G. Loss of Biodiversity
There are over half a dozen main causes of biodiversity loss; those related to the partial or total destruction of habitat are the most serious. Between 1700 and 1980 there was a loss of over one-third of the area covered by natural diverse ecosystems, mostly due to agricultural and grazing of land. Densely populated areas in countries of more affluent economies showed a much higher loss. The Nordic countries and the Netherlands today possess less than 30% of the original area of non-modified ecosystems. In the Netherlands, only one-third of that extinction is represented by diversified ecosystems, the rest being fresh water or salty water from dikes produced by man.
2. In Developing Countries
Loss of habitat, especially forested ones, is much higher and will keep being so in developing countries where most of the biological diversity of the world is located. The history there is very simple. You've seen it and heard about it very often-- modification of systems that are extremely species rich. An example of this is southern Chiapas which is very close to the border of Guatemala and the borders of the reserve of Montesasulias near Chahul.
The near future of many of these areas is the tearing down and burning and there is a
conversion to extremely inefficient grassland systems in which people can grow one or two cows per acre at the most, but that will give them some kind of livelihood. There is the loss of topsoil with the more serious erosion problems in areas with everything that entails.
3. Frontier Forests
A very recent estimate of the World Resources Institute regarding the so-called frontier forests that are undisturbed natural wooded communities show that this transformation has been really enormous. The total loss of such forests in the world has been extremely severe. The light green areas here are the original forested systems of the world. The dark green is the present day areas covered by forests. You can see that really the extent of forest and community loss has been monumental in the world.
The area of original terrestrial habitats per capita in the world is expected to decline from the current 1.8 hectar level to 1.1 hectar in year 2015 and to less than to 0.8 hectares per capita in year 2050 (UNEP 1997). So, this ratio really tells you about the pressures that the population is having and also the pressure that the future population growth will have in these areas.