sustainable harvesting of medicinal bark experimental research and
TRANSCRIPT
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Sustainable harvesting of medicinal bark: Experimental research and formulation of harvest prescriptions
Wessel VermeulenConservation ServicesSouth African National ParksKnysna
Coert GeldenhuysDepartment of Forest ScienceUniversity of Stellenbosch
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Introduction (Mander 1998)
• Some 27 million traditional medicine consumers in South Africa
• More than 100 000 practicing traditional healers using indigenous plants
• The economic activity generated by traders and healers has a value of ca R270 million per annum
• More than 700 plant species• The most valued traditional medicine comes
from forest and woodlands• Medicinal tree bark important component
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Kruger National Park• Botha, J. 2001. Perceptions of
species availability and values of medicinal plants traded in areas adjacent to Kruger National Park.MSc. Thesis, University of the Witwatersrand.
• Botha, J., Witkowski, E.T.F. & Chackleton, C.M. 2001. An inventory of medicinal plants traded on the western boundary of the Kruger National Park, South Africa. Koedoe 44(2): 7-46.
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Summary of results (Botha 2001)
• Number of species traded– Mpumalanga: 176– Limpopo: 70
• Almost 50% species are trees
• Mpumalanga: Bark 23% of plant parts traded
• Common species and with highest turnover– Acacia xanthophloea– Acridocarpus
natalitius– Capparis tomentosa– Catha edulis– Croton megalobotrys– Cassine
transvaalensis– Rapanea
melanophloeos
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Uncontrolled bark harvesting
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Defining Product
Resource inventory
Population dynamics and plant demography
Identify stakeholders
Delineation of Resource Area
Recruitment and Reproductive Phenology
Development of Harvest System and Management Prescriptions
Monitoring and Revision (Adaptive Management)
Implementation and Management Control
PROCESS OF SUSTAINED YIELD DETERMINATION
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Key issues for sustainable bark harvestingResponse of different species to bark
stripping• Bark regrowth
– Extent– Rate
• Susceptibility to:– Fungal attack– Insect damage
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Species selection (RSA, Malawi, Zambia)
Albizia adianthifoliaBrachystegia busseiB. spiciformisDalbergia nitidulaElaeodendron transvaalenseJulbernardia paniculataJ. globifloraParinari curatellifoliaPseudolachnostylismaprouneifoliaPterocarpus angolensis
Cryptocarya myrtifoliaCurtisia dentataIlex mitisOcotea bullataPrunus africanaRapanea melanophloeosRhus chirindensisZanthoxylum davyi
WoodlandForest
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Study area
Groenkop
Witelsbos
Medium-moist High Forest
Moist High Forest
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Treatments
• Removal of 1 m long strips
• Different strip widths (5 – 15 cm)
• Range of tree diameters
• Winter and summertreatments
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Assessments
• Six month interval
• Bark regrowth– Edge growth– Sheet growth
• Damage through:– Fungal attack– Insect attack
SheetEdge
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Edge growth• Recorded
percentage of wound edge with edge growth (% classes)0 = no edge growth1 = 1 – 10%2 = 11 – 20%, etc.
• Rate of wound closure
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Edge growth (%)
0
2
4
6
8
10
12
Ilex miti Prun afri Rhus chir
Species
Cla
ss a
vera
ge
0
1
2
3
4
5
6
7
8
9
10
Ocot bull Rapa mela Curt dent
Cla
ss a
vera
ge
WinterSummer
36 months 12 monthsP. africana
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Rate of wound closure
-6
-4
-2
0
2
4
6
8
Ilex miti Prun afri Rhus chir
Species
Edge
gro
wth
rate
(mm
)
-5
0
5
10
15
20
Ocot bull Rapa mela Curt dent
Gro
wth
rat
e (m
m/a
nnum
)
WinterSummer
O. bullata
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Sheet growth
• Recorded percentage of wound edge with edge growth (% classes)0 = no sheet growth1 = 1 – 10%2 = 11 – 20%, etc.
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Sheet growth (%)
0
1
2
3
4
5
6
7
8
9
Ilex miti Prun afri Rhus chir
Species
Cla
ss a
vera
ge
I. mitis
0
0.5
1
1.5
2
2.5
3
3.5
4
Ocot bull Rapa mela Curt dent
Cla
ss a
vera
ge
WinterSummer
36 months 12 months
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Fungal growth
• Recorded percentage of wound edge with edge growth (% classes)0 = no fungal growth1 = 1 – 10%2 = 11 – 20%, etc.
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Fungal growth (%)
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Ilex miti Prun afri Rhus chirSpecies
Cla
ss a
vera
ge
0
0.5
1
1.5
2
2.5
Ocot bull Rapa mela Curt dent
Cla
ss a
vera
ge
WinterSummer
36 months 12 months
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Insect attack• Pinhole classes
1 = 1 – 22 = 3 – 53 = 6 – 104 = 11 – 205 = 21+
• Damage other than small pinholes also recorded
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Insect damage (pinhole classes)
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
Ilex miti Prun afri Rhus chirSpecies
Cla
ss a
vera
ge
Consistent with % of trees with that suffered insect damage
0
0.5
1
1.5
2
2.5
3
3.5
Ocot bull Rapa mela Curt dent
Cla
ss a
vera
ge
WinterSummer
36 months 12 months
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Tree response: Summary• No wound closure• Wound closure through
edge• Wound closure through
sheet growth• Different rates of wound
closure• Varying degrees of
susceptibility to fungal and insect attack
Rapanea Ocotea
Ilex PrunusRapanea
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Approach with development of harvest system• Group species together based on
their response to bark stripping• Develop harvest prescriptions for
species groups
• Objective way• Decision tree
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Decision tree Tree response to
bark stripping: Wound
closure
Wound closure
through sheetand/or edge
growth
No wound closure
Strip harvesting Full tree harvesting
Group A Group B
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Full tree harvesting• Sustainable felling of trees for
bark harvesting• Harvesting of bark from stem
and branches• Could also be applied to
species identified for strip harvesting, especially commercial bark harvesting
• Timber yield regulation system– Growing stock inventory– Rate of turnover (ingrowth and
mortality)
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Decision tree Tree response to
bark stripping: Wound
closure
Wound closure
through sheetand/or edge
growth
No wound closure
Strip harvesting Full tree harvesting
Group A Group B
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Decision tree
Extent and rate ofwound closure
1 Slow 3 Good
<50% edge or sheetcover after one year
>75%
2 Fair
Edgegrowth
Sheetgrowth
50-75%
Group A
Criteria Criteria Criteria
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Decision tree
Susceptibility toinsect and fungal
attack
1 Major 3 None ornegligible
Pinhole class average>3 after one year
Pinhole class average <1
2 Minor
Pinhole class average1 - 3
Group A
CriteriaCriteriaCriteria
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Development of harvest system
Consider both– the rate of wound closure and– susceptibility to insect and fungal
attack in the selection of a harvest system
Practical to apply
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Selection of harvest system
Strip harvesting
Strip harvesting
Strip harvesting
3 Good
Strip harvesting
Strip harvesting
Full tree harvesting
2 Fair
Strip harvesting
Full tree harvesting
Full tree harvesting
1 Slow
Full tree harvesting
Full tree harvesting
Full tree harvesting
NoneWound closure
3 None2 Minor1 Major
Insect and Fungal attack
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Selection of harvest system
Strip harvesting
Strip harvesting
Strip harvesting
3 Good
Strip harvesting
Strip harvesting
Full tree harvesting
2 Fair
Strip harvesting
Full tree harvesting
Full tree harvesting
1 Slow
Full tree harvesting
Full tree harvesting
Full tree harvesting
NoneWound closure
3 None2 Minor1 Major
Insect and Fungal attack
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Buffer zone speciesFactors to be taken into consideration with final allocation to harvest system
Bark liftAgony shoots
ExcretionsOther damage
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Allocation of species: Southern Cape Forest
Ocotea bullataPrunus africana
STRIP HARVESTING
3 Good
Curtisia dentataIlex mitis
2 Fair
BUFFER ZONERhus chirindensis
1 Slow
FULL-TREE HARVESTING
Rapanea melanophloeos
NoneWound closure
3 None2 Minor1 Major
Insect and/or Fungal damage
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Harvest prescriptions for strip harvesting
• Strip width• Strip length• Harvest rotation• Number of strips• Side of tree
• Harvest season• Tree diameter• Percentage of
growing stock• Harvest method
No fixed way of formulating prescriptions
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Harvest rotation and strip width• Rotation should allow for wound
closure• Trade-off
– The wider the strip width, the longer the harvest rotation and vice versa
– Major insect/fungal damage: Short rotation
• Indigenous knowledge
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Harvest prescriptions: Strip width (edge growth), harvest percent and rotation
10 cm strip66% of stock
10 cm strip50% of stock
5cm strip33% of stock
3 Good
Wound closure
! Harvest rotation should allow for wound closure! Strip width for sheet growth could be proportional to tree diameter
10 cm strip50% of stock
5cm strip33% of stock
2 Fair
5cm strip33% of stock
1 Slow
FULL TREE HARVESTING
None
3 None2 Minor1 Major
Insect and/or Fungal damage
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Monitoring and revision
• Long-term impact of bark harvesting on tree survival not yet known
• Monitoring of harvest impact and tree response to bark stripping
• Refine harvest prescriptions as part of an adaptive management approach
• For species for which no research results are available: use available knowledge
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Alternative resources / management options
• Coppice management (for species with active coppice regrowth)
• Establishment of forest stands for bark harvesting (on forest edge, in forest clearings)
• Cultivation for leaf harvesting(where active compounds are also present in the leaves)
• Integrated resources use (e.g. bark as by-product of timber harvesting)
• In consultation with stakeholders
Ocotea bullata –Coppice growth
Rapanea melanophloeos -Regeneration
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Response of woodland species
Brachystegia spp.
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Woodland species
Pterocarpusangolensis
Parinaricuratellifolia
Dalbergianitidula
Pseudolachnostylismaprouneifolia
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Woodland species (Syampungani 2005)
PoorBrachystegia bussei
Poor (M) / Good (Z)Parinari curatellifolia
Good (M) / Poor (Z)Dalbergia nitidula
GoodPterocarpus angolensis
GoodPseudolachnostylis maprouneifolia
GoodJulbernardia paniculata
NoneElaeodendron transvaalense
Very goodAlbizia adianthifolia
NoneJ. globiflora
Very poor (M) / Good (Z)B. spiciformis
Bark recoverySpecies
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Relevance to KNP• Unsustainable use has socio-
economic implications (apart from environmental)
• What happens outside the park could eventually also impact on achieving management objectives inside the park
• Kruger Park Traditional Healer’s Programme (1994)
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Acknowledgements• UK Department for International
Development – Forestry Research Programme
• Innovation Fund - Commercial Products from the Wild
• Field assistants: Jeffrey Sass & Daniel James