Sustainable harvesting of medicinal bark: Experimental research and formulation of harvest prescriptions

Wessel Vermeulen Conservation Services South African National Parks Knysna

Coert Geldenhuys Department of Forest Science University of Stellenbosch Introduction (Mander 1998) •Some 27 million traditional medicine consumers in South • More than 100 000 practicing traditional healers using indigenous • The economic activity generated by traders and healers has a value of ca R270 million per annum • More than 700 species • The most valued traditional medicine comes from forest and woodlands • Medicinal tree bark important component 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. Summary of results (Botha 2001)

• Number of species • Common species traded and with highest turnover – Mpumalanga: 176 – Acacia xanthophloea – Limpopo: 70 – Acridocarpus • Almost 50% species natalitius – Capparis tomentosa are trees – Catha edulis • Mpumalanga: Bark – Croton megalobotrys – Cassine 23% of plant parts transvaalensis traded – Rapanea melanophloeos Uncontrolled bark harvesting PROCESS OF SUSTAINED YIELD DETERMINATION

Identify Defining stakeholders Product

Resource Delineation of inventory Resource Area

Population Recruitment and dynamics and Reproductive plant Phenology demography Development Monitoring Implementation of Harvest and Revision and System and (Adaptive Management Management Management) Control Prescriptions Key issues for sustainable bark harvesting

Response of different species to bark stripping • Bark regrowth – Extent –Rate • Susceptibility to: – Fungal attack – Insect damage Species selection (RSA, , ) Forest Woodland Cryptocarya myrtifolia Albizia adianthifolia Curtisia dentata Brachystegia bussei Ilex mitis B. spiciformis Ocotea bullata Dalbergia nitidula Prunus africana Elaeodendron transvaalense Rapanea melanophloeos paniculata Rhus chirindensis J. globiflora Zanthoxylum davyi Parinari curatellifolia Pseudolachnostylis maprouneifolia Pterocarpus angolensis Study area

Medium-moist High Forest

Groenkop

Witelsbos

Moist High Forest Treatments

• Removal of 1 m long strips • Different strip widths (5 – 15 cm) • Range of tree diameters • Winter and summer treatments Assessments

• Six month interval

• Bark regrowth – Edge growth – Sheet growth Edge Sheet • Damage through: – Fungal attack – Insect attack Edge growth • Recorded percentage of wound edge with edge growth (% classes) 0 = no edge growth 1 = 1 – 10% 2 = 11 – 20%, etc. • Rate of wound closure Edge growth (%)

P. africana 36 months 12 months

10

9 Winter Summer 8 e

7 g

12 6

5 10

4 8

3 6 Class average

2 avera Class 4

1 2

0 0 Ocot bull Rapa mela Curt dent Ilex miti Prun afri Rhus chir

Species Rate of wound closure

O. bullata

20 Winter Summer )

15 mm (

8

10 6

4 row rate th 5 2 g

e Ilex miti Prun afri Rhus chir 0 g

0 Ed -2 Growth rate (mm/annum) rate Growth

Ocot bull Rapa mela Curt dent -4

-5 -6

Species Sheet growth

• Recorded percentage of wound edge with edge growth (% classes) 0 = no sheet growth 1 = 1 – 10% 2 = 11 – 20%, etc. Sheet growth (%)

I. mitis 36 months 12 months

4 Winter 3.5 Summer

3 9

8 2.5 7

2 6

5 1.5

4 Class average 1 Class average Class 3

0.5 2

1 0

0 Ocot bull Rapa mela Curt dent Ilex miti Prun afri Rhus chir

Species Fungal growth

• Recorded percentage of wound edge with edge growth (% classes) 0 = no fungal growth 1 = 1 – 10% 2 = 11 – 20%, etc. Fungal growth (%)

36 months 12 months

2.5 Winter Summer e 2 g

5

4.5 1.5 4

3.5

3 1 2.5

2 Class average

1.5 0.5 avera Class 1

0.5

0 0

Ocot bull Rapa mela Curt dent Ilex miti Prun afri Rhus chir Species Insect attack

• Pinhole classes 1 = 1 – 2 2 = 3 – 5 3 = 6 – 10 4 = 11 – 20 5 = 21+ • Damage other than small pinholes also recorded Insect damage (pinhole classes)

36 months 12 months

3.5 Winter

3 Summer e g 2.5

1.8

1.6 2 1.4

1.2 1.5 1

0.8 1 Class average

0.6Class avera

0.4 0.5 0.2

0 0

Ocot bull Rapa mela Curt dent Ilex miti Prun afri Rhus chir Species

Consistent with % of trees with that suffered insect damage Tree response: Summary

• No wound closure • Wound closure through edge • Wound closure through sheet growth • Different rates of wound Rapanea Ocotea closure • Varying degrees of susceptibility to fungal and insect attack

Ilex Prunus Rapanea 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 Decision

tree Tree response to bark stripping: Wound closure

Group A Group B

Wound closure through sheet No wound closure and/or edge growth

Strip harvesting Full tree harvesting 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) Decision

tree Tree response to bark stripping: Wound closure

Group A Group B

Wound closure through sheet No wound closure and/or edge growth

Strip harvesting Full tree harvesting Decision Group A tree

Sheet Extent and rate of Edge growth growth wound closure

1 Slow 2 Fair 3 Good

Criteria Criteria Criteria <50% edge or sheet 50-75% >75% cover after one year Decision Group A tree Susceptibility to insect and fungal attack

1 Major 2 Minor 3 None or negligible

Criteria Criteria Criteria Pinhole class average Pinhole class average Pinhole class average >3 after one year 1 - 3 <1 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 Selection of harvest system

Insect and Fungal attack

1 Major 2 Minor 3 None Wound None Full tree Full tree Full tree closure harvesting harvesting harvesting 1 Slow Full tree Full tree Strip harvesting harvesting harvesting 2 Fair Full tree Strip Strip harvesting harvesting harvesting 3 Good Strip Strip Strip harvesting harvesting harvesting Selection of harvest system

Insect and Fungal attack

1 Major 2 Minor 3 None

Wound None Full tree Full tree Full tree closure harvesting harvesting harvesting 1 Slow Full tree Full tree Strip harvesting harvesting harvesting 2 Fair Full tree Strip Strip harvesting harvesting harvesting 3 Good Strip Strip Strip harvesting harvesting harvesting Buffer zone species

Factors to be taken into consideration with final allocation to harvest system

Bark lift Agony shoots Excretions Other damage Allocation of species: Southern Cape Forest Insect and/or Fungal damage

1 Major 2 Minor 3 None

Wound None Rapanea FULL-TREE closure melanophloeos HARVESTING 1 Slow Rhus BUFFER ZONE chirindensis

2 Fair Curtisia dentata Ilex mitis

3 Good STRIP Ocotea bullata HARVESTING Prunus africana Harvest prescriptions for strip harvesting • Strip width • Harvest season • Strip length • Tree diameter • Harvest rotation • Percentage of • Number of strips growing stock • Side of tree • Harvest method

No fixed way of formulating prescriptions 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 Harvest prescriptions: Strip width (edge growth), harvest percent and rotation

Insect and/or Fungal damage

1 Major 2 Minor 3 None Wound None FULL TREE closure HARVESTING 1 Slow 5cm strip 33% of stock 2 Fair 5cm strip 10 cm strip 33% of stock 50% of stock 3 Good 5cm strip 10 cm strip 10 cm strip 33% of stock 50% of stock 66% of stock

! Harvest rotation should allow for wound closure ! Strip width for sheet growth could be proportional to tree diameter 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 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) Ocotea bullata – Coppice growth • 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) Rapanea melanophloeos - • In consultation with stakeholders Regeneration Response of woodland species

Brachystegia spp. Woodland species

Pseudolachnostylis maprouneifolia

Pterocarpus angolensis

Parinari curatellifolia Dalbergia nitidula Woodland species (Syampungani 2005) Species Bark recovery Albizia adianthifolia Very good Julbernardia paniculata Good Pseudolachnostylis maprouneifolia Good Pterocarpus angolensis Good Dalbergia nitidula Good (M) / Poor (Z) Parinari curatellifolia Poor (M) / Good (Z) Brachystegia bussei Poor B. spiciformis Very poor (M) / Good (Z) Elaeodendron transvaalense None J. globiflora None 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) Acknowledgements

• UK Department for International Development – Forestry Research Programme • Innovation Fund - Commercial Products from the Wild • Field assistants: Jeffrey Sass & Daniel James