3.5.3.3 forest resources - deforestation

what are the causes of deforestation?

- exploitation above the MSY
- clearance for alternative land use

how fraction of the world's original forest area has been lost due to human activities?

1/3

timber

- commercial logging industry produces timber for industrial processing and possibly for export

- hardwood species e.g teak and mahogany grow more slowly than conifers so it is more difficult to commercially manage hardwood plantations as it may take longer to produce a saleable crop

- therefore a lot of the harvested hardwood come from mixed forests that are clear felled and may not be replanted

agricultural expansion causes the loss of forests in two main ways:

- the growth of the local population increases demand for food so more land must be cleared for farming

- forest clearance for commercial cash crop agriculture where the produce may be taken to cities or exported

examples of commercial cash crop agriculture

- rainforest clearance in South America to grow sugar cane and soya beans or to ranch cattle

- rainforest clearance in SE Asia to grow palm oil

subsistence farming

- many of the families that clear rainforest to farm used to live on the land that was taken over by commercial agriculture

- when poor people in LICs are growing food to feed their own families, restricting access to land may increase poverty

- solution may be to help maximise production on the land that is used rather than clear more and help with social improvements that raise living standards and slow population growth

cash crop commercial agriculture

- rising affluence and a better transport infrastructure can make almost any large area of land with reasonable soils and climate valuable fore food production

- growth in demand for beef, arable crops and biofuels e.g palm oil increase demand for farmland

mineral extraction

forest clearance for mining and the associated infrastructure affects a relatively small total area but it can have important local impacts

reservoirs

reservoirs for public supply, irrigation, or HEP can replace forests

e.g the expansion of HEP in South America has caused the loss of large areas of tropical rainforests

urbanisation

- the expansion of urban areas can cause the direct loss of forest

- increases demand for fuel and food which can cause further forest loss

transport infrastructure

the area of forest lost by the construction of roads, railways or airports is not large but they can have other impacts

- roads and railways can create barriers to the movement of wildlife and cause population fragmentation

- improved transport systems increase accessibility and make it easier to take out resources such as felled trees or agricultural produce that may increase the rate of forest clearance

fuel

- many people in LICs cannot afford alternative energy sources and have to use wood

- there may be a greater demand for charcoal that produces less smoke when burnt in cities and towns

- the production of charcoal involves the partial combustion of wood with a shortage of air

- much of the energy value of the world is lost in this process which increases the rate of forest clearance to satisfy the demand for energy

livestock fodder

- in LICs, in areas of mixed woodland and grassland farmers may cut branches off trees if there is a shortage of ground level grazing

- if this exceeds the growth of the trees then the forest may gradually be degraded and disappear