-sized trees, usually called the "advance growth" or residuals are considered part of the new tree crops where the potential trees or favored stems are selected and marked during TSI operations. The structure of the stands in both plots after ten years period is likewise presented in Table 7. The distribution of the number of stems in different diameter classes did not show great change such that the structure still formed a reverse J-curve.

Table 7. Stand structure (number of stems per hectare) after ten years.

DBHCLASS

(CM) GPTDC

TREATED PLOS

10 1,004.2 295.8 849.2 608.7 425.3 1,089.6 912.2 735.4 1,429.5 1,385.4 1,761.4 1,344.1

20 204.2 83.3 245.8 183.3 125.0 333.3 250.0 203.8 329.2 416.6 495.8 387.1

30 79.1 33.3 91.7 50.0 54.2 137.5 125.0 66.7 133.3 170.8 216.7 116.7

40 33.3 24.9 20.8 33.3 20.8 54.2 41.7 20.8 54.1 79.1 62.5 54.1

50 15.6 6.6 12.5 12.5 8.3 12.5 12.5 8.3 23.9 19.1 25.0 20.8

60 11.2 4.2 4.2 4.2 3.8 8.3 8.3 4.2 15.0 12.5 12.5 8.4

70 4.2 4.2 4.2 2.6 2.0 4.2 3.5 1.6 6.2 8.4 7.7 4.2

80 2.2 1.7 2.0 1.4 1.6 2.4 2.0 1.2 3.8 4.1 4.0 2.6

90 1.4 1.6 3.0

100 1.2 1.2 2.4

Total 1,3541 454]-1,2331 8961-6411 1,6421 1,3581 1,0421 .. 1,9951 2,0961 2,5911 1,938

CONTROL PLOTS

10 787.5 350.0 366.7 301.1 542.0 1,146.1 932.4 822.4 1,239.5 1,496.1 1,299.1 1,123.5

20 129.6 75.0 95.8 100.0 166.7 416.7 333.3 283.3 296.3 491.7 429.1 383.3

30 66.7 38.1 41.7 29.2 58.3 179.2 116.7 104.2 125.0 217.3 158.4 133.4

40 29.2 16.7 28.0 16.7 16.7 62.5 37.5 37.5 45.9 79.2 65.5 54.2

50 16.7 12.5 12.5 8.3 8.3 16.7 20.8 16.7 25.0 29.2 33.3 25.0

60 4.2 8.3 8.3 4.2 4.2 8.3 8.3 8.3 8.4 16.6 16.6 12.5

70 4.2 2.0 4.2 1.4 3.8 8.3 4.2 4.2 8.0 10.3 8.4 5.6

80 3.9 1.4 2.0 1.1 2.0 4.2 2.0 2.4 5.9 5.6 4.0 3.5

90 1.6 1.6 3.2

100 1.2 1.2 2.4

Total 1,0421 5041 5621 4621. 1nl 1,8421 1,4581 1~91 1,7541 2,3461 2,0201 1,741

Where: DBH Class 10 = midpoint for 5.0 - 14.9 cm diameter trees; DBH Class 20 = midpoint for 15.0 - 24.9 cm diameter trees; etc.

Another stand parameter used to assess and visualize the forest structure is the mean total height of trees or termed as the site index values. In all study areas, the average height of five tallest trees of dipterocarp and non-dipterocarp species were obtained between TSI plots at establishment and ten years thereafter, as shown in Table.,8.

12

: •• : .' ... _",' .'. '.:~''''. -.( .. :. '"7.~K;., ~,-:,·:r~",:.·~. ";-::,.-;,, . ., .... ~.:.,:~~: .•. -., ·"0 '!-~'_ . ; _ . :~ "; •.• ". -. . .--'.".',.,' • :. ..: ... _.~' .-::' <" •• " ••• _.. • ' •• ': •• ' • .-';:.-:

Results showed that the diameter distribution using 10-cm class boundaries or mid-point followed the J-shaped curve stand structure in both TSI plots during establishment. There were plenty of trees recorded in the lower diameter classes, i.e. 10-40 cm dbh, decreasing in number with increasing diameter class thereafter.

A number of small to medium-sized trees, usually called the "advance growth" or residuals are considered part of the new tree crops where the potential trees or favored stems are selected and marked during TSI operations. The structure of the stands in both plots after ten years period is likewise presented in Table 7. The distribution of the number of stems in different diameter classes did not show great change such that the structure still formed a reverse J-curve.

Table 7. Stand structure (number of stems per hectare) after ten years.

DBHCLASS DIPTEROCARPS NON-DIPTEROCARPS ALL SPECIES

(CM) TAGGAT IACOJE ISUDECOR IGPTDC TAGGAT IACOJE ISUDECOR IGPTDC TAGGAT IACOJE ISUDECOR IGPTDC

TREATED PLOS

10 1,004.2 295.8 849.2 608.7 425.3 1,089.6 912.2

20

30

40

50

60

70

80

90

lOO

Total

CONTROL PLOTS

10

20

30

40

50

60

70

80

90

100

Total

Where:

204.2 83.3 245.8 183.3 125.0 333.3 250.0

79.1 33.3 91.7 50.0 54.2 137.5 125.0

33.3 24.9 20.8 33.3 20.8 54.2 41.7

15.6 6.6 12.5 12.5 8.3 12.5 12.5

11.2 4.2 4.2 4.2 3.8 8.3 8.3

4.2 4.2 4.2 2.6 2.0 4.2 3.5

2.2 1.7 2.0 1.4 1.6 2.4 2.0

1.4 1.6

1.2 1.2

1,354 454 1,233 896 641 1,642 1,358

787.5 350.0 366.7 301.1 542.0 1,146.1 932.4

129.6 75.0 95.8 100.0 166.7 416.7 333.3

66.7 38.1 41.7 29.2 58.3 179.2 116.7

29.2 16.7 28.0 16.7 16.7 62.5 37.5

16.7 12.5 12.5 8.3 8.3 16.7 20.8

4.2 8.3 8.3 4.2 4.2 8.3 8.3

4.2 2.0 4.2 1.4 3.8 8.3 4.2

3.9 1.4 2.0 1.1 2.0 4.2 2.0

1.6 1.6

1.2 1.2

1,042 504 562 462 712 1,842 1,458

DBH Class 10 = midpoint for 5.0 - 14.9 cm diameter trees; DBH Class 20 = midpoint for 15.0 - 24.9 cm diameter trees; etc.

735.4 1,429.5 1,385.4 1,761.4 1,344.1

203.8 329.2 416.6 495.8 387.1

66.7 133.3 170.8 216.7 116.7

20.8 54.1 79.1 62.5 54.1

8.3 23.9 19.1 25.0 20.8

4.2 15.0 12.5 12.5 8.4

1.6 6.2 8.4 7.7 4.2

1.2 3.8 4.1 4.0 2.6

3.0

2.4

1,042 1,995 2,096 2,591 1,938

822.4 1,239.5 1,496.1 1,299.1 1,123.5

283.3 296.3 491.7 429.1 383.3

104.2 125.0 217.3 158.4 133.4

37.5 45.9 79.2 65.5 54.2

16.7 25.0 29.2 33.3 25.0

8.3 8.4 16.6 16.6 12.5

4.2 8.0 10.3 8.4 5.6

2.4 5.9 5.6 4.0 3.5

3.2

2.4

1,279 1,754 2,346 2,020 1,741

Another stand parameter used to assess and visualize the forest structure is the mean total height of trees or termed as the site index values. In all study areas, the average height of five tallest trees of dipterocarp and non-dipterocarp species were obtained between TSI plots at establishment and ten years thereafter, as shown in Table.,8.

12

Table 8. Mean total heights of trees at establishment and after ten years.

SITE/PLOT TREATED PLOTS CONTROL PLOTS Dipt. Non-Dipt. Dipt. Non-Dipt.

A. At establishment Taggat 21.80 11.62 20.28 13.72 Acoje 17.35 12.93 17.13 16.05 Sudecor 18.05 16.97 19.52 23.88 GPTDC 15.68 14.95 15.15 18.23

Mean 18.22 14.12 18.02 17.97

B. After ten years Taggat 25.53 12.62 22.58 14.98 Acoje 20.05 15.46 19.51 18.33 Sudecor 26.50 21.87 23.44 28.14 GPTDC 20.10 18.47 19.70 21.88

Mean 23.04 17.11 21.31 20.83

Results presented in Table 8 showed that mean total heights of non­dipterocarps were higher in the control plots while the dipterocarps dominated in the treated plots during establishment phase and after ten years. Although the difference in mean total heights did not differ significantly among locations and between TSI plots (Appendix Tables 7 and 8), it was disclosed that percentage increases in mean total heights were greater in the treated plots than in the control plots among sites.

There were 26% increase, i.e. 18.22 to 23.04 meters, in mean total heights of dipterocarps and 21 % increase (from 14.12 to 17.11 m) for non-dipterocarps found in plots-with TSI treatments, as compared to 18% and 16% increases for dipterocarps and non-dipterocarps, respectively, in the control plots. These findings indicate the favorable outcome of removing a number of competitors usually belonging to miscellaneous species group in enhancing the height growth of favored and selected trees within the forest stands.

To further assess and understand the stand structure and the effects of TSI on growth responses of trees, a number of favored or most promising trees of valuable species were selected as peTs in both plots of the four working units. Table 9 presents the number of peTs per hectare at the establishment period and ten years thereafter, and showed that the stocking levels of favored trees in both plots had decreased considerably over time. It was found out that most peTs succumbed to natural death during the period covered in this study.

It is, therefore, suggested that selection and marking of additional peTs be undertaken during the second TSI treatments. The consequent effects of TSI treatments on these peTs by eliminating competition for light and growing space with other trees of lesser value, would indicate how much of the potential increment of the site are diverted or concentrated on the- selected and favored tree species.

13

Table 8. Mean total heights of trees at establishment and after ten years.

SITE/PLOT TREATED PLOTS CONTROL PLOTS Dipt. Non-Dipt. Dipt. Non-Dipt.

A. At establishment Taggat 21.80 11.62 20.28 13.72 Acoje 17.35 12.93 17.13 16.05 Sudecor 18.05 16.97 19.52 23.88 GPTDC 15.68 14.95 15.15 18.23

Mean 18.22 14.12 18.02 17.97

B. After ten years Taggat 25.53 12.62 22.58 14.98 Acoje 20.05 15.46 19.51 18.33 Sudecor 26.50 21.87 23.44 28.14 GPTDC 20.10 18.47 19.70 21.88

Mean 23.04 17.11 21.31 20.83

Results presented in Table 8 showed that mean total heights of non­dipterocarps were higher in the control plots while the dipterocarps dominated in the treated plots during establishment phase and after ten years. Although the difference in mean total heights did not differ significantly among locations and between TSI plots (Appendix Tables 7 and 8), it was disclosed that percentage increases in mean total heights were greater in the treated plots than in the control plots among sites.

There were 26% increase, i.e. 18.22 to 23.04 meters, in mean total heights of dipterocarps and 21 % increase (from 14.12 to 17.11 m) for non-dipterocarps found in plots-with TSI treatments, as compared to 18% and 16% increases for dipterocarps and non-dipterocarps, respectively, in the control plots. These findings indicate the favorable outcome of removing a number of competitors usually belonging to miscellaneous species group in enhancing the height growth of favored and selected trees within the forest stands.

To further assess and understand the stand structure and the effects of TSI on growth responses of trees, a number of favored or most promising trees of valuable species were selected as peTs in both plots of the four working units. Table 9 presents the number of peTs per hectare at the establishment period and ten years thereafter, and showed that the stocking levels of favored trees in both plots had decreased considerably over time. It was found out that most peTs succumbed to natural death during the period covered in this study.

It is, therefore, suggested that selection and marking of additional peTs be undertaken during the second TSI treatments. The consequent effects of TSI treatments on these peTs by eliminating competition for light and growing space with other trees of lesser value, would indicate how much of the potential increment of the site are diverted or concentrated on the- selected and favored tree species.

13

Table 9. Number of Potential Crop Trees (peT's) per hectare at establishment and after ten years.

SPECIES TREATED PLOTS CONTROL PLOTS

GROUP TAG GAT ACOJE SUDECOR GPTDC TAGGAT ACOJE SUDECOR GPTDC

At establishment

PCT 158 158 179 179 150 137 162 133

Other Dipterocarp 1,220 234 617 450 1,075 330 250 238

Non-Dipterocarp 612 1,304 783 846 783 1,596 1,383 1,406

All Species 1,991 1,696 1,579 1,475 2,008 2,063 1,795 1,417

After ten years

PCT 154 158 178 150 150 133 141 133

Other Dipterocarp 1,200 296 1,055 746 892 371 421 329

Non-Dipterocarp 641 1,642 1,358 1,042 712 1,842 1,458 1,279

All Species 1,995 2,096 2,591 1,938 1,754 2,346 2,020 1,741

4.4 Basal Area

The average basal area per hectare between TSI plots in each and among sites at establishment and ten years after treatments is summarized in Table 10. Results showed that the treated plots among locations had higher mean basal area production than the untreated plots. There were 14.81 sq. m per hectare basal area increase, i.e. 23.73 to 38.54 sq.m, or 62% increase in the treated plots and 7.22 sq. m per hectare (29.96 to 37;18 sq. m) or 24% increase in the control plots of all study sites in ten

. years period. Analysis of variance, however, showed no significant difference between plots at the initial and tenth-year remeasurement periods (Appendix Table 11).

Table 10. Average basal area (sq. m) per hectare at establishment period and after ten years.

SPECIES

GROUP MEAN

A. At establishment

peT 4.30 1.48 1.94 2.36 2.52 3.71 0.90 1.21 1.59 1.85

Other Dipt. 19.96 9.85 7.40 8.52 11.43 22.62 12.48 6.86 4.58 11.63

Non-Dipt. 7.36 9.83 11.47 10.47 9.78 9.20 15.59 24.92 16.20 16.48

All Species 31.62 21.16 20.81 21.35 23.73 35.53 28.97 32.99 22.37 29.96

B. After ten years

PCT 6.67 3.33 7.92· 5.83 5.94 4.58 1.67 2.50 3.54 3.07

Other Dipt. 24.17 11.67 19.17 12.92 16.98 20.00 14.58 11.67 5.63 12.97

Non-Dipt. 9.58 16.25 21.67 15.00 15.62 7.50 21.67 32.08 23.33 21.14

All Species 40.42 31.25 48.76 33.75 38.54 32.08 37.92 46.25 32.50 37.18

The higher basal area increase in the treated plots can be ascribed to the removal of inferior quality trees during TSI treatments that consequently provided

14

• '~-:. _ ; .• ~.: .. ,_ •. _~~.:: .:.-~.~'~"; '-.!~' ~'''':-' = ':.~. '.: ~:. \_.~ ,;, .... ~-..... :~ ~ .. , ....... '. -.. ',.' , '~ ...... : .... ~-'. ,-_,~~~,,":,- A7'.;; ...... '. ,"-. ':. •• ~.' ,- •• : .';7 •• " .- "~ •• ::;-.: •••• ~ ... ' • : ; .".-: '. ' •. -.: ; ~ •. ~ :-~ '.'''':~-'.",~-;- • ':-"" .:~ -.:--"·7:·.·;'~7:

Table 9. Number of Potential Crop Trees (peT's) per hectare at establishment and after ten years.

SPECIES TREATED PLOTS CONTROL PLOTS

GROUP TAG GAT ACOJE SUDECOR GPTDC TAGGAT ACOJE SUDECOR GPTDC

At establishment

PCT 158 158 179 179 150 137 162 133

Other Dipterocarp 1,220 234 617 450 1,075 330 250 238

Non-Dipterocarp 612 1,304 783 846 783 1,596 1,383 1,406

All Species 1,991 1,696 1,579 1,475 2,008 2,063 1,795 1,417

After ten years

PCT 154 158 178 150 150 133 141 133

Other Dipterocarp 1,200 296 1,055 746 892 371 421 329

Non-Dipterocarp 641 1,642 1,358 1,042 712 1,842 1,458 1,279

All Species 1,995 2,096 2,591 1,938 1,754 2,346 2,020 1,741

4.4 Basal Area

The average basal area per hectare between TSI plots in each and among sites at establishment and ten years after treatments is summarized in Table 10. Results showed that the treated plots among locations had higher mean basal area production than the untreated plots. There were 14.81 sq. m per hectare basal area increase, i.e. 23.73 to 38.54 sq.m, or 62% increase in the treated plots and 7.22 sq. m per hectare (29.96 to 37;18 sq. m) or 24% increase in the control plots of all study sites in ten

.. years period. Analysis of variance, however, showed no significant difference between plots at the initial and tenth-year remeasurement periods (Appendix Table 11).

Table 10. Average basal area (sq. m) per hectare at establishment period and after ten years.

SPECIES TREATED PLOTS CONTROL PLOTS

GROUP TAGGAT IACOJE ISUDECORIGPTDCI MEAN TAGGAT I ACOJE ISUDECOR I GPTDC I MEAN

A. At establishment

PCT 4.30 1.48 1.94 2.36 2.52 3.71 0.90 1.21 1.59 1.85

Other Dipt. 19.96 9.85 7.40 8.52 11.43 22.62 12.48 6.86 4.58 11.63

Non-Dipt. 7.36 9.83 11.47 10.47 9.78 9.20 15.59 24.92 16.20 16.48

All Species 31.62 21.16 20.81 21.35 23.73 35.53 28.97 32.99 22.37 29.96

B. After ten years

PCT 6.67 3.33 7.92· 5.83 5.94 4.58 1.67 2.50 3.54 3.07 --

Other Dipt. 24.17 11.67 19.17 12.92 16.98 20.00 14.58 11.67 5.63 12.97

Non-Dipt. 9.58 16.25 21.67 15.00 15.62 7.50 21.67 32.08 23.33 21.14

All Species 40.42 31.25 48.76 33.75 38.54 32.08 37.92 46.25 32.50 37.18

The higher basal area increase in the treated plots can be ascribed to the removal of inferior quality trees during TSI treatments that consequently provided

14

ample growing space and favorable site factors to selected or favored trees and ingrowths as compared to initially high stocking density in the control plots among sites. It was shown from previous studies that forest stands with 36 - 46 sq. m per hectare were generally sarurated at that level, i.e. any increment was balanced over a period of years by mortality in the stands (Baur 1964). In the study areas, results show that there are enough room for improvement whereby basal area increment could build up, particularly in the treated plots starting with 23.73 sq. m per hectare.

In ten years, the difference in mean basal area of dipterocarps differed significantly between plots of Sudecor and GPTDC sites, where a substantial number of intermediate-sized trees shared a higher basal area proportion in the treated plots (Appendix Table 10). The total basal area increase in plots with TSI treatments was highest in Sudecor with 27.95 sq. m per hectare, or 134% increase, followed by GPTDC with 12.4 (58%), Acoje with 10.09 (48%) and Taggat had only 8.8 (28%). The treated plots of Sudecor and GPTDC had greater proportion of the basal area shared by the PCTs and other dipterocarps group.

4.5 Volume

The average volume per hectare between plots and among sites at initial year and ten years after treatments is presented in Table 11. An average of 185.99 cu. m and 264; 14 cu. m per hectare comprised the treated plots at establishment and after ten years, respectively, while the untreated plots had 238.51 cu. m and 276.25 cu. m per hectare at the same period.

___ " As expected, the treated plots among locations had accummulated higher mean volum~ production than the control plots. There were 78.15 cu. m per hectare increase, or 42% production in the treated plots, and 37.74 cu. m per hectare or 16% increase in the control plots of all study areas in ten years time. Analysis of variance showed no significant difference between plots among sites at initial and tenth-year growing period (Appendix Table 12) as well as between plots in each site (Appendix Table 14).

Table 11. Average volume (cu. m) per hectare at establishment and after ten years.

SPECIES

GROUP MEAN

A. At establishment

PCT 28.46 7.67 16.83 12.42 16.34 24.41 3.83 9.25 8.04 11.38

Other Dipt. 152.50 105.50 80.25 81.50 104.94 164.92 144.04 89.29 49.96 112.05

Non-Dipt. 34.12 55.04 97.46 72.21 64.71 34.79 107.13 203.71 90.67 109.08

All Species 215.07 168.29 194.54 166.13 185.99 224.12 255.00 302.25 148.67 238.51 -------- -

B. After ten years

PCT 50.38 18.12 54.62 26.71 37.46 34.21 8.54 18.17 16.67 19.40

Other Dipt. 189.96 112.00 154.17 99.88 139.00 170.08 156.38 113.50 39.42 119.84

Non-Dipt. 35.46 82.50 140.79 91.96 87.68 32.42 130.50 246.46 138.67 137.01

All Species 275.80 212.62 "349.58 218.55 264.14 236.71 295.42 378.13 194.76 276.25

15

ample growing space and favorable site factors to selected or favored trees and ingrowths as compared to initially high stocking density in the control plots among sites. It was shown from previous studies that forest stands with 36 - 46 sq. m per hectare were generally sarurated at that level, i.e. any increment was balanced over a period of years by mortality in the stands (Baur 1964). In the study areas, results show that there are enough room for improvement whereby basal area increment could build up, particularly in the treated plots starting with 23.73 sq. m per hectare.

In ten years, the difference in mean basal area of dipterocarps differed significantly between plots of Sudecor and GPTDC sites, where a substantial number of intermediate-sized trees shared a higher basal area proportion in the treated plots (Appendix Table 10). The total basal area increase in plots with TSI treatments was highest in Sudecor with 27.95 sq. m per hectare, or 134% increase, followed by GPTDC with 12.4 (58%), Acoje with 10.09 (48%) and Taggat had only 8.8 (28%). The treated plots of Sudecor and GPTDC had greater proportion of the basal area shared by the PCTs and other dipterocarps group.

4.5 Volume

The average volume per hectare between plots and among sites at initial year and ten years after treatments is presented in Table 11. An average of 185.99 cu. m and 264; 14 cu. m per hectare comprised the treated plots at establishment and after ten years, respectively, while the untreated plots had 238.51 cu. m and 276.25 cu. m per hectare at the same period .

. .. " As expected, the treated plots among locations had accummulated higher mean volum~ production than the control plots. There were 78.15 cu. m per hectare increase, or 42% production in the treated plots, and 37.74 cu. m per hectare or 16% increase in the control plots of all study areas in ten years time. Analysis of variance showed no significant difference between plots among sites at initial and tenth-year growing period (Appendix Table 12) as well as between plots in each site (Appendix Table 14).

Table 11. Average volume (cu. m) per hectare at establishment and after ten years.

SPECIES TREATED PLOTS CONTROL PLOTS

GROUP T AGGAT I ACOJE I SUDECOR I GPTDC I MEAN T AGGAT I ACOJE I SUDECOR I GPTDC I MEAN

A. At establishment

PCT 28.46 7.67 16.83 12.42 16.34 24.41 3.83 9.25 8.04 11.38

Other Dipt. 152.50 105.50 80.25 81.50 104.94 164.92 144.04 89.29 49.96 112.05

Non-Dipt. 34.12 55.04 97.46 72.21 64.71 34.79 107.13 203.71 90.67 109.08

All Species 215.07 168.29 194.54 166.13 185.99 224.12 255.00 302.25 148.67 238.51

B. After ten years

PCT 50.38 18.12 54.62 26.71 37.46 34.21 8.54 18.17 16.67 19.40

Other Dipt. 189.96 112.00 154.17 99.88 139.00 170.08 156.38 113.50 39.42 119.84

Non-Dipt. 35.46 82.50 140.79 91.96 87.68 32.42 130.50 246.46 138.67 137.01

All Species 275.80 212.62 "349.58 218.55 264.14 236.71 295.42 378.13 194.76 276.25

15

The higher volume production in the treated plots indicated the favorable responses of trees to available growing space and site factors through the removal of unwanted or undesirable trees. In plots without TSI treatments, the high stocking density of intermediate or small-sized trees shared less to the volume increases among locations.

In each study site, Sudecor had the highest total volume increase in the treated plots with 155.04 cu. m per hectare, or 80% increase, followed by GPTDC with 52.42 (32%), Taggat with 60.73 (28%) and Acoje had 44.33 (26%). In the control plots, GPTDC and Sudecor also had the highest volume increase while Acoje and Taggat had the least in ten years period. This situation can further be related to the different

. secondary successional stages of the stand at the time of TSI plot establishment, i.e. Sudecor is 13-year old residual stand, GPTDC is 14-year old, Taggat is 17-year and Acoje is 22-year old forest stand. Under such prevailing conditions with different types of plant communities in the study areas the younger stands are found ideal for TSI purposes by comparing growth responses at varying stand ages, vegetational zones and climatic types.

In the study areas, Sudecor and GPTDC had higher initial stocking composed largely of medium-sized (10-40 cm dbh) trees which were mostly removed in TSI treatments. Consequently, the removal triggered off a high response in terms of volume increase of the remaining trees after being liberated from overwood. On the other hand, Acoje and Taggat sites contained a number of big-sized (40-70 cm dbh) trees that were reaching their decelerating growth rate or senility. The removal of intermediate-sized trees did not compensate for the increased growth of the remaining trees due to abundance of overtopping large-sized trees. Whitmore (1975) reported that removal of competition confined within 5-30 cm dbh classes in younger forest stands produced an accelerated growth of selected trees than bigger-sized stems in the same forest stands.

4.6 Growth Increment

Favorable biological effects of TSI are clearly manifested in the treated plots among sites, as shown in the growth responses of trees through their periodic annual diameter increment (PAl), basal area and volume increments, which are consistently higher than the untreated plots. Comparing the diameter development in the treated and control plots, it became evident that young dipterocarp stands responded very well to TSI treatments. On the average, the PCTs had a mean annual dbh increment of 0.95 cm in the treated plots as against 0.56 cm, or 69% higher than those found in the control plots of all sites (Table 12). .

Weidelt and Banaag (1982) found an average diameter increment of 1.36 cm for PCTs, or 56.3% higher in the treated plots as to compared to 0.87 cm in the control plots located in Eastern Mindanao. In this present study, the younger stands of Sudecor had the highest increment of 1.41 cm per year, while the older forest stands of Acoje had the lowest at 0.63 cm annually in the treated plots. The same diameter growth resp9~ses were exhibited in the untreated plots of the study sites. These findings show

16

. :-, .. - ~.;.~ ;'.:: : . : '. -, '; '. ' .. " " ' . .' -. '. -~ .: .. .. -;- ":.-'.'~-"': ", . I •• ~ ' •• :.' .' •

The higher volume production in the treated plots indicated the favorable responses of trees to available growing space and site factors through the removal of unwanted or undesirable trees. In plots without TSI treatments, the high stocking density of intermediate or small-sized trees shared less to the volume increases among locations.

In each study site, Sudecor had the highest total volume increase in the treated plots with 155.04 cu. m per hectare, or 80% increase, followed by GPTDC with 52.42 (32%), Taggat with 60.73 (28%) and Acoje had 44.33 (26%). In the control plots, GPTDC and Sudecor also had the highest volume increase while Acoje and Taggat had the least in ten years period. This situation can further be related to the different

.. secondary successional stages of the stand at the time of TSI plot establishment, i.e. Sudecor is 13-year old residual stand, GPTDC is 14-year old, Taggat is 17-year and Acoje is 22-year old forest stand. Under such prevailing conditions with different types of plant communities in the study areas the younger stands are found ideal for TSI purposes by comparing growth responses at varying stand ages, vegetational zones and climatic types.

In the study areas, Sudecor and GPTDC had higher initial stocking composed largely of medium-sized (10-40 cm dbh) trees which were mostly removed in TSI treatments. Consequently, the removal triggered off a high response in terms of volume increase of the remaining trees after being liberated from overwood. On the other hand, Acoje and Taggat sites contained a number of big-sized (40-70 cm dbh) trees that were reaching their decelerating growth rate or senility. The removal of intermediate-sized trees did not compensate for the increased growth of the remaining trees due to abundance of overtopping large-sized trees. Whitmore (1975) reported that removal of competition confined within 5-30 cm dbh classes in younger forest stands produced an accelerated growth of selected trees than bigger-sized stems in the same forest stands.

4.6 Growth Increment

Favorable biological effects of TSI are clearly manifested in the treated plots among sites, as shown in the growth responses of trees through their periodic annual diameter increment (PAl), basal area and volume increments, which are consistently higher than the untreated plots. Comparing the diameter development in the treated and control plots, it became evident that young dipterocarp stands responded very well to TSI treatments. On the average, the PCTs had a mean annual dbh increment of 0.95 cm in the treated plots as against 0.56 cm, or 69% higher than those found in the control plots of all sites (Table 12). .

Weidelt and Banaag (1982) found an average diameter increment of 1.36 cm for PCTs, or 56.3% higher in the treated plots as to compared to 0.87 cm in the control plots located in Eastern Mindanao. In this present study, the younger stands of Sudecor had the highest increment of 1.41 cm per year, while the older forest stands of Acoje had the lowest at 0.63 cm annually in the treated plots. The same diameter growth resp9~ses were exhibited in the untreated plots of the study sites. These findings show

16

. . .. -. '. -~ .: ... ' •.•• 7 •• - •• - •••••• " • , ... '-. ',' ,.' _,'4 I.· ••••• :.· ••••••• -;.: •• ~.~ ••••

that the trees found in Mindanao have faster diameter growth than those found in Luzon, whether in the treated or· control plots. These results further imply that the cutting cycle can be shortened considerably due to faster growth rates of trees under TSI treatments. .

Table 12. Annual Diameter Increment (cm) of PCTs.

TSI TREATED CONTROL SITES PLOTS PLOTS

Sudecor (13-year old) 1.41 0.70 GPTDC (14-year old) 0.81 0.62 Taggat (17-year old) 0.95 0.51 Acoje (22-year old) 0.63 0.39

Mean 0.95 0.56

In all four series of TSI sites, there had been higher total basal and volume production in the treated than in the control plots (Tables 10 and 11). From these production figures, the average annual basal area increment of each and among sites and tree species groupings between plots have been derived and is presented in Table 13. Results showed that the annual basal area increase for all species in the treated plots ranged from 0.880 to 2.795 sq. m per hectare and in the control plots from -0.345 to 1.326 sq. m per hectare. There had been a higher total basal area increment in the treated plots (1.481 sq. m per hectare) than in plots without TSI treatments (0.722 sq. m per hectare). Analysis of variance showed significant difference between plots of Sudecor, while the rest did not differ significantly (Appendix Table 15).

Table 13. Average Annual Basal Area Increment (sq. m per hectare)

SPECIES TAG GAT ACOJE SUDECOR GPTDC MEAN

GROUPINGS B. A. % Inc. B. A. % Inc. B. A. % Inc. B. A. % Inc.

A. Treated Plots PCT 0.237 5.5 0.185 12.5 0.598 30.8 0.347 14.7 0.342

Other Dipt. 0.421 2.1 0.182 1.8 1.177 15.9 0.440 5.2 0.555 Non-dipt. 0.222 3.0 0.642 6.5 1.020 8.9 0.453 4.3 0.584

All Species 0.880 2.9 1.009 4.8 2.795 13.4 1.240 5.8 1.481

B. Control Plots PCT 0.087 2.3 0.077 8.6 0.129 10.7 0.195 12.3 0.122

Other Dipt. -0.262 -1.2 0.210 1.7 0.481 7.0 0.105 2.3 0.133 Non-dipt. -0.170 -1.8 0.608 3.9 0.716 2.9 0.713 4.4 0.467

All Species -0.345 -0.9 0.895 3.1 1.326 4.0 1.013 4.5 0.722 --- -

Note: The negative values indicate the death of 60-cm diameter tree and other non-dipterocarps in the vicinities during the tenth-year remeasurement.

The highest basal area increment in plots with TSI treatments was found in Sudecor while the least was in Taggat area. There was 13.4% increase after ten years in the treated plots of Sudecor; with the peTs showing the highest relative basal area increment per year in all the plots of the study areas. Taggat had only 2.9% increase

17

that the trees found in Mindanao have faster diameter growth than those found in Luzon, whether in the treated or· control plots. These results further imply that the cutting cycle can be shortened considerably due to faster growth rates of trees under TSI treatments. .

Table 12. Annual Diameter Increment (cm) of PCTs.

TSI TREATED CONTROL SITES PLOTS PLOTS

Sudecor (13-year old) 1.41 0.70 GPTDC (14-year old) 0.81 0.62 Taggat (17-year old) 0.95 0.51 Acoje (22-year old) 0.63 0.39

Mean 0.95 0.56

In all four series of TSI sites, there had been higher total basal and volume production in the treated than in the control plots (Tables 10 and 11). From these production figures, the average annual basal area increment of each and among sites and tree species groupings between plots have been derived and is presented in Table 13. Results showed that the annual basal area increase for all species in the treated plots ranged from 0.880 to 2.795 sq. m per hectare and in the control plots from -0.345 to 1.326 sq. m per hectare. There had been a higher total basal area increment in the treated plots (1.481 sq. m per hectare) than in plots without TSI treatments (0.722 sq. m per hectare). Analysis of variance showed significant difference between plots of Sudecor, while the rest did not differ significantly (Appendix Table 15).

Table 13. Average Annual Basal Area Increment (sq. m per hectare)

SPECIES TAG GAT ACOJE SUDECOR GPTDC MEAN

GROUPINGS B. A. % Inc. B. A. % Inc. B. A. % Inc. B. A. % Inc.

A. Treated Plots PCT 0.237 5.5 0.185 12.5 0.598 30.8 0.347 14.7 0.342

Other Dipt. 0.421 2.1 0.182 1.8 1.177 15.9 0.440 5.2 0.555 Non-dipt. 0.222 3.0 0.642 6.5 1.020 8.9 0.453 4.3 0.584

All Species 0.880 2.9 1.009 4.8 2.795 13.4 1.240 5.8 1.481

B. Control Plots PCT 0.087 2.3 0.077 8.6 0.129 10.7 0.195 12.3 0.122

Other Dipt. -0.262 -1.2 0.210 1.7 0.481 7.0 0.105 2.3 0.133 Non-dipt. -0.170 -1.8 0.608 3.9 0.716 2.9 0.713 4.4 0.467

All Species -0.345 -0.9 0.895 3.1 1.326 4.0 1.013 4.5 0.722

Note: The negatIve values mdIcate the death of 60-cm dIameter tree and other non-dipterocarps in the vicinities during the tenth-year remeasurement.

The highest basal area increment in plots with TSI treatments was found in Sudecor while the least was in Taggat area. There was 13.4% increase after ten years in the treated plots of Sudecor; with the peTs showing the highest relative basal area increment per year in all the plots of the study areas. Taggat had only 2.9% increase

17

due to the natural death (mortality) of bigger-sized non-dipterocarps during the tenth­remeasurement period, particularly in the control plots (Table 13).

On the other hand, the average annual volume increment of each and among TSI sites and species groupings between plots is summarized in Table 14. In all the study areas, the treated plots had higher total volume increment (7.81 cu. m per hectare) than in the control plots (4.37 cu. m per hectare). The total mean annual increment was higher in the treated plots of each site and reached up to 15.50 cu. m in Sudecor, 6.07 cu. m in Taggat, 5.24 cu. m in GPTDC and 4.43 cu. m in Acoje. Analysis of variance, however, showed no significant difference between plots of all working units (Appendix Table 16).

Of the tree species groupings, the PCTs shared the highest basal area and volume increments annually, particularly in plots with TSI treatments. These findings showed that the potential increment of the site can be directed or concentrated on selected and favored trees while the share of less valuable tree species is concomitanttly reduced.

Table 14. Average Annual Volume Increment (cu. m per hectare)

SPECIES TAG GAT ACOJE SUDECOR GPTDC MEAN

GROUPINGS Vol. % Inc. Vol. % Inc. Vol. % Inc. Vol. % Inc.

A. Treated Plots PCT 2.19 7.7 1.04 0.1 3.78 0.2 1.43 0.1 2.11

Other Dipt. 3.75 2.4 0.65 0.0 7.39 0.1 1.84 0.0 3.41 Non-dipt. 0.13 0.0 2.75 0.1 4.33 0.1 1.97 0.0 2.29

All Species 6.07 0.0 4.43 0.0 15.50 0.1 5.24 0.0 7.81

B. Control Plots PCT 0.98 0.0 0.47 0.1 0.89 0.1 0.86 0.1 0.80

Other Dipt. 0.52 0.0 1.23 0.0 2.42 0.0 -1.05 0.0 0.78 Non-dipt. -0.24 0.0 2.34 0.0 4.28 0.0 4.80 0.1 2.79

All Species 1.26 0.0 4.04 0.0 7.59 0.0 4.61 0.0 4.37

Note: The negative values indicate the death of big-sized trees in the plots.

4.7 Tree Mortality and Ingrowth

The average annual mortality of trees per hectare within the ten-year period between plots of all sites is summarized in Table 15. A higher number of dead trees were counted in the control plots (38 trees per hectare) as compared to the treated plots, with 27 stems per hectare. Analysis of -variance of the mean number of dead trees was significant between plots of GPTDC, Sudecor, Taggat and Acoje sites (Appendix Table 17). There were more dead trees belonging to the non-dipterocarp species group in the control plots of these study areas.

GPTDC had the highest annual loss with 55 trees per hectare, Sudecor with 46 trees,_.t,\coje with 35 trees and Taggat with 17 trees per hectare in the control plots. The

18

. ~-.~., .. ~ ; -; .. -' .. ' ... ". . . .... ' ...... ~'" .... ~: " . ':.' '," .,'.: '~'--;' .. '.'.'.'.~... , .... : .:.::'~'''' .. '-'~-:''-~'~';''''~~' .. :.~' .. -:.:: ... ....-'~.:'''~

due to the natural death (mortality) of bigger-sized non-dipterocarps during the tenth­remeasurement period, particularly in the control plots (Table 13).

On the other hand, the average annual volume increment of each and among TSI sites and species groupings between plots is summarized in Table 14. In all the study areas, the treated plots had higher total volume increment (7.81 cu. m per hectare) than in the control plots (4.37 cu. m per hectare). The total mean annual increment was higher in the treated plots of each site and reached up to 15.50 cu. m in Sudecor, 6.07 cu. m in Taggat, 5.24 cu. m in GPTDC and 4.43 cu. m in Acoje. Analysis of variance, however, showed no significant difference between plots of all working units (Appendix Table 16).

Of the tree species groupings, the PCTs shared the highest basal area and volume increments annually, particularly in plots with TSI treatments. These findings showed that the potential increment of the site can be directed or concentrated on selected and favored trees while the share of less valuable tree species is concomitanttly reduced.

Table 14. Average Annual Volume Increment (cu. m per hectare)

SPECIES TAG GAT ACOJE SUDECOR GPTDC MEAN

GROUPINGS Vol. % Inc. Vol. % Inc. Vol. % Inc. Vol. % Inc.

A. Treated Plots PCT 2.19 7.7 1.04 0.1 3.78 0.2 1.43 0.1 2.11

Other Dipt. 3.75 2.4 0.65 0.0 7.39 0.1 1.84 0.0 3.41 Non-dipt. 0.13 0.0 2.75 0.1 4.33 0.1 1.97 0.0 2.29

All Species 6.07 0.0 4.43 0.0 15.50 0.1 5.24 0.0 7.81

B. Control Plots PCT 0.98 0.0 0.47 0.1 0.89 0.1 0.86 0.1 0.80

Other Dipt. 0.52 0.0 1.23 0.0 2.42 0.0 -1.05 0.0 0.78 Non-dipt. -0.24 0.0 2.34 0.0 4.28 0.0 4.80 0.1 2.79

All Species 1.26 0.0 4.04 0.0 7.59 0.0 4.61 0.0 4.37

Note: The negatIve values mdIcate the death of bIg-sIzed trees m the plots.

4.7 Tree Mortality and Ingrowth

The average annual mortality of trees per hectare within the ten-year period between plots of all sites is summarized in Table 15. A higher number of dead trees were counted in the control plots (38 trees per hectare) as compared to the treated plots, with 27 stems per hectare. Analysis of -variance of the mean number of dead trees was significant between plots of GPTDC, Sudecor, Taggat and Acoje sites (Appendix Table 17). There were more dead trees belonging to the non-dipterocarp species group in the control plots of these study areas.

GPTDC had the highest annual loss with 55 trees per hectare, Sudecor with 46 trees,_.t,\coje with 35 trees and Taggat with 17 trees per hectare in the control plots. The

18

.... - .. '"., ,", .. -.- ...... ", .............. ',' .' .". ~. '. ' .' .... . " . '.-.. ,' .... ' .'. . .... -;' ,- .. " .~., :." .' ": ... ', '-, .. -;:", ';' ....... " -:- : ... ...-. :'",

slightly higher mortality in the untreated plots was due to denser stocking or adverse . competition between trees (Table 5). In plots with TSI treatments, Taggat had the highest annual loss with 44 stems per hectare while Acoje had the least with 8 dead trees per hectare. .

Table 15. Average Annual Mortality and Ingrowth (Number of stems/hectare).

TSI DIPTEROCARPS NON-DIPTEROCARPS ALL SPECIES SITES Mortality Ingrowth Mortality Ingrowth Mortality Ingrowth

A. Treated Plots Taggat 28 4 16 12 44 16 Acoje 8 7 46 8 54 Sudecor 10 47 11 82 21 129 GPTDC 7 23 27 28 34 51

Mean 12 20 15 42 27 62

B. Control Plots Taggat 11 8 6 12 17 20 Acoje 5 4 30 33 35 37 Sudecor 11 26 35 57 46 83 GPTDC 14 12 41 24 55 36

Mean 10 12 28 32 38 44

The non-dipterocarp tree species showed a much higher annual loss among sites since this group was composed largely of pioneers that were gradually overgrown by other tree species in the secondary successional stages. In fact, most of the dead trees were found in the lower diameter classes (10-20 cm) in both plots of each site, particularly in Taggat and Acoje areas (Tables 6 and 7). The overtopping dense canopies of dominants and co-dominants had screened and created unfavorable light conditions near the forest floor. Abdul Rahman, et.a!. (1991) reported a mean mortality rate of 2% for all trees in ten years period, with non-dipterocarps having an actual mortality of about ten times greater than the dipterocarps in Tekam Forest Reserve, Peninsular Malaysia.

On the other hand, the average annual ingrowth or recruits per hectare was higher in plots with TSI treatments than the control plots among locations (Table 15). A higher number of ingrowths were recorded in the treated plots (62 recruits per hectare) as compared to the control plots, with 44 ingrowths per hectare. Comparison of the difference in number of recruits per hectare was significant between plots of Sudecor and GPTDC, while the ingrowth rate in Taggat and Acoje was not significant between plots in ten years period (Appendix Table 18).

Understandably, the more open crown canopies in treated plots of younger stands of Sudecor and GPTDC has encouraged invasion of pioneers in gaps or additional space due to favorable site factors. Most of the recruits that graduated into the 5::~m dbh class in ten years period belonged to the non-dipterocarp tree species.

19

slightly higher mortality in the untreated plots was due to denser stocking or adverse . competition between trees (Table 5). In plots with TSI treatments, Taggat had the highest annual loss with 44 stems per hectare while Acoje had the least with 8 dead trees per hectare. .

Table 15. Average Annual Mortality and Ingrowth (Number of stems/hectare).

TSI DIPTEROCARPS NON-DIPTEROCARPS ALL SPECIES SITES Mortality Ingrowth Mortality Ingrowth Mortality Ingrowth

A. Treated Plots Taggat 28 4 16 12 44 16 Acoje 8 7 46 8 54 Sudecor 10 47 11 82 21 129 GPTDC 7 23 27 28 34 51

Mean 12 20 15 42 27 62

B. Control Plots Taggat 11 8 6 12 17 20 Acoje 5 4 30 33 35 37 Sudecor 11 26 35 57 46 83 GPTDC 14 12 41 24 55 36

Mean 10 12 28 32 38 44

The non-dipterocarp tree species showed a much higher annual loss among sites since this group was composed largely of pioneers that were gradually overgrown by other tree species in the secondary successional stages. In fact, most of the dead trees were found in the lower diameter classes (10-20 cm) in both plots of each site, particularly in Taggat and Acoje areas (Tables 6 and 7). The overtopping dense canopies of dominants and co-dominants had screened and created unfavorable light conditions near the forest floor. Abdul Rahman, et.a!. (1991) reported a mean mortality rate of 2% for all trees in ten years period, with non-dipterocarps having an actual mortality of about ten times greater than the dipterocarps in Tekam Forest Reserve, Peninsular Malaysia.

On the other hand, the average annual ingrowth or recruits per hectare was higher in plots with TSI treatments than the control plots among locations (Table 15). A higher number of ingrowths were recorded in the treated plots (62 recruits per hectare) as compared to the control plots, with 44 ingrowths per hectare. Comparison of the difference in number of recruits per hectare was significant between plots of Sudecor and GPTDC, while the ingrowth rate in Taggat and Acoje was not SIgnificant between plots in ten years period (Appendix Table 18).

Understandably, the more open crown canopies in treated plots of younger stands of Sudecor and GPTDC has encouraged invasion of pioneers in gaps or additional space due to favorable site factors. Most of the recruits that graduated into the 5::pm dbh class in ten years period belonged to the non-dipterocarp tree species.

19

-':'.

Yong (1990) reported a mean value of 3.3% ingrowth rate for all trees, based on recruits of 5 cm dbh and up, fourteen years after logging in Peninsular Malaysia, with the non-dipterocarps comprising most of the ingrowths.

From the above findings of this study, it is therefore very ideal to select and apply the first TSI treatments in residual dipterocarp stands of 10-15 years after logging, and another 10-15 years thereafter to undertake the second TSI treatments, to obtain immediate and favorable biological effects from this silvicultural operation.

4.8 Economic Production of the Study Areas

. Aside from the silvicultural advantages or beneficial biological effects of TSI treatments, the removals of girdled trees using appropriate timber extraction method may offer the possibility of an intermediate yield between cutting cycles. This alternative proposition of mechanically utilizing the undesirable or unwanted trees has been brought forward to promote the nationwide field implementation of TSI, considering that it requires cost outlay from timber companies and the concerned government agency when conducting TSI in cancelled or inactive concession areas. Likewise, the benefits to be derived out of TSI operations, in terms of actual additional revenue, can only be realized during the next cyclic cut, quite a long gestation period of investment. Therefore, there is a need to examine the benefits and costs of this phase of selective logging system when economic utilization of TSI removals will be allowed.

The economic analysis of TSI operations in the study areas entailed the following assumptions :

a. Two (2) TSI operations are undertaken, i.e. at the time of plot establishment and at the tenth-year period thereafter, within the entire duration of the cutting cycle.

b. The rate of interest (discount) at 18% is used in the computation for all sites.

c. A mortality rate of 25% throughout the cutting cycle (or 1 % annually) is used in stand or yield projections.

d. The average market price of TSI materials corresponds to the prevailing price offuelwood and other wood uses in the locality.

e. The costs and prices are co~stant within the analysis period.

The economic production involved the determination of the benefits received and the corresponding costs incurred in the TSI activities. The tangible benefits derived from TSI include the timber removed during treatments (see Tables 2 and 3) and the incremental harvestable yield at the end of the cutting cycle. The costs of TSI operations involved the labor. requirement, diagnostic sampling surveys, vines and bamP.?o cuttings, girdling, felling, yarding and road construction costs ..

20

.. ' , ..... ~::-~ . .,. .. ~-.. '>.~ .. ';:"\" ... -.'~.~ .• " .• -:.', :.'-, .~."- .--':'<~ ." .', ..... :., l~ •• " '".;.' ;; ':. :'" .' •• ': •••••••• :-•.• ,".':' ••• '--;.' .:

Yong (1990) reported a mean value of 3.3% ingrowth rate for all trees, based on recruits of 5 cm dbh and up, fourteen years after logging in Peninsular Malaysia, with the non-dipterocarps comprising most of the ingrowths.

From the above findings of this study, it is therefore very ideal to select and apply the first TSI treatments in residual dipterocarp stands of 10-15 years after logging, and another 10-15 years thereafter to undertake the second TSI treatments, to obtain immediate and favorable biological effects from this silvicultural operation.

4.8 Economic Production of the Study Areas

. Aside from the silvicultural advantages or beneficial biological effects of TSI treatments, the removals of girdled trees using appropriate timber extraction method may offer the possibility of an intermediate yield between cutting cycles. This alternative proposition of mechanically utilizing the undesirable or unwanted trees has been brought forward to promote the nationwide field implementation of TSI, considering that it requires cost outlay from timber companies and the concerned government agency when conducting TSI in cancelled or inactive concession areas. Likewise, the benefits to be derived out of TSI operations, in terms of actual additional revenue, can only be realized during the next cyclic cut, quite a long gestation period of investment. Therefore, there is a need to examine the benefits and costs of this phase of selective logging system when economic utilization of TSI removals will be allowed.

The economic analysis of TSI operations III the study areas entailed the following assumptions :

a. Two (2) TSI operations are undertaken, i.e. at the time of plot establishment and at the tenth-year period thereafter, within the entire duration of the cutting cycle.

b. The rate of interest (discount) at 18% is used in the computation for all sites.

c. A mortality rate of 25% throughout the cutting cycle (or 1 % annually) is used in stand or yield projections.

d. The average market price of TSI materials corresponds to the prevailing price offuelwood and other wood uses in the locality.

e. The costs and prices are co~stant within the analysis period.

The economic production involved the determination of the benefits received and the corresponding costs incurred in the TSI activities. The tangible benefits derived from TSI include the timber removed during treatments (see Tables 2 and 3) and the incremental harvestable yield at the end of the cutting cycle. The costs of TSI operations involved the labor. requirement, diagnostic sampling surveys, vines and bamP.?o cuttings, girdling, felling, yarding and road construction costs ..

20

.'-•• • •• _ ..... : •• l~ ••• _ ... ; •• ;;':.: ••• :._·.~.·:·: •••••• -•• :.'.' •••••••••••• : ::.'_ .~ ••• ':.,

4.8.1 Revenue

The revenue obtained in TSI operations is calculated from the volume of wood raw materials or removals and the incremental yield at the duration of the second cutting cycle. The expected gross revenue is determined from these wood volumes and the stumpage price of sawlogs as derived from residual dipterocarp sites and those of fuel wood and other wood products from TSI areas.

To arrive at the permissible cut, a diameter-based stand table projection was used and from which the harvestable volume was computed using the DENR Administrative Order No. 12, series of 1992 (Formulae for Annual Allowable Cut for Residual Dipterocarp Forests). The permissible (harvestable) cut for the next cutting cycle in all TSI sites is presented in Table 16. The empirical findings showed that the volume of wood harvestable at the end of the cutting cycle were higher in the treated plots of all study sites. GPTDC had 108.52 cubic meters per hectare, or 27% greater than the control plots with 85.55 cu. m per hectare; Sudecor had 224.91 cu. m per hectare, or 17% higher than the untreated plots (192.72 cu. m per hectare), Taggat had 141.16 cu. m per hectare, or 12% more than the control plots (126.37 cu. m per hectare) and Acoje had 82.91 cu. m per hectare, or 1% higher than in plots without TSI treatments (82.05 cu. m per hectare). An average of 14% increase in yield is obtained from among the TSI study sites after ten years.

Table 16. Permissible second cyclic cut (cu. m per hectare).

SITE

Taggat Acoje

Sudecor GPTDC

TREATED PLOTS

141.16 82.91

224.91 108.52

CONTROL PLOTS

126.37 82.05

192.72 85.55

In a similar study, Cruz (1982) assumed a 20% increase in yield for the treated plots of the selected timber concessions. She obtained the permissible second cyclic cuts that were almost equal, if not greater, than the first cut. In this present study, a higher permissible cut was found in the younger forest stands of Sudecor site while the least was in the older stands of Acoje concession.

4.8.2 Costs and Prices

Other economic data arid assumptions obtained through personal communications and available management records and operations plans of the four working units are summarized in Table 17. In particular, the log production costs in TSI were gathered from the Philippine-German project that undertook a preliminary harvesting trials using Koller K300 (72 Hp) with mobile skyline yarder within Sudecor concession areas (Ludwig and. Yambao, 1991). The costs of TSI labor requirement, diagp.ostic sampling surveys, vines and bamboo cuttingibrushing, girdling and other

21

4.8.1 Revenue

The revenue obtained in TSI operations is calculated from the volume of wood raw materials or removals and the incremental yield at the duration of the second cutting cycle. The expected gross revenue is determined from these wood volumes and the stumpage price of sawlogs as derived from residual dipterocarp sites and those of fuel wood and other wood products from TSI areas.

To arrive at the permissible cut, a diameter-based stand table projection was used and from which the harvestable volume was computed using the DENR Administrative Order No. 12, series of 1992 (Formulae for Annual Allowable Cut for Residual Dipterocarp Forests). The permissible (harvestable) cut for the next cutting cycle in all TSI sites is presented in Table 16. The empirical findings showed that the volume of wood harvestable at the end of the cutting cycle were higher in the treated plots of all study sites. GPTDC had 108.52 cubic meters per hectare, or 27% greater than the control plots with 85.55 cu. m per hectare; Sudecor had 224.91 cu. m per hectare, or 17% higher than the untreated plots (192.72 cu. m per hectare), Taggat had 141.16 cu. m per hectare, or 12% more than the control plots (126.37 cu. m per hectare) and Acoje had 82.91 cu. m per hectare, or 1 % higher than in plots without TSI treatments (82.05 cu. m per hectare). An average of 14% increase in yield is obtained from among the TSI study sites after ten years.

Table 16. Permissible second cyclic cut (cu. m per hectare).

SITE

Taggat Acoje

Sudecor GPTDC

TREATED PLOTS

141.16 82.91

224.91 108.52

CONTROL PLOTS

126.37 82.05

192.72 85.55

In a similar study, Cruz (1982) assumed a 20% increase in yield for the treated plots of the selected timber concessions. She obtained the permissible second cyclic cuts that were almost equal, if not greater, than the first cut. In this present study, a higher permissible cut was found in the younger forest stands of Sudecor site while the least was in the older stands of Acoje concession.

4.8.2 Costs and Prices

Other economic data arid assumptions obtained through personal communications and available management records and operations plans of the four working units are summarized in Table 17. In particular, the log production costs in TSI were gathered from the Philippine-German project that undertook a preliminary harvesting trials using Koller K300 (72 Hp) with mobile skyline yarder within Sudecor concession areas (Ludwig and. Yambao, 1991). The costs of TSI labor requirement, diagp.ostic sampling surveys, vines and bamboo cuttingibrushing, girdling and other

21

«,

maintenance activities were obtained from the DENR Memorandum Circular No. 19, series of 1989, regarding the guidelines on TSI costs per hectare. The market or selling prices of sawlogs, fuelwood, poles, logging wastes and other wood products were obtained from Reyes (1994).

Table 17. Economic data and assumptions ofTSI operations.

ITEMS TAGGAT ACOJE SUDECOR GPTDC

1 . Interest rate (%) 18 18 18 18 2. Log production

cost (Pesos/cu. m) TSI area 525.00 440.00 518.25 498.00 Residual stand 3,865.00 2,215.00 2,400.00 1,768.00

3. First TSI Treatment 3,500.00 3,500.00 3,500.00 3,500.00 (Pesos/ha, Year 0)

4. 2nd & 3rd TSI Trts 3,500.00 3,500.00 3,500.00 3,500.00 (Years 10 & 20)

5. Ave. market price of TSI materials (Pesos/cu.m) TSI area 600.00 480.00 550.00 550.00 Residual stand 4,500.00 5,294.00 3,700.00 4,500.00

6. Stumpage price (Pesos/cu. m) TSI area 75.00 40.00 31.75 52.00 Residual stand 635.00 3,079.00 1,300.00 2,732.00

7. TSI yield (cu. m per ha. at 70% recovery) First TSI Treatment 47.18 54.18 63.14 69.51 Second TSI Trts. 39.48 18.06 17.36 26.95

8. Incremental yield 98.81 58.04 157.44 75.96 (cu. m per hectare)

The average market price of wood raw materials from TSI areas correspond to that of fuel wood, industrial wood, poles, logging wastes and other available wood uses since most of the TSI removals are of low-quality wood products. While in the residual forest stands of the study areas under commercial logging operations, the wood materials or products produced were composed largely of good quality logs, hence, the average price of sawlogs derived therefrom was used in the analysis. Thus, the stumpage price or "farm gate price" was calculated from the difference between the average market or selling price of logs, fuelwood and other wood products and the log production costs plus margin for profit and risk. --

An interest (discount) rate of 18% was used in the analysis of TSI operations in each of the study area considering the prevailing rates imposed by commercial banks on loans secured by timber companies. Sensitivity analysis was done to determine the effects of varying the interest (discount) rates.

22

'.

• -. ..' ~.: .... "'+." .. ::;. "," .,:, -; -: : -' .. :,. '.-.', ~ . \, . .'.~ .. " ' .. ' ~~. -:.' .:,~.: .... :" '';'" -~ ': "',: __ :." ~ ~ .. '"', .' ~.: .•.. :. '~. ,-.: ;.~: -'~ ·~o'.I:"'-4_"~:~··· 7~·-::.~":·-:··. '~.'; :. -':" .. ' .:~.:.:-:-:-:<. :-.-~ ... ;~ '~ .

maintenance activities were obtained from the DENR Memorandum Circular No. 19, series of 1989, regarding the guidelines on TSI costs per hectare. The market or selling prices of sawlogs, fuelwood, poles, logging wastes and other wood products were obtained from Reyes (1994).

Table 17. Economic data and assumptions ofTSI operations.

ITEMS TAGGAT ACOJE SUDECOR GPTDC

1 . Interest rate (%) 18 18 18 18 2. Log production

cost (Pesos/cu. m) TSI area 525.00 440.00 518.25 498.00 Residual stand 3,865.00 2,215.00 2,400.00 1,768.00

3. First TSI Treatment 3,500.00 3,500.00 3,500.00 3,500.00 (Pesos/ha, Year 0)

4. 2nd & 3rd TSI Trts 3,500.00 3,500.00 3,500.00 3,500.00 (Years 10 & 20)

5. Ave. market price of TSI materials (Pesos/cu.m) TSI area 600.00 480.00 550.00 550.00 Residual stand 4,500.00 5,294.00 3,700.00 4,500.00

6. Stumpage price (Pesos/cu. m) TSI area 75.00 40.00 31.75 52.00 Residual stand 635.00 3,079.00 1,300.00 2,732.00

7. TSI yield (cu. m per ha. at 70% recovery) First TSI Treatment 47.18 54.18 63.14 69.51 Second TSI Trts. 39.48 18.06 17.36 26.95

8. Incremental yield 98.81 58.04 157.44 75.96 (cu. m per hectare)

The average market price of wood raw materials from TSI areas correspond to that of fuel wood, industrial wood, poles, logging wastes and other available wood uses since most of the TSI removals are of low-quality wood products. While in the residual forest stands of the study areas under commercial logging operations, the wood materials or products produced were composed largely of good quality logs, hence, the average price of sawlogs derived therefrom was used in the analysis. Thus, the stumpage price or "farm gate price" was calculated from the difference between the average market or selling price of logs, fuelwood and other wood products and the log production costs plus margin for profit and risk. --

An interest (discount) rate of 18% was used in the analysis of TSI operations in each of the study area considering the prevailing rates imposed by commercial banks on loans secured by timber companies. Sensitivity analysis was done to determine the effects of varying the interest (discount) rates.

22

'.

Moreover, the average TSI yield or timber removals was based on 70% recovery of the total volume yield of trees removed during treatments in all the study areas (Tables 2 and 3). While the incremental harvestable yield at the end of the cutting cycle was based on Table 16.

The revenue and cost statements of TSI operations in each study area are presented in Appendix Table 19.

4.8.3 Economic Criteria

The criteria used in the economic analysis of TSI operations are the Benefit/Cost Ratio (BCR) and the Present Net Worth (PNW) or equivqlent to the Net

. Present Value (NPV). Based on the economic data and assumptions gathered in each study area, the returns of TSI investment using BCR and PNW are summarized in Table 18.

Table 18. PNW and BCR values ofTSI operations.

SITES PNW (Pesos/ha) BCR

Taggat + 1,024.40 1.24 Acoje + 1,474.27 1.35

Sudecor + 2,466.51 1.59 GPTDC + 2,044.86 1.49

Results showed that all TSI study sites had positive PNW values and BCR greater than unity. Sudecor had positive PNW values of P2,466.51 per hectare, P2,044.86 per hectare in GPTDC, PI,474.27 per hectare in Acoje and Pl,024.40 per hectare in Taggat area. These positive trends and figures indicated the economically worthwhile investment of TSI operations following the same sets of conditions, data and assumptions as used in this study. In particular, the stumpage prices of the wood products in these localities were much higher than the log production costs.

In terms of BCR, all the study sites had values greater than unity, i.e. Sudecor with the highest at 1.59, GPTDC with 1.49, Acoje with 1.35 and Taggat with 1.24. A figure greater than unity further indicated the economic feasibility of TSI operations considering that the wood products out of the TSI removals from each of the stdy area were found to have economical uses and market values.

4.8.4 Sensitivity Analysis

TSI operations have been viewed by most timber companies as an expensive business venture that are subject to risk and uncertainty. In this regard, a sensitivity analysis is usually done to determine the changes in values of the economic criteria use~. with varying factors involved in the working assumptions. The factors tested

23

Moreover, the average TSI yield or timber removals was based on 70% recovery of the total volume yield of trees removed during treatments in all the study areas (Tables 2 and 3). While the incremental harvestable yield at the end of the cutting cycle was based on Table 16.

The revenue and cost statements of TSI operations in each study area are presented in Appendix Table 19.

4.8.3 Economic Criteria

The criteria used in the economic analysis of TSI operations are the Benefit/Cost Ratio (BCR) and the Present Net Worth (PNW) or equivqlent to the Net

. Present Value (NPV). Based on the economic data and assumptions gathered in each study area, the returns of TSI investment using BCR and PNW are summarized in Table 18.

Table 18. PNW and BCR values ofTSI operations.

SITES PNW (Pesos/ha) BCR

Taggat + 1,024.40 1.24 Acoje + 1,474.27 1.35

Sudecor + 2,466.51 1.59 GPTDC + 2,044.86 1.49

Results showed that all TSI study sites had positive PNW values and BCR greater than unity. Sudecor had positive PNW values of P2,466.51 per hectare, P2,044.86 per hectare in GPTDC, PI,474.27 per hectare in Acoje and Pl,024.40 per hectare in Taggat area. These positive trends and figures indicated the economically worthwhile investment of TSI operations following the same sets of conditions, data and assumptions as used in this study. In particular, the stumpage prices of the wood products in these localities were much higher than the log production costs.

In terms of BCR, all the study sites had values greater than unity, i.e. Sudecor with the highest at 1.59, GPTDC with 1.49, Acoje with 1.35 and Taggat with 1.24. A figure greater than unity further indicated the economic feasibility of TSI operations considering that the wood products out of the TSI removals from each of the stdy area were found to have economical uses and market values.

4.8.4 Sensitivity Analysis

TSI operations have been viewed by most timber companies as an expensive business venture that are subject to risk and uncertainty. In this regard, a sensitivity analysis is usually done to determine the changes in values of the economic criteria use~. with varying factors involved in the working assumptions. The factors tested

23

were the increase in interest (discount) rates, cost overrun, decrease in yield and fall in product prices.

Results of the sensitivity analysis exhibited negativePNW values and BCR less than unity with the cost overrun and decrease in average price of wood products. On the other hand, an increase in interest (discount) rate up to 25% and a corresponding 30% decrease in TSI yield did not affect the economic criteria beyond tolerable limits.

However, the 15% increase in log production costs in TSI areas would be uneconomical business venture as well as with 14% decrease in average market price of fuelwood; lumber and other wood products in the same study areas. Notably, these changes. in costs and prices of TSI materials have influenced the economic production of all study sites. Therefore, by keeping the average production costs of TSI areas at least 20% below the prevailing market or selling prices of materials removed during treatments, the TSI venture would definitely be an economic endeavor for timber companies and other entities dealing with this silvicultural operation.

5.0 Conclusions and Recommendations

From the results of this study, the following conclusions can be drawn:

1. The abundance of non-dipterocarps within residual dipterocarp stands have compelled the application of TSI treatments for better management of natural forest. There are more trees recorded in the lower diameter classes (10-20 cm dbh), and

. decreasing in their number or proportion with increasing diameter classes thereafter.

2. The TSI treatments through the removal of undesirable or unwanted trees, usually comprising of the non-dipterocarps or miscellaneous tree species, are now recognized to homogenize the stand composition with desired tree species and to improve the growth rates of the favored and selected trees left after logging operations.

3. The potential increment of the site can be manipulated to favor the growth and development of future crops or tree species groups, at the same time, reduce or minimize the share of less economically valuable trees within the residual stands. The PCTs shared the highest basal area and volume increments annually, particularly in plots with TSI treatments.

4. The application of TSI treatments timed at an early successional stages of development or in younger forest stands is appropriate to obtain higher probable growth responses of trees within the residual stands located even at different vegetational zones, elevations and climatic types. At the same time, the mortality rate for non-dipterocarps are higher in untreated plots due to adverse competition for growing space, while the ingrowth (reproduction) rate for favored and selected trees has increased in plots with TSI treatments.

24

... ,," .' .. , ... : .. : '."-' : '.:", ~. . . '. .. ':- . :' : ': . " ': .. '-',', '. ...... '.. '. ~. -: ... : .' .: .... -: '"::": '.' .' ~ .... '. ' ...

were the increase in interest (discount) rates, cost overrun, decrease in yield and fall in product prices.

Results of the sensitivity analysis exhibited negativePNW values and BCR less than unity with the cost overrun and decrease in average price of wood products. On the other hand, an increase in interest (discount) rate up to 25% and a corresponding 30% decrease in TSI yield did not affect the economic criteria beyond tolerable limits.

However, the 15% increase in log production costs in TSI areas would be uneconomical business venture as well as with 14% decrease in average market price of fuelwood; lumber and other wood products in the same study areas. Notably, these changes. in costs and prices of TSI materials have influenced the economic production of all study sites. Therefore, by keeping the average production costs of TSI areas at least 20% below the prevailing market or selling prices of materials removed during treatments, the TSI venture would definitely be an economic endeavor for timber companies and other entities dealing with this silvicultural operation.

5.0 Conclusions and Recommendations

From the results of this study, the following conclusions can be drawn:

1. The abundance of non-dipterocarps within residual dipterocarp stands have compelled the application of TSI treatments for better management of natural forest. There are more trees recorded in the lower diameter classes (10-20 cm dbh), and

. decreasing in their number or proportion with increasing diameter classes thereafter.

2. The TSI treatments through the removal of undesirable or unwanted trees, usually comprising of the non-dipterocarps or miscellaneous tree species, are now recognized to homogenize the stand composition with desired tree species and to improve the growth rates of the favored and selected trees left after logging operations.

3. The potential increment of the site can be manipulated to favor the growth and development of future crops or tree species groups, at the same time, reduce or minimize the share of less economically valuable trees within the residual stands. The PCTs shared the highest basal area and volume increments annually, particularly in plots with TSI treatments.

4. The application of TSI treatments timed at an early successional stages of development or in younger forest stands is appropriate to obtain higher probable growth responses of trees within the residual stands located even at different vegetational zones, elevations and climatic types. At the same time, the mortality rate for non-dipterocarps are higher in untreated plots due to adverse competition for growing space, while the ingrowth (reproduction) rate for favored and selected trees has increased in plots with TSI treatments.

24

•. ··.0' • pO' .. -......... -.... : .',.- ... : .. : . " ':,', ,'~.. '.' .. ,

5. The TSI removals or materials from the first and second treatments have contributed substantially to the economic production of the study areas, as they were found to have economical uses and market values.

6. The economic production are greatly affected by the fluctuating log production costs and prices of wood products at the time of TSI plot establishment and after ten years. The average market or selling prices of wood products have increased considerably during the course of this study, indicating the increasing domestic wood demands with declining supply of wood products in the local markets.

7. TSI operations can become a profitable business venture at a point when the average production costs are kept at least 20% below the prevailing market or selling prices of wood materials removed during treatments.

On the basis of the results obtained, the following recommendations are forwarded:

1. The preponderance of ingrowth (reproduction) has been observed in most treated residual stands, but if for any other reasons the residual stocking is inadequte, the re-stocking should concentrate more on the use of natural reproductions through enrichment planting or artificial forestation means. No amount of replanting can substitute for those dipterocarp wildlings and residuals already within the residual forests than starting from seeding and planting ..

2. There is a need to verify TSI results at the same or different vegetational zones, elevations and forest stand ages within each of the study site considering the inherent differences in soil types and silvicultural status of residual forest after logging activities.

3. TSI experiments should also consider the microenvironmental factors such light intensity, other soil factors, relative humidity, slopes and exposures. The effects can be monitored and evaluated in terms of growth responses between plots.

4. Economic analysis of TSI operations should also include other methods of extractions, such as carabao/manual method and truck/tractor with winch, to compare their efficiency and productivity at certain skidding or yarding distances, topography and terrain.

5. The current TSI guidelines should be amended accordingly based on the results of this study, particularly on the frequency or number of TSI treatments and the economic utilization or intermediate yield within the cutting cycle.

25

5. The TSI removals or materials from the first and second treatments have contributed substantially to the economic production of the study areas, as they were found to have economical uses and market values.

6. The economic production are greatly affected by the fluctuating log production costs and prices of wood products at the time of TSI plot establishment and after ten years. The average market or selling prices of wood products have increased considerably during the course of this study, indicating the increasing domestic wood demands with declining supply of wood products in the local markets.

7. TSI operations can become a profitable business venture at a point when the average production costs are kept at least 20% below the prevailing market or selling prices of wood materials removed during treatments.

On the basis of the results obtained, the following recommendations are forwarded:

1. The preponderance of ingrowth (reproduction) has been observed in most treated residual stands, but if for any other reasons the residual stocking is inadequte, the re-stocking should concentrate more on the use of natural reproductions through enrichment planting or artificial forestation means. No amount of replanting can substitute for those dipterocarp wildlings and residuals already within the residual forests than starting from seeding and planting ..

2. There is a need to verify TSI results at the same or different vegetational zones, elevations and forest stand ages within each of the study site considering the inherent differences in soil types and silvicultural status of residual forest after logging activities.

3. TSI experiments should also consider the microenvironmental factors such light intensity, other soil factors, relative humidity, slopes and exposures. The effects can be monitored and evaluated in terms of growth responses between plots.

4. Economic analysis of TSI operations should also include other methods of extractions, such as carabao/manual method and truck/tractor with winch, to compare their efficiency and productivity at certain skidding or yarding distances, topography and terrain.

5. The current TSI guidelines should be amended accordingly based on the results of this study, particularly on the frequency or number of TSI treatments and the economic utilization or intermediate yield within the cutting cycle.

25

ACKNOWLEDGEMENT

The author of this study, through the Forest Management Bureau (FMB) under the Department of Environment and Natural Resources (DENR), is very grateful to the International Tropical Timber Organization (ITTO) fcir funding this Project, as well as to the Philippine-German Integrated Rainforest Management Project (IRMP) for the use of the TSI data and the cooperating working units or timber companies, including those people involved in the establishment, remeasurement and maintenance of the TSI sample plots.

26

'. ' .- '-~: .... -;":~', ~. \ '. -" .. :'" .. - .:-~'.~.~ . .' ... ::. ~ , .'.::.', -:; .. ;':~. ,- . ~ :-' .. :;.:. ~ ';'.--:' -: ....... ---;: .:", ~_ : .. ~ '."~ ': .. ~'-".~ ... ~'. ~'.~;;:":~ ."':';'. '::-:~"-:~'>'.~:::':'-;-.~.~-;'::~~ ~'.~y'.:.:"_'.'.~.::.'--~.~ .~:l::::'·:~:·-:~~:··;:·~;::~::~:~:::'::~;'~;~~'.:::

ACKNOWLEDGEMENT

The author of this study, through the Forest Management Bureau (FMB) under the Department of Environment and Natural Resources (DENR), is very grateful to the International Tropical Timber Organization (ITTO) fcir funding this Project, as well as to the Philippine-German Integrated Rainforest Management Project (IRMP) for the use of the TSI data and the cooperating working units or timber companies, including those people involved in the establishment, remeasurement and maintenance of the TSI sample plots.

26

. "

REFERENCES

ABDUL RAHMAN, K., 1. SHAHRULZAMAN and G. WEINLAND. 1991. Impacts of selective logging on some aspects of stocking and growth of a hill dipterocarp forest in Peninsular Malaysia. Paper presented at the ASEAN Seminar on Land-use Decisions and Policies, Penang, Malaysia. 10 pp.

ABRAHAM, F.B.,JR. 1982. Costs of TSI operations in Nasipit Lumber Company (NALCO), Tungao, Butuan City. Timber Management Plan (TMP) of NALCO.

BAUR, G.N. 1964. Rainforest treatment. Unasylva. 18(1):18-28.

CRUZ, C.A. 1982. Economic. efficiency of the selective logging system in selected areas in the Philippines. Ph.D Dissertation (Unpublished). UPLBCF College, Laguna.

DOMINGO,LL. 1979. Regeneration and treatments of dipterocarp forest in Southeast Asia. Paper presented at the Dipterocarp Management Seminar. Ambassador Hotel, Manila.

DOMINGO,I.L. 1982. Timber stand improvement in Philippine dipterocarp forests. The Philippine Lumberman. 28(4): 16-17.

FAUSTINO, D.E. and E.M. BASCUG. 1977. TSI in binuang (Octomeles sumatrana) in natural stands. Sylvatrop, Phil. For. Res. Journal. 2(2): 111-116.

FMB, 1993.· Philippine Forestry Statistics. Published by the Forest Management Bureau (FMB), Diliman, Quezon City, Philippines. 80 pp.

MANILA, A.C. and H.J. WOELL. 1985. TSI : A solution to the problem of dwindling dipterocarps. Tropical Forests. 2(2): 28-32.

MANILA, A.C. 1989. Growth responses and Economic production of residual dipterocarp stands to timber stand improvement (TSI) treatments. Ph.D Dissertation (Published), UPLB Graduate School, College, Laguna. 185 pp.

MAURICIO, F.P. 1967. Timber stand improvement in Philippine dipterocarp residual forests for the first five years after tractor logging. The Philippine Lumberman. 13(6): 31-39.

MAURICIO, F.P. 1980. Current research thrusts in timber stand improvement. Paper presented during the Philippine For. Soc. Symposium. FORI, College, Laguna.

REVILLA, A.V., JR. 1979. Critical issues in forest resources management in the Philippines. Inaugural lecture for SEARCA Professorial Chair in FRM. UPLB

_'" College of Forestry, College, Laguna.

27

REFERENCES

ABDUL RAHMAN, K., 1. SHAHRULZAMAN and G. WEINLAND. 1991. Impacts of selective logging on some aspects of stocking and growth of a hill dipterocarp forest in Peninsular Malaysia. Paper presented at the ASEAN Seminar on Land-use Decisions and Policies, Penang, Malaysia. 10 pp.

ABRAHAM, F.B.,JR. 1982. Costs of TSI operations in Nasipit Lumber Company (NALCO), Tungao, Butuan City. Timber Management Plan (TMP) of NALCO.

BAUR, G.N. 1964. Rainforest treatment. Unasylva. 18(1):18-28.

CRUZ, C.A. 1982. Economic. efficiency of the selective logging system in selected areas in the Philippines. Ph.D Dissertation (Unpublished). UPLBCF College, Laguna.

DOMINGO,LL. 1979. Regeneration and treatments of dipterocarp forest in Southeast Asia. Paper presented at the Dipterocarp Management Seminar. Ambassador Hotel, Manila.

DOMINGO, LL. 1982. Timber stand improvement in Philippine dipterocarp forests. The Philippine Lumberman. 28(4): 16-17.

FAUSTINO, D.E. and E.M. BASCUG. 1977. TSI in binuang (Octomeles sumatrana) in natural stands. Sylvatrop, Phil. For. Res. Journal. 2(2): 111-116.

FMB, 1993.· Philippine Forestry Statistics. Published by the Forest Management Bureau (FMB), Diliman, Quezon City, Philippines. 80 pp.

MANILA, A.C. and H.J. WOELL. 1985. TSI : A solution to the problem of dwindling dipterocarps. Tropical Forests. 2(2): 28-32.

MANILA, A.C. 1989. Growth responses and Economic production of residual dipterocarp stands to timber stand improvement (TSI) treatments. Ph.D Dissertation (Published), UPLB Graduate School, College, Laguna. 185 pp.

MAURICIO, F.P. 1967. Timber stand improvement in Philippine dipterocarp residual forests for the first five years after tractor logging. The Philippine Lumberman. 13(6): 31-39.

MAURICIO, F.P. 1980. Current research thrusts in timber stand improvement. Paper presented during the Philippine For. Soc. Symposium. FORI, College, Laguna.

REVILLA, A.V., JR. 1979. Critical issues in forest resources management in the Philippines. Inaugural lecture for SEARCA Professorial Chair in FRM. UPLB

_'" College of Forestry, College, Laguna.

27

REYES, M.R. 1978. Possibilities of increasing the yields of tropical rainforest in the Philippines. The Malay. Forester. 41(2): 167-170.

REYES, M.R. 1994. Report on work accomplished under the FMB-ERDB TSI Project: Summary of data on market prices of wood products. ERDB Los Banos, Laguna. 4 pp.

REYES, M.R. and E.T. TAGUDAR. 1964. TSI guide for dipterocarp secondary forest. The Philippine Lumberman. 10(1): 58-64.

SIAPNO, LB. 1970. Handbook of selective logging in the Philippines. Bureau of Printing. Manila.

TAGUDAR, E.T. 1967. The response of dipterocarp seedlings when released from competing vegetation. Forestry Leaves. 28(1-2): p. 47.

TAGUDAR, E.T. 1979. Enrichment planting with fast-growing species: A new silvicultural tool for increasing yield of cut-over areas. Paper presented at the Dipterocarp Management Seminar. Ambassador Hotel, Manila.

TOMBOC, C.C. 1987. An evaluation of selective logging as a sustained-yield timber management system. Ph.D. Dissertation (Unpublished), UPLB Graduate School, College, Laguna.

UEBELHOER, K and R. ABALUS. 1991. Enrichment planting experiments in inadequately-stocked areas within Surigao Development Corporation (SUDECOR) concession. Paper presented at the Philippine-German Project Seminar. Asian Institute of Technology, Diliman, Quezon City.

UTLEG, J.L. and M.R. REYES. 1967. Evolution and trends in silvicultural techniques applied to natural forest in the Philippines. The Philippine Lumberman. 13(4): 32-35,39-44.

VERACION, A.G. 1987. Investment incentives to promote a nationwide TSI program. The Philippine Lumberman. 33(4): 18-25.

WEIDELT, H.J. and V.S. BANAAG. 1982. Aspect of management and silviculture of Philippine dipterocarp forests. Eschborn, West Germany. GTZ Publication No. 132. 302 pp.

WHITMORE, T.e. 1975. Tropical forest of the Far East. Clarendon Press, Oxford, England.

YONG, T.C. 1990. Growth and yield of a mixed dipterocarp forest in Peninsular Malaysia. Fellowship Report. ASEAN Institute of Forest Management (AIFM), Kuala Lumpur, Malaysia. 160 pp.

28

..... ;:~~. _ ~.' . '. ~ ':':' .-: :: .:::: .... . '. ~ .. '; .-<; ::: .. ' .. :,' .. : .' .. ::." ';: .. -- ;! -.......... _ ~.: ,-: ~ . . . ...... : .. r:. ~ ... ' ...... , : '. ',; :. ::', :~-~. ::::.~.~~ .. ~'7.-:. ~~ .. ~~: .. ~~:: .. -:-: :-:-;':::::':-~;:'.\"'~.::~:';:~::.

REYES, M.R. 1978. Possibilities of increasing the yields of tropical rainforest in the Philippines. The Malay. Forester. 41(2): 167-170.

REYES, M.R. 1994. Report on work accomplished under the FMB-ERDB TSI Project: Summary of data on market prices of wood products. ERDB Los Banos, Laguna. 4 pp.

REYES, M.R. and E.T. TAGUDAR. 1964. TSI guide for dipterocarp secondary forest. The Philippine Lumberman. 10(1): 58-64.

SIAPNO, LB. 1970. Handbook of selective logging in the Philippines. Bureau of Printing. Manila.

TAGUDAR, E.T. 1967. The response of dipterocarp seedlings when released from competing vegetation. Forestry Leaves. 28(1-2): p. 47.

TAGUDAR, E.T. 1979. Enrichment planting with fast-growing species: A new silvicultural tool for increasing yield of cut-over areas. Paper presented at the Dipterocarp Management Seminar. Ambassador Hotel, Manila.

TOMBOC, C.C. 1987. An evaluation of selective logging as a sustained-yield timber management system. Ph.D. Dissertation (Unpublished), UPLB Graduate School, College, Laguna.

UEBELHOER, K and R. ABALUS. 1991. Enrichment planting experiments in inadequately-stocked areas within Surigao Development Corporation (SUDECOR) concession. Paper presented at the Philippine-German Project Seminar. Asian Institute of Technology, Diliman, Quezon City.

UTLEG, J.L. and M.R. REYES. 1967. Evolution and trends in silvicultural techniques applied to natural forest in the Philippines. The Philippine Lumberman. 13(4): 32-35,39-44.

VERACION, A.G. 1987. Investment incentives to promote a nationwide TSI program. The Philippine Lumberman. 33(4): 18-25.

WEIDELT, H.J. and V.S. BANAAG. 1982. Aspect of management and silviculture of Philippine dipterocarp forests. Eschborn, West Germany. GTZ Publication No. 132. 302 pp.

WHITMORE, T.e. 1975. Tropical forest of the Far East. Clarendon Press, Oxford, England.

YONG, T.C. 1990. Growth and yield of a mixed dipterocarp forest in Peninsular Malaysia. Fellowship Report. ASEAN Institute of Forest Management (AIFM), Kuala Lumpur, Malaysia. 160 pp.

28

APPENDICES

Appendix Table 1. Analysis of variance of original residual stand (number of stems per hectare).

SV DF : SS MS F

1. Taggat

A) Dipterocarp Treatment 1 333,333.70 333,333.70 1.15ns

Error 10 28,889,583.30 289,958.33 Total 11 3,222,917.00

B) Non-dipt. Treatment 1 50,052.07 50,052.07 1.20ns

Error 10 416,770.83 41,667.08 Total 11 466,822.90

2. Acoje

A) Dipterocarp Treatment 1 7,500.03 7,500.03 0.81 ns

Error 10 92,916.67 9,291.67 Total 11 100,416.70

B) Non-dipt. Treatment 30,000.30 30,000.30 0.31ns

Error 10 982,291.70 98,229.17 Total 11 1,012,292.00

3. Sudecor

A) Dipterocarp Treatment 574,218.70 574,218.70 5.36* Error 10 1,070,937.50 107,093.75 Total 11 1,645,156.20

B) Non-dipt. Treatment 367,500.30 367,500.30 2.53ns

Error 10 1,452,916.70 145,291.67 Total 11 1,820,417.00

4. GPTDC

A) Dipterocarp Treatment 163,333.37 163,333.37 5.73*

Error 10 285,208.33 28,520.83 Total 11 448,541.70

B) Non-dipt. Treatment 151,875.30 151,875.30 3.41 ns

Error 10 444,791.70 44,479.17 Total 11 596,667.00

* significant at 0.05 ns not significant

29

APPENDICES

Appendix Table 1. Analysis of variance of original residual stand (number of stems per hectare).

SV DF : SS MS F

1. Taggat

A) Dipterocarp Treatment 1 333,333.70 333,333.70 1.15ns

Error 10 28,889,583.30 289,958.33 Total 11 3,222,917.00

B) Non-dipt. Treatment 1 50,052.07 50,052.07 1.20ns

Error 10 416,770.83 41,667.08 Total 11 466,822.90

2. Acoje

A) Dipterocarp Treatment 1 7,500.03 7,500.03 0.81 ns

Error 10 92,916.67 9,291.67 Total 11 100,416.70

B) Non-dipt. Treatment 30,000.30 30,000.30 0.31ns

Error 10 982,291.70 98,229.17 Total 11 1,012,292.00

3. Sudecor

A) Dipterocarp Treatment 574,218.70 574,218.70 5.36* Error 10 1,070,937.50 107,093.75 Total 11 1,645,156.20

B) Non-dipt. Treatment 367,500.30 367,500.30 2.53ns

Error 10 1,452,916.70 145,291.67 Total 11 1,820,417.00

4. GPTDC

A) Dipterocarp Treatment 163,333.37 163,333.37 5.73* Error 10 285,208.33 28,520.83 Total 11 448,541.70

B) Non-dipt. Treatment 151,875.30 151,875.30 3.41 ns

Error 10 444,791.70 44,479.17 Total 11 596,667.00

* significant at 0.05 ns not significant

29

Appendix Table 2. Analysis of variance of original residual stand (basal area per hectare).

sv OF SS MS F

1. Taggat

A) Dipterocarp Treatment 1 15.07 15.07 0.14ns

Error 10 1064.10 106.41 Total 11 1079.17

B) . Non-dipt. Treatment 1.87 1.87 0.08ns

Error 10 228.65 22.86 Total 11 230.52

2. Acoje

A) Dipterocarp Treatment 0.94 0.94 0.02ns

Error 10 481.30 48.13 Total 11 482.24

B) Non-dipt. Treatment 1 30.80 30.80 O.17ns

Error 10 263.23 26.32 Total 11 294.03

3. Sudecor

A) Dipterocarp Treatment 7.01 7.01 0.17ns

Error 10 415.44 41.54 Total 11 442.45

B) Non-dipt. Treatment 1 28.75 28.75 0.33ns

Error 10 868.56 86.86 Total 11 897.31

4. GPTOC

A) Dipterocarp Treatment 70.69 70.69 1.19ns

Error 10 595.71 59.57 Total 11 666.40

B) Non-dipt. Treatment 51.98 51.98 1.7ns

Error 10 304.61 30.46 Total 11 356.59

ns not significant

30

- ," ••••..• "_"0" .-,' • :'-•• ;:~-.j_:. ,",. : --: !~.: '_:";"~: .• ~:'; . .,-,.'~.~" ,.::: .;~.~~-:-~ ~~: ·~·:·~:--'·'-::~'::--~·4 '":'. ""-.' .... ~.~ -:. .:~ .. ~r .. :::'i ... ,~~~~;;~··i;:. -:.'''{:;'' ,:-.:~:;-:. : .... ~-;. .... ~; .~-..:~~~;.··7:~~-:·~~ ::';:~"'~~I:·.··~·~c,.::~::;";";;:,::;\~~"';_ ",-. Y

Appendix Table 2. Analysis of variance of original residual stand (basal area per hectare).

sv OF SS MS F

1. Taggat

A) Dipterocarp Treatment 1 15.07 15.07 0.14ns

Error 10 1064.10 106.41 Total 11 1079.17

B) . Non-dipt. Treatment 1.87 1.87 0.08ns

Error 10 228.65 22.86 Total 11 230.52

2. Acoje

A) Dipterocarp Treatment 0.94 0.94 0.02ns

Error 10 481.30 48.13 Total 11 482.24

B) Non-dipt. Treatment 1 30.80 30.80 O.17ns

Error 10 263.23 26.32 Total 11 294.03

3. Sudecor

A) Dipterocarp Treatment 7.01 7.01 0.17ns

Error 10 415.44 41.54 Total 11 442.45

B) Non-dipt. Treatment 1 28.75 28.75 0.33ns

Error 10 868.56 86.86 Total 11 897.31

4. GPTOC

A) Dipterocarp Treatment 70.69 70.69 1.19ns

Error 10 595.71 59.57 Total 11 666.40

B) Non-dipt. Treatment 51.98 51.98 1.7ns

Error 10 304.61 30.46 Total 11 356.59

ns not significant

30

Appendix Table 3. Analysis of variance of original residual stand (volume per hectare).

SV OF SS MS F

1. Taggat

A) Dipterocarp Treatment 1 2,945.33 15.07 0.38ns

Error 10 78.026.79 106.41 Total 11 80,972.12

B) Non-dipt. Treatment 1 2,193.76 2,193.76 1.36ns

Error 10 16,083.88 1,608.39 Total 11 18,277.64

2. Acoje

A) Dipterocarp Treatment 1 679.69 679.69 0.06ns

Error 10 112,023.06 11,202.31 Total 11 112,277.64

B) Non-dipt. Treatment 1 1,856.30 1,856.30 0.06ns

Error 10 49,948.72 4,994.87 Total 11 51,805.02

3. Sudecor

A) Dipterocarp Treatment 1 1.69 1.69 0.0002ns

Error 10 82,693.61 8,269.36 Total 11 82,695.30

B) Non-dipt. Treatment 1 338.67 338.67 0.07ns

Error 10 49,884.13 4,988.41 Total 11 50,222.80

4. GPTOC

A) Dipterocarp Treatment 1 4,190.67 4,190.67 0.46ns

Error 10 91,040.97 9,104.10 Total 11 95,231.64

B) Non-dipt. Treatment 1 18,921.03 18,921.03 2.24ns

Error 10 84,420.53 8,442.05 Total 11 103,341.56

ns not significant

31

Appendix Table 3. Analysis of variance of original residual stand (volume per hectare).

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 1 2,945.33 15.07 0.38ns

Error 10 78.026.79 106.41 Total 11 80,972.12

B) Non-dipt. Treatment 1 2,193.76 2,193.76 1.36ns

Error 10 16,083.88 1,608.39 Total 11 18,277.64

2. Acoje

A) Dipterocarp Treatment 1 679.69 679.69 0.06ns

Error 10 112,023.06 11,202.31 Total 11 112,277.64

B) Non-dipt. Treatment 1 1,856.30 1,856.30 0.06ns

Error 10 49,948.72 4,994.87 Total 11 51,805.02

3. Sudecor

A) Dipterocarp Treatment 1 1.69 1.69 0.0002ns

Error 10 82,693.61 8,269.36 Total 11 82,695.30

B) Non-dipt. Treatment 1 338.67 338.67 0.07ns

Error 10 49,884.13 4,988.41 Total 11 50,222.80

4. GPTOC

A) Dipterocarp Treatment 1 4,190.67 4,190.67 0.46ns

Error 10 91,040.97 9,104.10 Total 11 95,231.64

B) Non-dipt. Treatment 1 18,921.03 18,921.03 2.24ns

Error 10 84,420.53 8,442.05 Total 11 103,341.56

ns not significant

31

Appendix Table 4. Analysis of variance of initial number of stems per hectare in each site.

SV OF SS MS F

1. Taggat

A) Oipterocarp Treatment 87,552.20 87,552.20 0.39ns

Error 10 2,230,520.80 223,052.10 Total 11 2,318,073.00

B) Non-dipt. Treatment 105,468.70 105,468.70 2.76ns

Error 10 382,187.50 38,218.80 Total 11 487,656.20

2. Acoje

A) Dipterocarp Treatment 16,875.00 16,875.00 1.26ns

Error 10 134,166.70 13,416.70 Total 11 151,041.70

B) Non-dipt. Treatment 255,208.30 255,208.30 2.92ns

Error 10 873,541.70 87,354.20 Total 11 1,128,750.00

3. Sudecor

A) Dipterocarp Treatment 1 440,833.40 440,833.40 4.92ns • Error 10 895,208.30 89,520.80 Total 11 1,336,041.70

B) Non-dipt. Treatment 1,080,000.30 1,080,000.3 6.50* Error 10 1,661,666.70 166,166.7 Total 11 2,741,667.00

4. GPTOC

A) Dipterocarp Treatment 1 83,333.30 83,333.30 3.24ns

Error 10 257,291.70 25,729.20 Total 11 340,625.00

B) Non-dipt. Treatment 120,000.30 120,000.30 3.36ns

Error 10 357,291.70 35,729.20 Total 11 477,292.00

* significant at 0.05 ns not significant

32

. : .-', • :: . .- , ~'h-~ .. ~:.: .; .-; .••. - .. ' . ': . '" '; • ~. :-. ':-', '"'.:.. : • '. ~.' . ~ . -.", -. '. 4 .:", :'::""4~':' ," : '::-. :c.:..: .. :~ .• :-;:--:-., '-,".~;':".:-;:::-;'~::"::: -::-:. ': ..... : .-;',' :: .. ~.; ;:".-":. -', .• ;", '. ';'.;, ~ ~ -;--.-4 -:;~: .• ,;; r.'~ ' ...... : .. ~.; ."~-~-:.~.~ .. " ;" ':"~~~~:'_' •• ;\:.-;._ r.::l

Appendix Table 4. Analysis of variance of initial number of stems per hectare in each site.

SV OF SS MS F

1. Taggat

A) Oipterocarp Treatment 87,552.20 87,552.20 0.39ns

Error 10 2,230,520.80 223,052.10 Total 11 2,318,073.00

B) Non-dipt. Treatment 105,468.70 105,468.70 2.76ns

Error 10 382,187.50 38,218.80 Total 11 487,656.20

2. Acoje

A) Dipterocarp Treatment 16,875.00 16,875.00 1.26ns

Error 10 134,166.70 13,416.70 Total 11 151,041.70

B) Non-dipt. Treatment 255,208.30 255,208.30 2.92ns

Error 10 873,541.70 87,354.20 Total 11 1,128,750.00

3. Sudecor

A) Dipterocarp Treatment 1 440,833.40 440,833.40 4.92ns • Error 10 895,208.30 89,520.80 Total 11 1,336,041.70

B) Non-dipt. Treatment 1,080,000.30 1,080,000.3 6.50* Error 10 1,661,666.70 166,166.7 Total 11 2,741,667.00

4. GPTOC

A) Dipterocarp Treatment 1 83,333.30 83,333.30 3.24ns

Error 10 257,291.70 25,729.20 Total 11 340,625.00

B) Non-dipt. Treatment 120,000.30 120,000.30 3.36ns

Error 10 357,291.70 35,729.20 Total 11 477,292.00

* significant at 0.05 ns not significant

32

Appendix Table 5. Analysis of variance of number of stems per hectare in each site after ten years.

SV OF : SS MS F

1. Taggat

Al Oipterocarp Treatment 1 292,968.75 292,968.75 1.22ns

Error 10 2,395,104.17 239,510.42 Total 11 2,688,072.92

B) Non-dipt. Treatment 1 15,052.09 15,052.09 0.45ns

Error 10 336,770.83 33,677.08 Total 11 351,822.92

2. Acoje

A) Oipterocarp Treatment 1 7,500.00 7,500.00 0.58ns

Error 10 128,541.67 12,854.17 Total 11 136,041.67

B) Non-dipt. Treatment 1 120,000.00 120,000.00 1.70ns

Error 10 706,666.67 70,666.67 Total 11 826,666.67

3. Sudecor

A) Dipterocarp Treatment 1 1,350,052.09 1,350,052.0 17.55**

Error 10 769,270.83 76,927.08 Total 11 2,119,322.92

B) Non-dipt. Treatment 30,000.00 30,000.00 0.12ns

Error 10 2,542,916.67 254,291.67 Total 11 2,572,916.67

4. GPTOC

A) Dipterocarp Treatment 563,333.34 563,333.34 13.53**

Error 10 416,458.33 41,645.83 Total 11 979,791.67

B) Non-dipt. Treatment 169,218.83 169,218.83 5.71 *

Error 10 296,354.09 29,635.41 Total 11 465,572.92

* significant at 0.05 * * significant at 0.01 ns not significant

33

•• ';" _ .. _ .... !. ... :. ":.'" .. ~:~.:~:' ~":,,,: .~ :,:-~_':~.: __ .:' '.'-":-~:'.':::.' .• ~ :'":_,;"_:',' ••. ..-, ~._".~ ... ~ ••. " .• , ••• ' "-;'"". -:-7.-.-.-:-.- ;':;T.'';:.:;. ..... '._ -::~.~,~ •• -\~~.:-..-.,.",.:.":,.-:.: .... ~, ... -. .•• -~ . • -r:J:::"-"; • '.:'",-.~--•• ; -'C",: r'~.r'.;"_--::-:-.":::".~·;.::",,,!":-:; •. -"-~~t::·'7::.:··!~ .. r<f1::""".~-·:·"'r.:~>c.'~r-=-

Appendix Table 5. Analysis of variance of number of stems per hectare in each site after ten years.

SV OF : SS MS F

1. Taggat

Al Oipterocarp Treatment 1 292,968.75 292,968.75 1.22ns

Error 10 2,395,104.17 239,510.42 Total 11 2,688,072.92

B) Non-dipt. Treatment 1 15,052.09 15,052.09 0.45ns

Error 10 336,770.83 33,677.08 Total 11 351,822.92

2. Acoje

A) Oipterocarp Treatment 1 7,500.00 7,500.00 0.58ns

Error 10 128,541.67 12,854.17 Total 11 136,041.67

B) Non-dipt. Treatment 1 120,000.00 120,000.00 1.70ns

Error 10 706,666.67 70,666.67 Total 11 826,666.67

3. Sudecor

A) Dipterocarp Treatment 1 1,350,052.09 1,350,052.0 17.55**

Error 10 769,270.83 76,927.08 Total 11 2,119,322.92

B) Non-dipt. Treatment 30,000.00 30,000.00 0.12ns

Error 10 2,542,916.67 254,291.67 Total 11 2,572,916.67

4. GPTOC

A) Dipterocarp Treatment 563,333.34 563,333.34 13.53**

Error 10 416,458.33 41,645.83 Total 11 979,791.67

B) Non-dipt. Treatment 169,218.83 169,218.83 5.71 *

Error 10 296,354.09 29,635.41 Total 11 465,572.92

* significant at 0.05

** significant at 0.01 ns not significant

33

Appendix Table 6. Analysis of variance of initial and final (after ten years) number of stems per hectare among TSI sites.

SV OF SS MS F

I. At establishment

Treatment 1 135,720.50 135,720.50 1.40ns

Error 6 583,267.50 97,211.25 Total 7 718,988.00

11. After ten years

Treatment 830,116.13 830,116.13 0.73ns

Error 6 6,828,516.75 1,138,086.1 Total 7 7,658,632.88

ns not significant

Appendix Table 7. Analysis of variance of mean total heights oftrees found among TSI sites at establishment and after ten years.

SV DF SS MS F

I. At establishment

A) Dipterocarp Treatment 1 0.5 0.5 0.08ns

Error 6 36.0 6.0 Total 7 36.5

B) Non-dipterocarp Treatment 1 29.7 29.7 2.43ns

Error 6 73.3 12.2 Total 7 102.9

11. After ten years

A) Dipterocarp Treatment 1 2.5 2.5 O.13ns

Error 6 114.2 19.0 Total 7 116.7

B) Non-dipterocarp Treatment 1 31.7 31.7 2.46ns

Error 6 77.2 12.9 Total 7 108.9

ns not significant

34

, >

Appendix Table 6. Analysis of variance of initial and final (after ten years) number of stems per hectare among TSI sites.

SV OF : SS MS F

I. At establishment

Treatment 1 135,720.50 135,720.50 1.40ns

Error 6 583,267.50 97,211.25 Total 7 718,988.00

11. After ten years

Treatment 830,116.13 830,116.13 0.73ns

Error 6 6,828,516.75 1,138,086.1 Total 7 7,658,632.88

ns not significant

Appendix Table 7. Analysis of variance of mean total heights oftrees found among TSI sites at establishment and after ten years.

SV DF SS MS F

I. At establishment

A) Dipterocarp Treatment 1 0.5 0.5 0.08ns

Error 6 36.0 6.0 Total 7 36.5

B) Non-dipterocarp Treatment 1 29.7 29.7 2.43ns

Error 6 73.3 12.2 Total 7 102.9

11. After ten years

A) Dipterocarp Treatment 1 2.5 2.5 O.13ns

Error 6 114.2 19.0 Total 7 116.7

B) Non-dipterocarp Treatment 1 31.7 31.7 2.46ns

Error 6 77.2 12.9 Total 7 108.9

ns not significant

34

>

Appendix Table 8. Analysis of variance of mean total heights of trees per hectare in each site at establishment period.

SV OF : SS MS F

1. Taggat

Al Dipterocarp Treatment 6.90 6.90 0.88ns

Error 10 78.67 7.88 Total 11 85.57

SI Non-dipt. Treatment 13.23 13.23 4.45ns

Error 10 29.68 2.97 Total 11 42.91

2. Acoje

Al Dipterocarp Treatment 1 0.14 0.14 0.01 ns

Error 10 160.93 16.09 Total 11 161.07

SI Non-dipt. Treatment 1 29.14 29.14 4.71 ns

Error 10 61.87 6.19 Total 11 91.01

3. Sudecor

Al Dipterocarp Treatment 6.46 6.46 0.24ns • Error 10 273.20 27.32 Total 11 279.66

SI Non-dipt. Treatment 143.52 143.52 9.00* Error 10 159.42 15.94 Total 11 302.94

4. GPTOC

Al Dipterocarp Treatment 0.86 0.86 0.04ns

Error 10 195.64 19.56 Total 11 196.50

SI Non-dipt. Treatment 32.34 32.34 6.78* Error 10 47.67 4.77 Total 11 80.01

* significant at 0.05 ns not significant

35

. ;. .•. _.~ .. , :.~".-:'::'." •. \:" .A; ..... ;._.:·~_,.~,.~·~·~~·~··,A'; •. :. 'f.-, ••.• _;,~. :-. -::-·o:"";:-::.: .. ~,<;-rr:.'":· .. '·.";'''·'':''':·'·'''''''··''''?'''''-'''''''''''·''''''''-.~)-:::·:~'';'':''.!'l::~·';r.o':'"''':''''' ... v.-''"''"'7,~~<!:~~.·.,.....,-.. ~r·- .... r-·'' .,-.---.--::-~.,.-.....

Appendix Table 8. Analysis of variance of mean total heights of trees per hectare in each site at establishment period.

SV OF : SS MS F

1. Taggat

Al Dipterocarp Treatment 6.90 6.90 0.88ns

Error 10 78.67 7.88 Total 11 85.57

SI Non-dipt. Treatment 13.23 13.23 4.45ns

Error 10 29.68 2.97 Total 11 42.91

2. Acoje

Al Dipterocarp Treatment 1 0.14 0.14 0.01 ns

Error 10 160.93 16.09 Total 11 161.07

SI Non-dipt. Treatment 1 29.14 29.14 4.71 ns

Error 10 61.87 6.19 Total 11 91.01

3. Sudecor

Al Dipterocarp Treatment 6.46 6.46 0.24ns • Error 10 273.20 27.32 Total 11 279.66

SI Non-dipt. Treatment 143.52 143.52 9.00* Error 10 159.42 15.94 Total 11 302.94

4. GPTOC

Al Dipterocarp Treatment 0.86 0.86 0.04ns

Error 10 195.64 19.56 Total 11 196.50

SI Non-dipt. Treatment 32.34 32.34 6.78* Error 10 47.67 4.77 Total 11 80.01

* significant at 0.05 ns not significant

35

Appendix Table 9. Analysis of variance of initial basal area per hectare in each TSI study site.

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 12.86 12.86 0.16ns

Error 10 780.85 78.08 Total 11 793.71

B) Non-dipt. Treatment 1 11.31 11.31 0.97ns

Error 10 116.86 11.69 Total 11 128.17

2. Acoje

A) Dipterocarp Treatment 12.58 12.58 0.37ns

Error 10 408.02 40.80 Total 11 420.60

B) Non-dipt. Treatment 99.48 99.48 3.96ns

Error 10 251.39 25.14 Total 11 350.87

3. Sudecor

A) Dipterocarp Treatment 4.81 4.81 0.12ns • Error 10 406.66 40.67 Total 11 411.47

B) Non-dipt. Treatment 543.38 543.38 5.69* Error 10 954.67 95.47 Total 11 1,498.05

4. GPTOC

A) Dipterocarp Treatment 1 66.00 66.00 1.01 ns

Error 10 598.45 59.84 Total 11 664.45

B) Non-dipt. Treatment 1 98.58 98.58 3.32ns

Error 10 296.95 29.69 Total 11 395.53

* significant at 0.05 ns not significant

36

Appendix Table 9. Analysis of variance of initial basal area per hectare in each TSI study site.

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 12.86 12.86 0.16ns

Error 10 780.85 78.08 Total 11 793.71

B) Non-dipt. Treatment 1 11.31 11.31 0.97ns

Error 10 116.86 11.69 Total 11 128.17

2. Acoje

A) Dipterocarp Treatment 12.58 12.58 0.37ns

Error 10 408.02 40.80 Total 11 420.60

B) Non-dipt. Treatment 99.48 99.48 3.96ns

Error 10 251.39 25.14 Total 11 350.87

3. Sudecor

A) Dipterocarp Treatment 4.81 4.81 0.12ns • Error 10 406.66 40.67 Total 11 411.47

B) Non-dipt. Treatment 543.38 543.38 5.69* Error 10 954.67 95.47 Total 11 1,498.05

4. GPTOC

A) Dipterocarp Treatment 1 66.00 66.00 1.01 ns

Error 10 598.45 59.84 Total 11 664.45

B) Non-dipt. Treatment 1 98.58 98.58 3.32ns

Error 10 296.95 29.69 Total 11 395.53

* significant at 0.05 ns not significant

36

Appendix Table 10. Analysis of variance of mean basal area per hectare in each TSI study site after ten years.

SV OF : SS MS F

1. Taggat

A) Oipterocarp Treatment 1 105.02 105.02 0.85ns

Error 10 1,229.05 122.91 Total 11 1,334.07

S) Non-dipt. Treatment 1 10.08 10.08 0.40ns

Error 10 248.92 24.89 Total 11 259.00

2. Acoje

A) Oipterocarp Treatment 1 3.26 3.26 0.07ns

Error 10 454.81 45.48 Total 11 458.07

S) Non-dipt. Treatment 1 80.09 80.09 2.25ns

Error 10 317.83 31.78 Total 11 397.92

3. Sudecor

A) Dipterocarp Treatment 1 527.19 527.19 9.24** Error 10 571.26 57.13 Total 11 1,099.14

S) Non-dipt. Treatment 315.19 315.19 1.68ns

Error 10 1,877.16 187.72 Total 11 2,192.35

4. GPTOC

A) Dipterocarp Treatment 231.88 231.88 3.76ns

Error 10 615.80 61.58 Total 11 847.68

S) Non-dipt. Treatment 1 268.38 268.38 11.05** Error 10 242.76 24.28 Total 11 511.14

* significant at 0.05 * * significant at 0.01 ns not significant

37

',' • _ ':.: _, .• ,:'. -:;-,":~: ._.~: ',.:-. ;~:.. :~~;O;- :-..':'," t.' .: . \ ' .. '"; ... ~ .. :' . :. ~ .. ~ ... ~ . _.~ ~ .. -.... _po;'~' ':::::~":"~';~"".-".,;-; ..•• ~;.~~. ~·"i"_,":r~::!7,O-l''.~'-:o··.o; ... '''·~'':·~''''i·~'''':~·~''C':;:::'::'::~ ':_:':~~~~':·'~-:':-~~·l~;!-'-~~~-;·'-f.,." ... c;::~_",:r'~..,.,;,,..:: • ., ... -., -:-:0:;,' -;:- .:-::--~. - .",

Appendix Table 10. Analysis of variance of mean basal area per hectare in each TSI study site after ten years.

SV OF : SS MS F

1. Taggat

A) Oipterocarp Treatment 1 105.02 105.02 0.85ns

Error 10 1,229.05 122.91 Total 11 1,334.07

S) Non-dipt. Treatment 1 10.08 10.08 0.40ns

Error 10 248.92 24.89 Total 11 259.00

2. Acoje

A) Oipterocarp Treatment 1 3.26 3.26 0.07ns

Error 10 454.81 45.48 Total 11 458.07

S) Non-dipt. Treatment 1 80.09 80.09 2.25ns

Error 10 317.83 31.78 Total 11 397.92

3. Sudecor

A) Dipterocarp Treatment 1 527.19 527.19 9.24** Error 10 571.26 57.13 Total 11 1,099.14

S) Non-dipt. Treatment 315.19 315.19 1.68ns

Error 10 1,877.16 187.72 Total 11 2,192.35

4. GPTOC

A) Dipterocarp Treatment 231.88 231.88 3.76ns

Error 10 615.80 61.58 Total 11 847.68

S) Non-dipt. Treatment 1 268.38 268.38 11.05** Error 10 242.76 24.28 Total 11 511.14

* significant at 0.05

** significant at 0.01 ns not significant

37

Appendix Table 11. Analysis of variance of initial and final (after ten years) basal area per hectare among TSI sites.

SV DF SS MS F

I. At establishment

A) Dipterocarp Treatment I 0.50 0.50 O.Olns

Error 6 391.60 65.27 Total 7 392.10

B) Non-dipterocarp Treatment 89.70 89.70 2.67ns

Error 6 134.30 33.58 Total 7 224.00

11. After ten years

A) Dipterocarp Treatment 1 1,018.14 1,018.14 0.45ns

Error 6 13,652.60 2,275.43 Total 7 14,670.74

B) Non-dipterocarp Treatment 3,209.59 3,209.59 1.48ns

Error 6 12,997.40 2,166.23 Total 7 16,206.99

ns not significant

Appendix Table 12. Analysis of variance of initial and final (after ten years) volume per hectare among TSI study sites.

• SV DF SS MS F

I. At establishment

A) Dipterocarp Treatment 9.29 9.29 0.004ns

Error 6 14,801.17 2,466.86 Total 7 14,810.46

B) Non-dipterocarp Treatment 1 3,936.94 3,936.94 1.39ns

Error 6 16,974.64 2,829.11 Total 7 20,911.58

11. After ten years

A) Dipterocarp Treatment 1 5,382.03 5,382.03 0.02ns

Error 6 1,403,386.94 233,897.82 Total 7 1,408,768.97

B) Non-dipterocarp Treatment 157,599.82 157,599.82 0.81ns

Error 6 1,169,231.24 194,871.97 Total 7 1,326,831.06

ns not significant

38

Appendix Table 11. Analysis of variance of initial and final (after ten years) basal area per hectare among TSI sites.

SV DF SS MS F

I. At establishment

A) Dipterocarp Treatment I 0.50 0.50 O.Olns

Error 6 391.60 65.27 Total 7 392.10

B) Non-dipterocarp Treatment 89.70 89.70 2.67ns

Error 6 134.30 33.58 Total 7 224.00

11. After ten years

A) Dipterocarp Treatment 1 1,018.14 1,018.14 0.45ns

Error 6 13,652.60 2,275.43 Total 7 14,670.74

B) Non-dipterocarp Treatment 3,209.59 3,209.59 1.48ns

Error 6 12,997.40 2,166.23 Total 7 16,206.99

ns not significant

Appendix Table 12. Analysis of variance of initial and final (after ten years) volume per hectare among TSI study sites.

• SV DF SS MS F

I. At establishment

A) Dipterocarp Treatment 9.29 9.29 0.004ns

Error 6 14,801.17 2,466.86 Total 7 14,810.46

B) Non-dipterocarp Treatment 1 3,936.94 3,936.94 1.39ns

Error 6 16,974.64 2,829.11 Total 7 20,911.58

11. After ten years

A) Dipterocarp Treatment 1 5,382.03 5,382.03 0.02ns

Error 6 1,403,386.94 233,897.82 Total 7 1,408,768.97

B) Non-dipterocarp Treatment 157,599.82 157,599.82 0.81ns

Error 6 1,169,231.24 194,871.97 Total 7 1,326,831.06

ns not significant

38

Appendix Table 13. Analysis of variance of initial volume per hectare in each TSI study site.

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 214.60 214.60 0.04ns

Error 10 50,661.90 5,066.20 Total 11 50,876.50

S) Non-dipt. Treatment 1 1.33 1.33 0.002ns

Error 10 6,403.90 640.39 Total 11 6,405.23

2. Acoje

A) Dipterocarp Treatment 3,614.00 3,614.00 0.55ns

Error 10 65,682.30 6,568.23 Total 11 69,296.30

S) Non-dipt. Treatment 1 8,138.02 8,138.02 1.80ns

Error 10 45,272.90 4,527.27 Total 11 53,410.92

3. Sudecor

A) Dipterocarp Treatment 1 6.38 6.38 0.001 ns

Error 10 81,444.77 8,144.48 Total 11 81,451.15

S) Non-dipt. Treatment 1 33,867.20 33,867.20 4.59ns

Error 10 73,795.96 7,379.56 Total 11 107,662.80

4. GPTOC

A) Dipterocarp Treatment 1 3,870.02 3,870.02 0.42ns

Error 10 91,975.96 9,197.59 Total 11 95,845.98

S) Non-dipt. Treatment 1,022.13 1,022.13 0.25ns

Error 10 40,357.38 4,035.74 Total 11 41,379.51

* significant at 0.05 ns not significant

39

, , " < : .~ .: ; .. "::" >. ~-~"':': :'~ ':', '. ':"~-.-:" ':'~", ".~:.;~~r?~ '. :",-': :, . '. " " :,-.~ :.;,;"", : ,-, " " .•. ;': :' .: '" .• ~ ":.' . " ~:,;:.~ ":.,.~".~ _~ ~"~:::::'::-L"'-"": ''''.":- ':. " ': .. - ...... .:::. ," '.'~:" : ~.:.",., ".~ .:" ~ ! ".";- •. ' '. -::::;~.-•.• -, '-'':·""-::::''''":'"If'''''_·~ .. '''7 .. -· .. -'''''',-; • "~.:: '. - ..

Appendix Table 13. Analysis of variance of initial volume per hectare in each TSI study site.

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 214.60 214.60 0.04ns

Error 10 50,661.90 5,066.20 Total 11 50,876.50

S) Non-dipt. Treatment 1 1.33 1.33 0.002ns

Error 10 6,403.90 640.39 Total 11 6,405.23

2. Acoje

A) Dipterocarp Treatment 3,614.00 3,614.00 0.55ns

Error 10 65,682.30 6,568.23 Total 11 69,296.30

S) Non-dipt. Treatment 1 8,138.02 8,138.02 1.80ns

Error 10 45,272.90 4,527.27 Total 11 53,410.92

3. Sudecor

A) Dipterocarp Treatment 1 6.38 6.38 0.001 ns

Error 10 81,444.77 8,144.48 Total 11 81,451.15

S) Non-dipt. Treatment 1 33,867.20 33,867.20 4.59ns

Error 10 73,795.96 7,379.56 Total 11 107,662.80

4. GPTOC

A) Dipterocarp Treatment 1 3,870.02 3,870.02 0.42ns

Error 10 91,975.96 9,197.59 Total 11 95,845.98

S) Non-dipt. Treatment 1,022.13 1,022.13 0.25ns

Error 10 40,357.38 4,035.74 Total 11 41,379.51

* significant at 0.05 ns not significant

39

Appendix Table 14. Analysis of variance of average volume per hectare in each TSI study site after ten years.

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 3,897.01 3,897.01 0.42ns

Error 10 92,212.26 9,221.23 Total 11 96,109.27

B) Non-dipt. Treatment 28.52 28.52 0.03ns

Error 10 10,892.40 1,089.84 Total 11 10,926.92

2. Acoje

A) Dipterocarp Treatment 3,631.38 3,631.38 0.49ns

Error 10 73,993.92 7,399.39 Total 11 77,625.30

B) Non-dipt. Treatment 6,912.00 6,912.00 1.35ns

Error 10 51,269.88 5,126.99 Total 11 58,181.88

3. Sudecor

A) Dipterocarp Treatment 17,825.52 17,825.52 0.97ns

Error 10 184,025.71 18,402.57 Total 11 201,851.23

B) Non-dipt. Treatment 1 33,522.76 33,522.76 2.12ns

Error 10 157,699.30 15,769.93 Total 11 191,222.06

4. GPTOC

A) Dipterocarp Treatment 1 2,408.33 2,408.33 2.12ns

Error 10 11,349.23 1,134.92 Total 11 13,757.56

B) Non-dipt. Treatment 2,715.02 2,715.02 3.66ns

Error 10 7,424.53 742.45 Total 11 10,139.55

* significant at 0.05 ns not significant

40

Appendix Table 14. Analysis of variance of average volume per hectare in each TSI study site after ten years.

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 3,897.01 3,897.01 0.42ns

Error 10 92,212.26 9,221.23 Total 11 96,109.27

B) Non-dipt. Treatment 28.52 28.52 0.03ns

Error 10 10,892.40 1,089.84 Total 11 10,926.92

2. Acoje

A) Dipterocarp Treatment 3,631.38 3,631.38 0.49ns

Error 10 73,993.92 7,399.39 Total 11 77,625.30

B) Non-dipt. Treatment 6,912.00 6,912.00 1.35ns

Error 10 51,269.88 5,126.99 Total 11 58,181.88

3. Sudecor

A) Dipterocarp Treatment 17,825.52 17,825.52 0.97ns

Error 10 184,025.71 18,402.57 Total 11 201,851.23

B) Non-dipt. Treatment 1 33,522.76 33,522.76 2.12ns

Error 10 157,699.30 15,769.93 Total 11 191,222.06

4. GPTOC

A) Dipterocarp Treatment 1 2,408.33 2,408.33 2.12ns

Error 10 11,349.23 1,134.92 Total 11 13,757.56

B) Non-dipt. Treatment 2,715.02 2,715.02 3.66ns

Error 10 7,424.53 742.45 Total 11 10,139.55

* significant at 0.05 ns not significant

40

Appendix Table 15. Analysis of variance of average basal area increment in each site.

SV DF SS MS F

I. Taggat Treatment 0.009 0.009 4.50ns

Error 10 0.018 0.002 Total 11 0.027

2. Acoje Treatment 0.007 0.007 3.50ns

Error 10 0.016 0.002 Total 11 0.023

3. Sudecor Treatment 0.045 0.045 15.00** Error 10 0.026 0.003 Total 11 0.071

4. GPTDC Treatment 1 0.002 0.002 2.00ns Error 10 0.01 0.001 Total 11 0.012

* * significant at 0.01 ns not significant

Appendix Table 16. Analysis ofvariances of average volume increment in each site

SV OF SS MS F

1 . Taggat Treatment 1 0.45 0.45 1.45ns

Error 10 3.10 0.31 Total 11 3.55

2. Acoje Treatment 1 0.24 0.24 1.00ns

Error 10 2.41 0.24 Total 11 2.65

3. Sudecor Treatment 1 0.48 0.48 1.85ns

Error .10 2.59 0.26 Total 11

4. GPTDC Treatment 0.10 0.10 0.33ns

Error 10 3.03 0.30 Total 11 3.13

ns not significant

41

,-:>.":p:::. '-~ ~~.' ~'.~:'--:--~"'" . . - .. ~ .. " .. .:-. ~'. • ,_ ...... _ •• -" • _.' ~ ~.- w',' • ,. :i~";-:~~-"-• .1 _ .. 9·r·· .. ...-"··.,·~~~ __ y_~"...._·~· __ _

Appendix Table 15. Analysis of variance of average basal area increment in each site.

SV DF SS MS F

I. Taggat Treatment 0.009 0.009 4.50ns

Error 10 0.018 0.002 Total 11 0.027

2. Acoje Treatment 0.007 0.007 3.50ns

Error 10 0.016 0.002 Total 11 0.023

3. Sudecor Treatment 0.045 0.045 15.00** Error 10 0.026 0.003 Total 11 0.071

4. GPTDC Treatment 1 0.002 0.002 2.00ns Error 10 0.01 0.001 Total 11 0.012

* * significant at 0.01 ns not significant

Appendix Table 16. Analysis ofvariances of average volume increment in each site

•

SV OF SS MS F

1 . Taggat Treatment 1 0.45 0.45 1.45ns

Error 10 3.10 0.31 Total 11 3.55

2. Acoje Treatment 1 0.24 0.24 1.00ns

Error 10 2.41 0.24 Total 11 2.65

3. Sudecor Treatment 1 0.48 0.48 1.85ns

Error .10 2.59 0.26 Total 11

4. GPTDC Treatment 0.10 0.10 0.33ns

Error 10 3.03 0.30 Total 11 3.13

ns not significant

41

Appendix Table 17. Analysis of variance of average number of dead trees per hectare (mortality rate) in each TSI study site after ten years.

SV DF : SS MS F

1. Taggat

A) Dipterocarp Treatment 87,552.09 87,552.09 3.14ns

Error 10 279,270.83 27,927.08 Total 11 366,822.92

B) Non-dipt. Treatment 1 32,552.09 32,552.09 6.14* Error 10 53,020.83 5,302.08 Total 11 85,572.92

2. Acoje

A) Dipterocarp Treatment 1 3,333.34 3,333.34 4.32ns

Error 10 7,708.33 770.83 Total 11 11,041.67

B) Non-dipt. Treatment .. 1 349,947.91 349,947.91 29.62** Error 10 118,124.99 11,812.50 Total 11 468,072.90

3. Sudecor

A) Dipterocarp Treatment 208.34 208.34 0.06ns

Error 10 35,833.33 3,583.33 Total 11 36,041.67

B) Non-dipt. Treatment 1 181,302.08 181,302.08 15.13** Error 10 119,854.17 11,985.42 Total 11 301,156.25

4. GPTDC

A) Dipterocarp Treatment 1 13,333.34 13,333.34 3.54ns

Error 10 37,708.33 3,770.83 Total 11 51,041.67

B) Non-dipt. Treatment 60,208.34 60,208.34 5.50* Error 10 109,469.70 10,946.97 Total 11 169,678.04

* significant at 0.05 * * significant at 0.01 ns not significant

42

Appendix Table 17. Analysis of variance of average number of dead trees per hectare (mortality rate) in each TSI study site after ten years.

SV DF : SS MS F

1. Taggat

A) Dipterocarp Treatment 87,552.09 87,552.09 3.14ns

Error 10 279,270.83 27,927.08 Total 11 366,822.92

B) Non-dipt. Treatment 1 32,552.09 32,552.09 6.14* Error 10 53,020.83 5,302.08 Total 11 85,572.92

2. Acoje

A) Dipterocarp Treatment 1 3,333.34 3,333.34 4.32ns

Error 10 7,708.33 770.83 Total 11 11,041.67

B) Non-dipt. Treatment .. 1 349,947.91 349,947.91 29.62** Error 10 118,124.99 11,812.50 Total 11 468,072.90

3. Sudecor

A) Dipterocarp Treatment 208.34 208.34 0.06ns

Error 10 35,833.33 3,583.33 Total 11 36,041.67

B) Non-dipt. Treatment 1 181,302.08 181,302.08 15.13** Error 10 119,854.17 11,985.42 Total 11 301,156.25

4. GPTDC

A) Dipterocarp Treatment 1 13,333.34 13,333.34 3.54ns

Error 10 37,708.33 3,770.83 Total 11 51,041.67

B) Non-dipt. Treatment 60,208.34 60,208.34 5.50* Error 10 109,469.70 10,946.97 Total 11 169,678.04

* significant at 0.05 * * significant at 0.01 ns not significant

42

Appendix Table 18. Analysis of variance of average number of recruits per hectare (ingrowth rate) in each TSI study site after ten years.

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 5,208.33 5,208.33 1.58ns

Error 10 32,916.67 3,291.67 Total 11 38,125.00

B) Non-dipt. Treatment 208.33 208.33 0.04ns

Error 10 46,041.67 4,604.17 Total 11 46,250.00

2. Acoje

A) Dipterocarp Treatment 5,208.33 5,208.33 3.38ns

Error 10 15,416.67 1,541.67 Total 11 20,625.00

B) Non-dipt. Treatment 53,333.34 53,333.34 1.62ns

Error 10 330,208.33 33,020.83 Total. 11 383,533.67

3. Sudecor

A) Dipterocarp Treatment 1 155,468.75 155,468.75 5.41 * • Error 10 287,604.17 28,760.42 Total 11 443,072.92

B) Non-dipt. Treatment 181,302.08 181,302.08 3.62ns

Error 10 500,104.17 50,010.42 Total 11 681,406.25

4. GPTOC

A) Dipterocarp Treatment 40,833.33 40,833.33 5.90* Error 10 69,166.67 6,916.67 Total 11 110,000.00

B) Non-dipt. Treatment 4,218.75 4,218.75 0.51ns

Error 10 -83,437.50 8,343.75 Total 11 87,656.25

* significant at 0.05 ns not significant

43

.. .. .~-<:.::.~ .;,.,:.~~ ;_' >. ~.~ .. :-~:!. :.:~~~ :"~.';'~ .. :. ~.:>': '.. ~.~:''':'': ':.'~' <:~: .~ :":-";',: >: :~:; .. ~y .. ~.:. ~'.: ... '~--::'~ : ... : <':'.~ : ..... :.~ , .. ~F ........ ' .. :...... .: -.:_~: :-:' ':: ',-',: '<:" .: .. :-.;-:-.. - • ~~~'. > ... _ .... : ... :.:- ;--.'. : ... ~ :.:-" .: . ., .... ,'.', ... ~:.~~ ~ .... '.. : ";'/:'~

Appendix Table 18. Analysis of variance of average number of recruits per hectare (ingrowth rate) in each TSI study site after ten years.

SV OF : SS MS F

1. Taggat

A) Dipterocarp Treatment 5,208.33 5,208.33 1.58ns

Error 10 32,916.67 3,291.67 Total 11 38,125.00

B) Non-dipt. Treatment 208.33 208.33 0.04ns

Error 10 46,041.67 4,604.17 Total 11 46,250.00

2. Acoje

A) Dipterocarp Treatment 5,208.33 5,208.33 3.38ns

Error 10 15,416.67 1,541.67 Total 11 20,625.00

B) Non-dipt. Treatment 53,333.34 53,333.34 1.62ns

Error 10 330,208.33 33,020.83 Total. 11 383,533.67

3. Sudecor

A) Dipterocarp Treatment 1 155,468.75 155,468.75 5.41 * • Error 10 287,604.17 28,760.42 Total 11 443,072.92

B) Non-dipt. Treatment 181,302.08 181,302.08 3.62ns

Error 10 500,104.17 50,010.42 Total 11 681,406.25

4. GPTOC

A) Dipterocarp Treatment 40,833.33 40,833.33 5.90* Error 10 69,166.67 6,916.67 Total 11 110,000.00

B) Non-dipt. Treatment 4,218.75 4,218.75 0.51 ns

Error 10 -83,437.50 8,343.75 Total 11 87,656.25

* significant at 0.05 ns not significant

43

Appendix Table 19. Revenue and cost statements of TSI operations in the study areas.

TAGGAT ACOJE SUDECOR GPTDC ITEMS/SITE CC/age Amount CC/age Amount CC/age Amount CC/age

(years) (P) (years) (P) (years) (P) (years)

A. Revenue First TSI Trts. 17(0) 3,538.50 22(0) 2,167.20 13(0) 2,004.69 14(0) Second TSI Trts. 27(10) 479.13 32(10) 116.89 23(10) 89.19 24(10) Residual Stand 40(23) 1,181.40 45(23) 3,364.81 35(22) 4,547.26 40(26)

Total 5,199.03 5,648.90 6,641.14

B. Costs First TSI Trts. 17(0) 3,500.00 22(0) 3,500.00 13(0) 3,500.00 14(0) Second TSI Trts. 27(10) 566.34 32(10) 566.34 23(10) 566.34 24(10) Third TSI Trts. 40(20) 108.29 45(23) 108.29 35(20) 108.29 40(20)

Total 4,174.63 4,174.63 4,174.63

Where: CC = cutting cycle of residual dipterocarp stand (0) = year occurred at present time; first TSI treatments (10) = year occurred at second TSI operations, discounted to present time' (23) = remining years to reach the cutting cycle, discounted to present time

44

Amount (P)

3,614.52 226.76

2,378.21

6,219.49

3,500.00 566.34 108.29

4,174.63

..... : .. :~ .. ::).;<:~.~~:-:.<~~::.:{:.::~.:,~.:.::\(~?~~·F/\}::::::S: .. )S:··:·:::·:::::::·:::·:.~·:;::\\:(;>·:.:i:.h::··:~::'!;-;=;::·~;/:;\;;~:)[<.':;:/:~·:;·:··:.:·)/;::;;~:;:~::);:::\/Y('(·:·:~·:~·:f:~,?-?::::;>(\~~~

Appendix Table 19. Revenue and cost statements of TSI operations in the study areas.

TAGGAT ACOJE SUDECOR GPTDC ITEMS/SITE CC/age Amount CC/age Amount CC/age Amount CC/age

(years) (P) (years) (P) (years) (P) (years)

A. Revenue First TSI Trts. 17(0) 3,538.50 22(0) 2,167.20 13(0) 2,004.69 14(0) Second TSI Trts. 27(10) 479.13 32(10) 116.89 23(10) 89.19 24(10) Residual Stand 40(23) 1,181.40 45(23) 3,364.81 35(22) 4,547.26 40(26)

Total 5,199.03 5,648.90 6,641.14

B. Costs First TSI Trts. 17(0) 3,500.00 22(0) 3,500.00 13(0) 3,500.00 14(0) Second TSI Trts. 27(10) 566.34 32(10) 566.34 23(10) 566.34 24(10) Third TSI Trts. 40(20) 108.29 45(23) 108.29 35(20) 108.29 40(20)

Total 4,174.63 4,174.63 4,174.63

Where: CC = cutting cycle of residual dipterocarp stand (0) = year occurred at present time; first TSI treatments (10) = year occurred at second TSI operations, discounted to present time' (23) = remining years to reach the cutting cycle, discounted to present time

44

Amount (P)

3,614.52 226.76

2,378.21

6,219.49

3,500.00 566.34 108.29

4,174.63