3.5.3.2 forest resources - the relationship between forest productivity and biodiversity

mixed species plantations

wildlife biodiversity is increased by growing multiple species because there is an increase in food choices, inter-species relationships and niches

selective logging

different trees will be ready for felling at different times in mixed species plantations or natural forests

- more expensive because it is more labour intensive but it gains the maximum benefit from the forest timber resource over longer time periods

- good for wildlife because the removal of individual trees leaves small clearings which have a smaller impact on the survival of remaining wildlife populations

- wildlife that has lost it tree habitat will not have to move too far to find a new habitat

what is an example of sustainable forestry?

Programme for Belize that manages 100,000 hectares of rainforest in Belize called the Rio Bravo Conservation and Management Area

what is the main goal of the Programme for Belize?

the conservation of the rainforest and the sustainable use of its natural resources

cultivation of non ingenious species

- trees selected for cultivation are often non indigenous

- these may be better adapted to the environmental conditions and are less likely to suffer damage caused by pests or disease

- growing non indigenous species is less likely to support indigenous wildlife species because there inter species needs for food, pollination, seed dispersal or habitats are less likely to be met

examples of non indigenous forestry plantations

UK: Sitka Spruce and Douglas Fir (originally from North America), Corsican Pine (originally from Souther Europe)

Central America: Teak (originally from Asia)

East Africa: Eucalyptus (originally from Australia)

single species plantations (green desert monoculture)

- growing a monoculture of one tree species can make management of a plantation easier

- activities such as planting and felling can be carried out over larger areas at the same time

close planting

- planting all the seedlings close together makes the trees compete with each other for light so they grow tall and straight

- the low light levels at ground level inhibit growth of other plants that may compete with the trees for water or nutrients

- loss of these plants and the species that depend upon them reduces the wildlife diversity of the forest

simple age structure - benefits

- planting large areas of trees at the same time makes management easier as the trees will all be of similar sizes and will all need similar management activities at the same time

- the trees in commercial plantations are usually felled when the income will be greatest, this is normally when they are approaching full size and growth rate is starting to decline

- natural forests contain old trees with dead wood that supports many invertebrates and the species that feed on them

simple age structure - negatives

- having trees of a similar size reduces the variety of abiotic factors compared with having a plantation with trees of different ages and sizes

- this reduces the biodiversity of wildlife species that can survive

sustainable forest management strategies

- mixed species plantations
- indigenous species
- mixed age structure
- selective logging

harvesting rates - maximum sustainable yield

the rate of resource removal must not be greater than the MSY

the MSY can be increased by using an agricultural approach to forest production

- select species that grow quickly
- use selective breeding to enhance growth and quality
- control tree spacing
- increase nutrient supplies
- control pests and predators

this may increase MSY but not necessarily the broader environmental sustainability

indigenous species

if indigenous species are cultivated it is more likely that other indigenous species will benefit e.g birds and insects

mixed age structure

- having a plantation with trees of different ages produces a greater diversity of abiotic factors e.g light levels, wind velocity and temperature

- this increases the biodiversity of other species living in the forest

what have the Programme for Belize done to conserve the rainforest?

- use of heavy machinery is limited and does not include bulldozers

- each tree has a unique identification tag, which allows the timber to be tracked from its original location to its final retail destination such as a DIY superstore in the UK

- surplus timber offcuts are supplied to local craftsmen e.g buttress roots are carved into tourist souvenirs or branches for furniture making

- a tree nursery is used to replan within the receiver and to provide saplings for local communities

- reserve rangers patrol the reserve to control illegal logging

- access paths are as narrow as possible and avoid important trees, including their root systems

what is the negatives of the Programme for Belize?

good for wildlife but could threaten the local communities that used to use the area for:
fuelwood supplies
timber for house building
farming clearings
hunting for food
the collection of medicines and fibres

how is the threat to local communities being managed (PfB)?

- a range of economic activities have been developed or encouraged

- local people are employed in forestry and ecotourism actives within the serves

- ecotourist groups visit local restaurants, are fed on local produce and buy locating made souvenirs

what wood is in the highest demand in Belize rainforest?

mahogany but the programme are trying to encourage the use of other species to trade