Landscape Management - Details of Forest Conditions

University of Washington

Global and Regional Forest Conditions - Details

There are 3.4 billion ha of forests in world, covering approximately 26.6% of the world’s land area.

1. Maps of the world’s forest cover.

2. The data on global forest conditions comes from the Food and Agriculture Organization’s (FAO) biennial State of the World’s Forests (SOFO). The most recent edition was published in 1999, although some data from the 1997 SOFO are also used here. Link to FAO SOFO for information from 1997 and 1999. The FAO uses a bottom-up approach for global forest assessments in which data are compiled from national forest inventories, standardized for comparison, and summed. Some global forest assessment projects use a top-down approach in which data are generated at regional, continental, or global scales through satellite imagery. The International Geosphere-Biosphere Project (IGBP) and European Commission’s Joint Research Centre (JRC) global forest resource assessment projects are examples of the top-down approach. Because of differences in definitions of forest cover, sources of data, and methodologies for vegetation classification, the statistics obtained by different projects may not be directly comparable.

3. The FAO State of the World’s Forests uses the following definitions (FAO, SOFO 1999 Annex 2):

Forests: Includes natural forest and forest plantations. Land with tree crown cover (stand density) of more than ~20% of the area; continuous forest with trees usually growing to more than ~7 m height and able to produce wood.
Deforestation: Change of forest with depletion of tree crown cover to less than 20%.

Global and Regional Forest Conditions - Details

The world’s forests are not equally divided among political, socio-economic, and biogeographic regions. Some areas, such as Russia and South America, contain vast amounts of forests, while others such as the Caribbean Islands and North Africa have almost no forest.

Global and Regional Forest Conditions - Details

Between 1990 and 1995 there was a net loss of approximately 56 million ha of forest area (1.6% of the total forested area of the world); however, some regions increased in forest area, while others declined. Recent evidence suggests that the rate of deforestation may be slowing down.

1. Net forest loss from 1990-1995 was 11.3 million ha per year; however, this includes an annual increase of 1.7 million ha per year in developed countries. Total forest loss in developing countries (where most of the deforestation occurs) during 1990-1995 was 13.7 million ha per year. For the period 1980-1990 FAO reported an annual decrease in forest area of 15.5 million ha per year in developing countries. While the rate of deforestation in developing countries appears to have decreased by ~10% between the two periods it remains to be seen if this is a trend that will continue or whether it was a consequence of variability in the collected data. While the 2001 SOFO will provide a clearer picture of global deforestation rates, preliminary data released by FAO in the Forest Resources Assessment stated that for the period 1990-2000 net annual deforestation was ~9 million ha per year, a reduction of nearly 20% over the 1990-1995 estimates.

2. Deforestation can be defined in several different ways. In its State of the World’s Forests the FAO (SOFO 1999 Annex 2) defines deforestation as a “change of forest with depletion of tree crown cover to less than 20%.” Others have defined deforestation as the permanent removal of the forest cover (Ford-Robertson 1971). In this sense deforestation is the act of converting forests to desert, permanent agricultural or grazing lands, eroded barrens, or urban environments; and concomitantly, the temporary removal of trees through natural disturbances (e.g., fire, windstorms, insect infestations, floods) or human disturbance (e.g., shifting agriculture, forest management) is not considered deforestation. Global forest assessments of forest cover and rates of change will be strongly influenced by the manner in which forests and deforestation are defined.

Ford-Robertson, F.C. (editor). 1971. Terminology of forest science, technology, practice, and products: English language version. Multilingual forestry terminology series No. 1, authorized by the Joint FAO/IUFRO Committee on Forestry Bibliography and Terminology. Published by the Society of American Foresters, Washington, D.C.

Global and Regional Forest Conditions - Details

Economically underdeveloped regions experienced the greatest amount of forest loss, while economically developed countries experienced substantial net gains in forest area.

Global and Regional Forest Conditions - Details

Global wood consumption is ~3.4 billion cubic meter per year or ~1 cubic meters of wood per hectrare per year (Figure 1); however, not all forests are harvested at the same rate (Figure 2). Some forest types contain little area reserved from harvest, while others contain large reserves (Figure 3).

Figure1:

Figure 2:

Within the United States there are notable contrasts among regions in both the amount of wood produced and the amount of that growth that is harvested. Some regions, such as the Rocky Mountains, have very little harvesting (relative to amount of forests), while other regions, such as the southeast, harvest the majority of their growth.

Figure 3:

Within the United States there are also regional differences in the amount of different forest types protected in reserves.

Global and Regional Forest Conditions - Details

Approximately 57% of the world’s wood consumption is for fuelwood. The remainder of the global wood consumption is largely for building materials and pulp and paper products.

Global and Regional Forest Conditions - Details

Ninety percent of global fuelwood consumption occurs in economically underdeveloped countries and is a major contributor to the net forest loss experienced in those regions.

Global and Regional Forest Conditions - Details

Regionally, there is a surplus of small-diameter, low-quality wood and a shortage of large-diameter, high-quality wood. A high proportion of the Pacific Northwest’s forests are second-growth forests or plantations that are <70 years old and are becoming overcrowded and increasingly susceptible to windthrow, insect outbreaks, or catastrophic fires (e.g., summer 2000). The data shown in the graph below include only those lands considered to be productive forest lands, i.e., timberlands; this does not include reserved forests such as National Parks and other protected areas.

In Pacific Northwestern USA there is an excess of stands in the dense structure.

Page Updated: Monday, February 12, 2001 - 07:14 PM