felling in the European part of Russia (72 per cent).
Boreal forests are very poor in species but in general have been little affected by human activity (see Chapter 9). One problem area is permafrost, where changes in vegetation (through logging for example) can cause melting. Until relatively recently, logging has been scattered and the forests are so huge that regeneration was achieved through natural regrowth. However, in recent years in the Russian Federation, where timber is one of the country's major exports, logging has increased enormously, generally by clear cutting, causing serious erosion problems and changes in plant and animal habitats. These forests are under increasing threat from internal mismanagement and the short-term opportunism of foreign companies (Dudley, 1992). Because of the low level of harvesting technologies, large amounts of wood are wasted (about 50 per cent) and left on the spot. Much of the logging is fostered by giant timber companies from South Korea, the USA and especially Japan. The amount logged (often clear felled) reached 40 000 km2 each year, or as much as the annual deforestation in Brazil (FAO, 1992). In 1991, ten Japanese firms signed a five-year agreement with the Russian Federation to harvest in Siberia 6.5 million m3 of timber per year for export (MacKenzie, 1994). In addition to the destruction of the forest resource, forest clearing releases large amounts of carbon dioxide and methane to the atmosphere. With the forest destroyed, it can no longer absorb carbon dioxide from the atmosphere through tree growth (see Box 23F).
Siberia's forests are also being depleted by fires, affecting at least 10 000 km2 each year. Being situated in high latitudes in the far north, where the greatest potential temperature rises in the northern hemisphere are expected from climate change (see Chapter 27), boreal forests could soon suffer marked desiccation, making them even more vulnerable to fires (Myers, 1993).
It is often pointed out (Dudley, 1992) that, although northern industrial countries have made tropical timber producers adopt a policy to sell timber only from sustainable managed forests in a new International Tropical Timber Agreement (see Box 23E), similar restrictions do not exist for the protection of their own forests.