Forests are influenced by climate, landform and soil composition and they exist in a wide variety of forms in the tropical, temperate and boreal zones of the world. Each forest type, evergreen and deciduous, coniferous and broadleaved, wet and dry, as well as closed and open canopy forests, has its own uniqueness and together these forests complement one another and perform the various socio-economic, ecological, environmental, cultural and spiritual functions.Recent surveys on a global basis suggest that there are about 1.4 million documented species, and the general consensus is that this is an underestimate - perhaps 5 - 50 million species exist in the natural ecosystems of forests, savannas, pastures and rangelands, deserts, tundra, lakes and seas. Farmers' fields and gardens are also importance repositories of biological resources.In this context, it has been acknowledged that forests are rich in biological resources. Though covering only 13.4 per cent of the Earth's land surface, these forests contain half of all vertebrates, 60 per cent of all known plant species, and possibly 90 per cent of the world's total species. However, recent studies have shown that temperate and boreal forests with their extremely varied ecosystems, especially those in climatic and geographical areas where old-growth forests still occur, may be even more diverse than tropical forests in terms of variation within some species. Eventhough temperate and boreal forests generally have far fewer tree species than tropical forests, often having a tenth or less in total, certain temperate and boreal forests are now thought to be as diverse, or even more diverse, than their tropical counterparts. For example, old-growth forests in Oregon, U.S.A. are found to have arthropods in leaf litter approaching 250 different species per square meter with 90 genera being found in the H.J. Andrews Memorial Forest research area alone (Lattin, 1990). It has been suggested that a network of 500 protected and managed areas, with an average size of 200,000 hectares, covering 10 per cent of the remaining old-growth/primary forests be the minimum acceptable target (Anon, 1991IUCN/UNEP/WWF, 1991).To enhance this networking and to optimise the global representativeness of these biogeographic areas for the conservation of biological diversity, a list of these areas based on mutually agreed terms by national governments should be formulated. It should also include the identification of these biogeographic areas and the development of joint mechanisms, as well as the quantification of the costs involved and the identification of sources of fund needed to manage and conserve these areas. Joint mechanisms for possible international cooperation to establish transboundary biogeographic areas should also be implemented.