Rehabilitating the biodiversity and productivity of moist forests - - PowerPoint PPT Presentation

Rehabilitating the biodiversity and productivity of moist forests and deciduous woodlands through active resource use

Coert J. Geldenhuys

Forest and Wood Science, Stellenbosch University, Stellenbosch Plant and Soil Sciences, University of Pretoria, Pretoria cgelden@mweb.co.za

Capacity-development workshop for Central, Eastern and Southern Africa on the restoration of forests and other ecosystems to support the achievement of the AichiBiodiversity Targets, 2-6 October 2017, Durban, South Africa

What would be your thoughts about these situations?

Timber harvesting Fire Charcoal production Slash & burn Plant invasions Powerlines Road construction Mining Bark harvesting Residences

Is human resource use always bad? Or is conservation always good? What criteria do we use for objective assessment? I suggest that we have many wrong perceptions: Consider that: What looks good may be ecologically bad; Or, what looks bad may be ecologically very good! Every time I ask myself: Is this OK or bad? If it is BAD, how bad? Why? How does this relate to natural processes? Can it be restored?

• Uncontrolled resource use beyond recovery potential of

targeted species?

– Timber products - large-dimensions – Non-timber forest products – poles, fuel wood (charcoal & firewood), wood carving, etc – Non-wood forest products – bark for fiber and/or traditional medicine

• Changed fire regimes in fire-prone systems?

– Exclusion of fire – Cooler fires

• Alien plant invasions?

– Light-demanding versus shade-tolerant species

• Forest/woodland cleared for alternative uses?

– Crop cultivation - Food, bio-energy products, timber plantations, etc – Development of settlements, urban development, infrastructure, mining, etc

What are the causes of forest/woodland degradation?

• Major global concerns underlying need for cost-effective

approaches to rehabilitate natural forests/woodlands

– Degraded and cleared through

• slash-and-burn traditional agriculture
• charcoal production
• uncontrolled timber-harvesting practices with no silvicultural

management

• clearing for commercial agriculture, plantation forestry,

infrastructure development and mining – Alien plant invasions threaten biodiversity & ecological processes of natural vegetation systems, including natural forests – Climate change, Green-house gas emissions, etc

Why do we want to restore the specific landscape, ecosystem, species?

• Restore essential ecological processes

– Basis for maintaining optimum biological diversity – Adaptations to imposed stresses, disturbances, etc

• Restore their biological diversity per se

– Many floral and faunal components depend on forest ecosystem – Cannot be done without considering ecological processes at different levels

• Restore productive capacity

– for diverse resource use options of diverse resource users for diverse forest products

• Restore their environmental services

– nutrient cycling, carbon sequestration, soil and water conservation, etc

• Combination of ALL = Basic good forest management

Why do we want to restore the specific landscape, ecosystem, species?

When is a forest in degradation or in recovery?

FORESTS have INTEGRAL NATURAL DISTURBANCE & RECOVERY PROCESSES

• n the outside
• n the inside

Lightning without fire Lightning with fire Windfall gaps

Disturbances a natural part of all vegetation formations

• Biological components (species) of all forest/woodland types
• represent adaptations to different disturbance regimes
• form part of different (recovery) stages of vegetation
• they show different
• Growth/Life forms: trees, shrubs, herbs, etc.
• Bark types; Fruit & seed types
• Relative tolerances of forest/woodland species to
• Shade (pioneer vs early regrowth vs mature forest)
• Browsers (fire, fauna, people)

A disturbance is …..

• A discrete event (fire, browsing, tree fall,..) changing
• species & structure
• physiological processes
• resources: ± light, oC, nutrients
• Called a
• Non-event – frequency/impact too minor to cause response
• Incorporated – within adaptation & tolerance limits of entity; necessary

to maintain entity in current state

• Disaster – changes entity into new state; increases fitness
• Entity level: individual, population, community or landscape
• Human activities need to simulate natural disturbances to

which the forest/woodland system & its components are adapted

• Keep human resource use disturbances to level of Non-event &

Incorporated disturbance at level of population & community

• Focus rehabilitation at level of disaster to population, community, ...

Disturbances a natural part of all vegetation formations

• Total biodiversity of a particular vegetation system
• Depends on maintenance of different natural disturbance-recovery

processes in that vegetation

• If we totally protect a system, we loose important biodiversity

components of the system

• Action of disaster to one level may benefit
• Another level
• Eg breakdown of community structure (disaster) may benefit population of

pioneer/early regrowth species (eg Prunus)

• Another component at same level
• Eg lack of regeneration of pioneer species (disaster) may benefit

regeneration of more shade-tolerant species

• Greater disaster of disturbance at one level
• Longer period of recovery of that component/level towards original

condition of forest/woodland prior to disturbance event

Diversity in adaptations to disturbance

• Each forest has species adapted to different disturbance factors

at different regimes, mainly

• Shade tolerance in closed evergreen forests
• Fire tolerance in deciduous woodlands
• Other secondary factors = primary factors in some species
• Each species functions best under optimum conditions related

to primary factor of adaptation, in terms of

• Regeneration, establishment & productive growth
• = Main ecological criteria for sustainable functioning!
• Species dominance changes from early regrowth stands towards

mature forest

• In which stage do our target species show optimum development &

growth?

• What would be the best approach to rehabilitate specific

species/systems

A disturbance …

• may vary in its effect or impact, depending on
• its regime (intensity, frequency or area of impact)
• component species of system & their adaptations
• regime x habitat/site = landscape patterns

= Vegetation types & Biodiversity patterns

• forest-woodland-shrubland-grassland in same area

Forest/woodland formations in Africa

And how do they determine the composition & dynamics of the different systems, resource use practices, rehabilitation actions?

Everything we do causes changes – even doing nothing!

• Forest/Woodlands not museum pieces – DYNAMIC SYSTEMS!!
• How should we deal with Disturbance-Recovery processes in the

forest/woodland environment?

• Is it the inability of the vegetation to respond?
• OR is it our poor understanding [despite good intentions] of natural forest

& woodland dynamics?

• What multiple-use management systems will maintain natural

diversity when we use forest products & services?

• Can we rehabilitate natural complexities (species x age) in

degraded forests/woodlands?

Detailed forest location pattern with fire pathways: Storms River

Storms River bridge

Solid = fire burn, thickness = severity Broken = fire jump, up to 4 km

1 2

Plantations planted in fire pathway …. & regularly destroyed!

FOREST LOCATION PATTERN & PROCESS:

Forest location pattern determined by fires driven by prevailing winds (Bergwinds) in dry season: Forests persist in ‘fire-shadow’ areas in landscape

In South Africa, natural forests occur in areas with rainfall >725 mm/a in summer rainfall & >500 mm/a in winter/all year rainfall 7% of RSA has rainfall >800 mm/a; Forests cover only 0.1% Similar patterns can be seen in other parts of Africa Rehabilitating natural forest in the fire pathway will be fatal

• Fast-growing pioneer trees – often invasive alien species (eg Wattle)
• Buffer/nurse more variable & extreme conditions of regularly disturbed

grassland, shrubland & agricultural fields

• Facilitate establishment of shade-tolerant forest species
• Typical forest succession process

Stage 1: Stage 2: Stage 3: Stage 4: Dense pioneer stand Growing up & Further development/ Pioneer stand totally self-thinning thinning removed No understorey Sparse understorey Young regrowth forest Mixed regrowth forest Invader plant, or Invader plant or planted Forest trees and other Planted tree for woodlot tree removed species establishing timber, fruit, etc. for use or other purpose naturally or interplanted (thinning) (potentially traditionally used species)

Alien clearing action Rehabilitation action

AND we can manage the process, or benefit from it, at low cost!

Woody plants establish in landscape with disturbance (fire) exclusion

Pines Same happens with plantation stands on forest margin! AND with INVADER PLANT stands!! Eucalypts Acacias Keurboom (Virgilia divaricata) after fire

Our CONCEPT: Recovery of natural forest species follows a natural succession process towards diverse systems

• 2. Not Natural-

Forest Environment

• in fire zones

2.2 Non- forest, fire- adapted vegetation: Grassland, Shrubland, etc Follow traditional IAP clearing methods: cutting, herbicides, burning, etc Follow stand manipulation process as for natural forest environment (a) Development stage 1 1.1 Stands have NO utilization potential

Decision tree to decide on action in Invader plant stands in area with natural forest

• 1. Natural Forest

Environment

• in fire-shadow areas

Follow relevant stand manipulation guidelines for each stage to facilitate natural forest recovery 2.1 Naturalising Natural Forest: Area became non-fire landscape (in timber plantations or urban areas)

• 3. Conversion

to productive commercial land use (cropping, grazing, timber plantation, etc) Focus on integrated, cost- effective use of poles, timber, etc. & good forest recovery; Minimize damage to existing regeneration; if necessary, allow invasives to establish after cutting stand & manage recovery via stages 1 to 3 1.2 Stands have utilization potential (b) Development stages 2 & 3 (c) Development stage 4

Undisturbed forest Disturbed forest in different stages of recovery: Gabon Recovery is fast – by pioneer & early regrowth species – No need to plant mature forest species at high costs!

Slash & burn recovery in Tropical Moist Forest

Okoume 40 years after slash-&-burn Sep 2013 Aug 2015 Principe Island: Trema orientalis recovery 2 years after a fire

Limba (Terminalia superba): 80 cm DBH left, 50 cm DBH right - in Slash & Burn site after 50 years (Cameroon) Left: Okoume (Aucoumea klaineana) killed on edge of Slash & Burn site, Gabon – no value for farmer. Right: Okoume stand of 40 years developed from pioneer stand with Parasolier (Musanga cecropioides). Selective thinning of Okoume stands could be done by local farmers for benefits & forest recovery!

Examples from Cameroon, Gabon & Principe

Iroko / Amoreira (Melicia excelsa) a fast-growing pioneer tree in many parts of Africa and Sao Tome & Principe islands. Fastest-growing trees

• f 80 recorded trees grew >5 cm DBH per year

Natural Pioneer & Alien plantation/invader species can be your PARTNER in forest rehabilitation & biodiversity recovery!

• Use natural Pioneer/Alien process to reduce costs:
• provide rapid ground cover - prevent erosion
• add litter to degraded site - restore nutrient cycling
• provide shade to facilitate establishment of shade-tolerant natural

forest species – improve biodiversity recovery, no planting

• can provide rural resource use needs (fuel wood, poles, construction

material) - reduce pressure on natural forest; thinning

Stage 2 Stage 3 Stage 4 Stage 1

We need a changed mindset towards this cost-effective way to rehabilitate natural forest!

Miombo woodlands as main ecological system

Miombo Eco-region

• Seasonally dry with long dry season (4-6 months), with fires
• Adaptations to Browsing (fire, animals, people) as main disturbance factor
• Inherent low soil fertility
• Most tree species are light-demanding = develop even-aged stands

Dry (light green) & Wet (dark green) Miombo

Mozambique, Zimbabwe, South Africa (?), Malawi, Zambia, Angola, DR Congo, Tanzania Dominated by 3 genera: Brachystegia, Julbernadia, Isoberlinia

Closed woodland (forest) ↔ open woodland ↔ wooded grassland ↔ bushland & thicket = could be stand recovery stages

SUBSISTENCE:

• Daily domestic consumptive use
• Most rural, poor people
• From immediate vicinity of village

COMMERCIAL:

• Small, micro & medium enterprises (SMME’s)
• Fewer individuals, families & some communities
• Use resources & entrepreneurial skills
• Earn income beyond daily livelihood needs
• Industries, mainly export markets (using natural areas)
• Use specialized skills, technology & investment
• Timber industries (for construction, furniture and

plywood)

• Conversion of woodlands
• Crops (agriculture + tobacco, timber plantations),

livestock, infrastructure

• Conservation & Nature-based tourism (Parks)

Diverse products, values & services from woodlands

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Population pressure & Livelihood needs

• Commercial ventures over large areas

– Agriculture, forestry, mining, parks, urbanization, REDD+, etc

• Exploit resources for economic development elsewhere
• Reduce rural livelihood options

– Increase pressure on resources

Crops

Perception that this is area of Village But Village area is much larger Land for commercial land uses superimposed on Village areas – with severe consequences

Main direction of perceived degradation in Miombo woodland structure:

Open/closed mature woodland to scrub woodland Main factors in perceived degradation of woodland:

Clearing for growing crops; Collecting construction poles of different size; Collecting fuel wood (firewood & charcoal) for energy (cooking, etc)

HOWEVER, change is not in one direction, but cyclical: also from scrub woodland to open/closed mature woodland

Traditional landscape:

• Integrated agriculture, forestry,

settlements & conservation

• Maintain ecological processes,

diversity & productivity

Agriculture Conservation Mining Forestry

Commercial landscape:

• Segregated agriculture, forestry,

mining, urbanization & conservation

• Degrade ecological processes,

diversity & environmental health

What, and whose, criteria do we use to judge degradation & deforestation?

Government policies favor large-scale commercial ventures Many negative perceptions on Secondary forests, Slash & burn agriculture, Charcoal production, Clearing for crops - BUT, basis of livelihoods of millions

Browsing by fire, wildlife & people:

Main disturbance in Miombo woodland

Miombo species persist through vegetative regrowth from rootstocks & cut stems

Sprouting from rootstocks & damaged stems:

Main regeneration system in Miombo woodland

• Essential to clear mature

Miombo (not degradation

• r deforestation):
• Vegetative regrowth

needs light to grow fast

• Develop even-aged

stands with trees of uniform size

• Most diverse & productive

Slash-&-burn traditional agriculture & charcoal production

Cyclic clearing-cropping-fallow-regrowth maintains Miombo biodiversity & productivity

Moribund, old-growth stand & old, stunted seedlings on rootstock = 1 to >10 yrs old Active regrowth stand, even-aged, after slash- &-burn agriculture = 10 yrs old

• Extensive areas of secondary Miombo woodland:
• Light-demanding species growing fast from vegetative regrowth on

rootstocks/stumps to form even-aged stands

• = basis for sustainable resource use

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Mature woodland Advanced regrowth Advanced regrowth Young regrowth Earlier cleared Recently cleared and waiting to be burnt

Cyclic clearing = fast recovery of Miombo woodland: = NOT unidirectional loss

Very healthy, biodiverse & productive woodland: provide wide range of pole sizes, firewood, fiber & other uses for rural livelihoods

Regular disturbance maintains plant species diversity:

Most woodland species present from start of Miombo regrowth after Slash & Burn and Charcoal Production & persist on site (rootstocks)

Land use Total species recorded (woody & herbaceous Undisturbed woodland

50

Timber harvesting

64

Slash & burn agriculture

69

Charcoal production

74 What looks good (undisturbed woodland) = not necessarily ecologically good What looks bad (regular stand replacement) = ecologically good to rejuvenate Miombo woodland & species (best silviculture)

With perception

• f good
• r bad

Zambian study: Syampungani, S., Geldenhuys, C.J. & Chirwa, P.W. (2016). Regeneration dynamics of Miombo woodland in response to different anthropogenic disturbances: forest charaterisation for sustainable management. Agroforestry Systems

7yrs old regrowth stand

Woodland stands in development stages are even-aged: need stands in each age class for sustainable use

10 cm diameter in 7 years = 1.4 cm/yr in stem diameter growth: With NO silvicultural management

Regrowth is fast in secondary Miombo woodland

10 yr old regrowth stand Can we improve stand growth through silvicultural management? 30 yr old regrowth stand

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Silvicultural management in stand development stages

= key to better resource use management:

Selective thinning can provide laths THEN poles THEN timber

Stage 1 1–2m ht Stage 3 5–15m ht Stage 2 2–5m ht Stage 4 (mature) 12–25m ht

Selective thinning & pruning as part of normal harvesting of poles, firewood & fibers: women in stages 1-2, men in stage 3 Clearfell in groups (gaps): timber, charcoal & cropping

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Implement selective stem thinning and branch pruning:

Remove poor stems: form, defects, suppressed, etc; Provide growing space for good stems; Use material for poles of different size Annual resource use come from all development stages

to provide in pole & smaller dimension fuel wood needs; to improve growth of selected remaining stems

(free use of sunlight, carbon dioxide in atmosphere; moisture & nutrients in soil)

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Real example Plot 1 Plot 2 Plot 3 Branches removed 90 93 101 Poles removed 41 81 97 Poles of better quality left behind standing 80 112 120

Selective thinning & pruning of trees:

Active farmer training: Cut branches & poles from 20m x 20m plot

Initial effects of thinning & pruning on residual stands

Stage 1 Mulomba 0% 50% 100% Observation plots = 0.04 ha (20m x 20m) Stage 2 Catabua 0% 50% 100% Stage 3 Libuni 50% 100% 0%

Catabua stage 2 Catabua stage 2 Aug 2014

Response to 30% & 100% cut after 1 year

30% thinning 100% cut Chinvano stage 2 Chinvano stage 2 Chinvano stage 2 Chividzi stage 3 Mulomba stage 1/2 100% cut This is not deforestation: all species present in system: sprout from dormant rootstocks Degradation is only in terms of stand structure; not in terms of plant diversity Regrowth is productive: many cut plant sprouts grow to >1 m height in 1 year Stems require light for active regrowth & only cut stems respond vigorously Strong demand for light to grow – on edge!

Natural woodland cover Natural woodland biodiversity High High Low Low

Commercial Agriculture All woodland development stages Protected areas Traditional production systems: S&B agriculture & Charcoal SMME’s in integrated, land management systems Commercial Forestry

Conceptual framework for Sustainable development

• f resources within woodlands

Carbon stocks Carbon sequestration rates Soil fertility Soil fertility recovery

Small-scale farmer maintaining mosaic of woodland stages

Regular use of products of different dimensions from different farmer-selected stands as part of silvicultural management

Stage 0 Stage 2 early Stage 2 late Stage 3 early Stage 3 late Stage 4 Cut Stage 1 Prune Thin

Productive use of secondary Miombo woodland while maintaining biodiversity & ecological processes

Integrated management of Timber concessions

Combining harvesting of quality timber, charcoal production, slash- and-burn agriculture & other uses from woodland

Step 1: Cut quality timber Step 2: Charcoal from other trees – in larger gap Step 4: Facilitate tree regeneration in gap Gap diameter = 3-5x canopy height Step 3: Slash & Burn cropping in gap

Develop CONTROLLED sustainable resource use in development zones around national parks and reserves to maintain maximum diversity

Zonation of National Parks by Biosphere reserve concept

Integrating environmental services, ecological processes & use value

• Core area: Unique habitats,

sensitive sites, special ecological or cultural interest, etc

– Minimum interference in system

• Buffer zone (around core area):

Structure/function of natural system not disturbed/changed

– Low-density – high quality ecotourism, minimum interference – Minimum resource use, in tune with natural ecological processes

• Transitional or development zone:

Village areas with controlled traditional resource use practices

– Controlled resource use with moderate disturbance in tune with ecological processes – Facility & craft development for ecotourism (eg lodge structures & curios)

Integrated land use management at landscape scale will maintain woodland diversity, productivity and ecological processes, for both plants and animals, at different levels: farms, villages & districts

Reduce areas of commercial forestry and agriculture, and manage these as out-grower schemes with rural farmers.

Maintain woodland corridors within intermediate – large-scale crop agriculture & forestry

We need changed mindsets to adopt integrated, multiple-use & cost-effective approaches towards recovery of forest & woodland systems

To maintain natural woodland biodiversity & productivity To ensure productive & cost-effective supply of products, values & services; including to sequester carbon at faster rates! Thanks for your interest & attention

• System a better option than REDD+ (climate mitigation action)
• No extra costs to farmer (regular resource use in development stages)
• Farmer remains on land
• Not confined to REDD+ project area & project period
• REDD+ can be aligned with it (high rate of carbon sequestration)