Tropical forests cover about 1,680 million ha: 920 million ha in tropical South and Central America, 490 million ha in Africa, and 270 million ha in tropical parts of Asia and the Pacific. Dense evergreen forests account for 720 million ha, dense semi-deciduous forests cover 590 million ha and dryland forests cover 240 million ha (see Table 1). Current deforestation rates are estimated to vary from 0.7%/year in tropical South and Central America and Africa to 1.1%/year in tropical parts of Asia and the Pacific. Degraded forest areas cover more than 2 million ha.
Table 1: The current estimated global area of natural tropical forests
Type of forest |
Asia and the Pacific |
Africa |
South America and the Caribbean |
Total | |
Humid tropical forest |
219 |
338 |
870 |
1,427 |
(85%) |
Dryland tropical forest |
41 |
151 |
46 |
238 |
(14%) |
Mangroves |
7 |
3 |
6 |
16 |
(1%) |
Total natural tropical forest |
267 (16%) |
492 (29%) |
922 (55%) |
1,681 (100%) |
(100%) |
Note: all figures are in millions of hectares. Sources: FAO (1993, 1994 and 1995).
Sustainable forest management is an objective of forestry policy in most countries irrespectively of the degree of human intervention in forests, consequently any discussion of sustainable forest management should include natural forests, secondary forests and forest plantations.
This type of forest is used in many different ways. Uses range from fairly low intensity harvesting regimes (for example local hunter-gathering communities) to more intensive harvesting of non-wood forest products and game and commercial logging of varying intensities. Shifting cultivation is a type of forest use that can cause forest degradation, particularly if it practised using unsustainable techniques. Numerous similarities exist between regions and continents, although there are also some marked differences. In Africa, commercial forest operations have opened up roads and trails into the heart of vast previously untouched areas of forest, which are then penetrated by slash and burn farmers where population pressure is high. In South America, livestock ranching is considered to be one of the important drivers of deforestation. In Southeast Asia, overharvesting of stands containing large volumes of commercial timber is an important and often sufficient cause of forest degradation.
Deforestation and degradation of dryland forests are caused by several man-made, climatic and biological factors. Drought conditions, combined with tree felling (mainly for conversion of forestland to agricultural uses), overharvesting of fuelwood and grazing, are the main causes of soil degradation and eventually lead to desertification. An estimated 70% of dryland forest areas in the tropics are affected by desertification, which leads to increased impoverishment of tree populations. This process is further accelerated by deliberate and accidental brush fires.
The establishment of forest plantations can meet a number of needs, including: carbon fixing; the provision of a wood supply source that is an alternative to the natural forest; the restoration of degraded land; and the generation of income and employment. About 28 million ha of forest plantations in tropical areas can be considered as forest plantations for wood production. These plantations are mainly located in the humid tropical zone. A number of agricultural tree crops can also be considered as commercial plantations (including: rubber; coconut; and oil palm plantations). It is also currently estimated that more than 500 million ha of degraded land could be planted (or replanted) with trees. However, current rates of forest plantation establishment are only about 1.7 million ha/year (see Table 2).
Table 2: Industrial forest plantation area in 1995
Area of forest plantations for industrial wood production (in million ha) |
Annual increase in total forest plantation area (in million ha) |
Proportion of total forest plantation area used for industrial wood production | |
Africa |
2.43 |
0.12 |
52 % |
South America and the Caribbean |
5.97 |
0.23 |
76 % |
Asia and the Pacific |
19.11 |
1.30 |
45 % |
TOTAL |
27.51 |
1.65 |
FAO (1997).
Secondary forests are defined as woody formations occupying land where human intervention has destroyed the original natural vegetation (usually natural forest). At the end of the 1990's, there were 65 million ha of secondary forest in tropical South and Central America, 90 million ha in Africa and 87 million ha in tropical parts of Asia. This resource, although very important in many countries as a source of wood fibre, represents one of the most serious challenges for forest managers and policy-makers. This is because so little is known about how to effectively manage these areas, particularly in tropical regions. For example, forest cover can be restored naturally with adequate levels of forest protection. However, such a process would probably take hundreds of years before the forest regained its original structure and functions.
