While many governments try to provide a legislative basis and to realize measures to slow deforestation, the most recent and thorough deforestation studies offer no suggestion that deforestation is decreasing, either of its own accord or in consequence of policy interventions. On the contrary, increasing global integration of markets and growing demand for agricultural commodities and fuel-wood in many regions of the developing world appear to be driving substantial increases in deforestation rates that will result in unsustainable forest management and further declining diverse forest services.
Some models and scenarios predict a substantial 'baseline' deforestation, for example, for 2005-2015 (x 106hayr_1): South America 3.9, Central America 1.2, Southeast Asia 2.6, Africa 5.2, and the total 12.9, with the average annual carbon efflux at the level of 1.2-2.0PgCyr _ during the next two decades. The Special Report of IPCC on LULCC (2001) predicts the average annual accounted carbon stock change due to deforestation at-1.8 PgC yr of which -1.6 PgC yr is expected in the Tropics, and the global result of ARD activities between -1.2 and -1.6PgCyr_ . The ongoing climatic change will accelerate negative consequences of the human-induced deforestation: the expected significant warming by the end of the century suggests dangerous implications for forests and human welfare. Studies report that the warming turns more and more tropical rainforest into steppe, and will transform up to 60% of this forest into dry land, dramatically impacting the region's richest biodiversity. Very likely, a similar process will be accelerated in the forest-steppe ecotone of the Northern Hemisphere, with substantial (up to 30%) increase in the area of the desertified steppe.
Tropical countries can reduce deforestation through adequate funding or programs designed to enforce environmental legislation; support for economic alternatives to extensive forest clearing, including carbon crediting; building institutional capacity in remote forest regions;
and increase in areas of protective forests. Planted forests provide an opportunity to sequester carbon in vegetation and soils: afforestation and reforestation potentially could achieve annual carbon sequestration rates in live biomass in tropical regions 4-8 versus 0.4-1.2 t C ha-1 yr-1 in boreal regions, and 1.5-4.5 tC ha-1 yr-1 in temperate regions. An IPCC scenario (2000) predicts that the maximal amount of carbon that can be sequestered by global afforestation and reforestation activities is 60-87 PgC on 344 x 106ha during the first half of the twenty-first century with 70% in tropical, 25% in temperate, and 5% in boreal forests, provided the average annual carbon uptake is at 1.1-1.6 PgCyr- . Of course, vast areas of forests converted to agriculture use, particularly to pastures, cannot be expected to recover forests of the original type on a timescale relevant to human planning: secondary forests differ in structure, composition, and productivity from their predecessors.
Reducing the rate of deforestation is another major way to decrease GHG emissions. However, neither the UNFCCC nor the Kyoto Protocol has introduced a satisfactory mechanism reducing GHG emissions from deforestation. Avoided deforestation was excluded from the Clean Development Mechanism, and the current international climate policy regime does not provide incentives for developing countries to reduce carbon emissions from tropical deforestation. This problem is under intensive international debates. One of the relevant ways how to curb emissions from deforestation is a so-called compensated reduction of tropical deforestation -the idea that tropical countries might reduce national deforestation under a historical baseline and be allowed internationally tradable carbon offsets having demonstrated reductions. Recent estimates assume that net deforestation would continue until the price of 1 t of sequestered carbon will be less than $100t-1C. Such a price could give a possible decrease of carbon fluxes due to avoided deforestation at 300-650 TgC yr-1.
Tropical deforestation may be decisive in global efforts to stabilize GHG concentrations at levels that avoid dangerous interference in the Earth system. However, it will require substantial international and national efforts in many aspects, for many nations, at all times.
See also: Agroforestry; Alpine Forest; Boreal Forest; Forest Management; Forest Models; Forest Plantations;
Forestry Management; Tropical Rainforest; Tropical Seasonal Forest.
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