ACP-EU FORENET Research Workshop 18th -19th Dec, Montpellier

Mixed species volume equation for lowland tropical forests.

F. Oavika, PNGFRI

Introduction.

Local tree volume equations as well as biomass allometric equations are

important requirements for MRV under UN REDD guidelines.

The use of volume equation for estimation of forest timber volume is

necessary for MRV (monitoring, reporting & verification) purposes. It is

required to have a basis for a volume calculation based on local

information. It is also useful to have information available for

development of volume tables for use within the country.

Tree volume assessment was also taken as part of the biomass

measurement for the development of allometric equations in the

implementation of the Cross continental project in the ACP countries.

Trees felled for biomass assessment were first assessed for volume.

Project site

Oomsis

SITE FOR CROSS CONTINENTAL PROJECT: OOMSIS FOREST AREA

Lae

area vegetation type – medium crowned forest-(PNGRIS)

Oomsis forest area

natural lowland mixed species forest – Oomsis Blk 2b 350 ha

Main species: Anisoptera, Pometia, Planchonella, Canarium, Celtis,

Tree volume assessment • Volume assessment was done by destructive sampling of

trees for biomass.

• Using sectional measurements.

– Total stem was divided into 2m sections

– Diameters were taken at midpoints of these sections.

– Volume was calculated using Huber formula for each section. V = π.d2.L d = mid diam, L=section len

– Total volume overbark (vob)was the sum total of the sectional measurements.

spp dbh Vob

4 pom pin 52.8 2.900771

5 pom pin 22.2 0.525306

8 pom pin 41 1.8906

9 pom pin 25.9 0.452498

10 pom pin 37.3 1.03322

4 cry spp 38.2 1.549972

1 cry spp 51.5 2.917149

2 cry spp 30.3 0.898101

7 pom pin 55.7 3.570668

1 Pla spp 15.1 0.161632

2 Hap spp 18.6 0.236541

3 Hap spp 19.6 0.25201

7 Hap spp 40.6 1.332924

5 Lit spp 38.3 1.104621

3 Can spp 18.2 0.235698

6 Can spp 20.6 0.35078

3 Ani thu 44.3 2.768877

9 Ani thu 16.1 0.155903

10 Ani thu 28.7 0.695389

11 Ani thu 73.3 5.59245

13 Ani thu 52.9 3.599671

VOB above buttress for 7 species

y = 0.0002x2.3896 R² = 0.9780

0

1

2

3

4

5

6

7

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0

Vo

um

e o

ver

bar

k (m

3)

Diameter (cm)

dbh vs vob

dbh vs vob

The relationship can be fitted by a power model y = abc

Over estimation of volume

When there is greater differences between the log ends, the volume may be

overestimated.

Scaling manual – smalian’s formula, ministry of forests, Lands and NRO, 2011

DBH BL ML SendDiam HL diff

44.3 32.68 19.7 8.8 32.24 0.44

73.3 35.20 19.3 14.7 34.6 0.6

18.2 16.50 12.1 8.6 16.25 0.25

20.6 17.80 8.07 8.8 16.9 0.9

38.2 25.76 11.29 16.8 25.88 -0.12

51.5 30.80 15 9.1 30.4 0.4

30.3 24.20 15.36 4.9 24.1 0.1

49.7 26.77 8.84 11.9 26.35 0.42

29.5 21.94 12.79 14.9 20.97 0.97

22.8 21.25 10.37 5.1 20.65 0.6

31.4 25.97 12.2 6.3 25.95 0.02

20.1 18.10 10.5 8.5 18.05 0.05

15.1 19.25 12.83 1.9 18.63 0.62

24.4 27.43 19.1 3.2 27.71 -0.28

42.2 34.85 28 13 34.47 0.38

14.3 18.20 11.8 4.6 18.1 0.1

31.6 28.12 26.8 3.2 28.06 0.06

25.5 24.40 21.05 6.8 24.2 0.2

22.2 24.31 7.51 7.4 24.15 0.16

55.7 27.85 13.75 19.2 26.9 0.95

Stem length & Horizontal length in relation to taper

Concluding remarks

The vob generally has a strong correlation with dbh and is usually explained by a

simple power function. The power model is also allometric in nature and can also

be linearised.

The volume equation should complement the biomass equations for estimating

volume of natural forest stands for REDD purposes.

Thank you

Merci beaucoup