Abstract:
Vast amounts of habitat destruction have already occurred. For instance, about half of all global forest cover has been lost, and forests have virtually vanished in over 50 nations Worldwide. Habitat destruction has been highly uneven among different ecosystems. From a geographic perspective, islands, coastal areas, wetlands, regions with large or growing human populations, and emerging agricultural frontiers are all sustaining rapid habitat loss. From a biome perspective, habitat loss has been very high in Mediterranean forests, temperate forest- steppe and woodland, temperate broadleaf forests, and tropical coniferous forests. Other ecosystems, particularly tropical rainforests, are now disappearing rapidly. Habitat destruction in the temperate zone peaked in the 19th and early 20th centuries. Although considerable habitat loss is occurring in some temperate ecosystems, overall forest cover is now increasing from forest regeneration and plantation establishment in some temperate regions. Primary (old-growth) habitats are rapidly diminishing across much of the earth. In their place, a variety of semi-natural or intensively managed ecosystems are being established. For example, although just two-tenths of the temperate coniferous forests have disappeared, vast areas are being converted from old-growth to timber-production forests, with a greatly simplified stand structure and species composition. Boreal ecosystems have suffered relatively limited reductions to date but are especially vulnerable to global warming. Boreal forests could become increasingly vulnerable to destructive fires if future conditions become warmer or drier.
