United Nations Environment Programme (UNEP)
Global  Environment Outlook-1 - The Web version

Chapter 4: Looking to the Future

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Pressures on Natural Habitats

Past and Present Trends

The results in this section are based on the same calculations as used in the previous section ("Use of Land"), but they focus on non-domesticated areas, a somewhat different classification compared with agriculture and non-agriculture, as was included there.

Between 1700 and 1980, the amount of non-domesticated area decreased globally by more than one third from about 95 per cent to about 65 per cent. (See Figure 4.15.) This was mainly due to the conversion of natural forests and grassland into cropland and pasture. Hannah et al.(1994) found estimates of a similar order of magnitude today for the globe, and Mackinnon and Mackinnon (1986a,b) found similar estimates for Indo-Malayan and Afrotropical realms. Any differences can be explained by different definitions of habitat loss and regional divisions.

In densely populated subregions, such as the western part of Europe (that is, excluding the Nordic countries and Greenland), the losses in non-domesticated area have been considerably larger. Here, the remaining area is less than 30 per cent (Kaales, 1996). And in the Netherlands, only about 20 per cent of the land is not domesticated, of which 9 per cent consists of terrestrial ecosystems and 11 per cent of fresh-water ecosystems (van der Ven, 1996).

The total loss of global forest area (that is, forest and woodland) in the period 1700-1980 is estimated at one fifth, from 47 per cent of the global area in 1700 to 38 per cent in 1980 (Richards, 1990). In temperate zones considerable decline in forest area had already taken place before 1700, especially in the Mediterranean Basin and the Indus Valley (areas occupied by ancient Egyptian, Indian, Greek, and Roman civilizations) and in northern and north-western China (FAO, 1995a). Considerable declines also occurred in north-western Europe during the Middle Ages (Idema et al., 1993).

In contrast to the Mediterranean region, in North America development did not lead to the almost complete loss of forest. Over some 150 years, an initial rapid conversion of forested land was followed by a slowing down in clearance rates, and eventually by a stabilization. In recent decades, there has even been an expansion in the area of forested land, with a considerable amount of the original forest remaining. This reversal reflects a major transition in attitudes and a changing perception of the forest resource, ultimately placing an increasing value on the recreation and wilderness qualities of forests in North America (Mather, 1990). This can be seen as a positive trend, although newly planted forest and wood plantations cannot replace the ecological values of virgin forests.

Currently, primary or old-growth forest (more than 200 years old) is only a small part of the total forest area. Primary forest cover has been greatly reduced in most industrial countries and is rapidly decreasing in developing ones. Old-growth forest is about 1 per cent of the total forest area in Western Europe, about 2 per cent in Scandinavia, about 1 per cent in China, about 15 per cent in the United States, about 25 per cent in New Zealand, and about 52 per cent in Canada (Dudley, 1992).

In developing regions, the average annual decline in forest area between 1980 and 1990 was 0.43 per cent, but the loss of natural forest was 0.8 per cent per annum (FAO, 1995a). The histories of the Mediterranean region (a negative example) and North America (a positive example) illustrate the different patterns of forest use that countries could expect, depending on the approach they follow. Increasing pressure as a result of production, consumption, and population growth will generally lead to a loss of ecosystem quality. For example, forests are losing vitality due to acid rain in parts of Europe, Asia, and North America (NAPAP, 1991). The combined loss of area (quantity) and of ecosystem quality leads to considerable declines in the distribution or population numbers of many plant and animal species.

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