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Forest-cover change
Eurasia
Boreal forest
Remote sensing
Change processes
Land-use
Deforestation
Products
Fires
Cycle
Map
要旨:
Changes in forest cover have become recognized as an important global environmental issue. This article presents a synthesis of what is known about areas of rapid forest-cover change in boreal Eurasia from the end of the 1990s, based on data compiled from expert opinion and remote sensing data. The broad geographic patterns of rapid forest-cover change have been mapped at regional scale with the characterization of the main causes and drivers of these changes. Around 40 million ha of rapid change areas with clear-cutting activities and 70 million ha with increased fire frequency are depicted. The main processes of rapid forest-cover changes in boreal Eurasia are logging and increase of fire frequency. Ancillary processes are forest conversion for built over area or dam construction, forest regrowths and conversion of bogs. This study revealed that human influence on the Russian forest landscape has been growing over recent decades, mainly as a consequence of logging activities and human-induced fires, with in particular: (i) clear cuts; (ii) high intensity selective logging; (iii) increased fire frequency. Rapid land-cover change is not randomly or uniformly distributed but is clustered in some locations, e.g., high intensity logging mostly takes place in the European part of Russia (e.g., in the Karelian Isthmus) and along the Southern border of the Taiga. Except for forest regrowths on abandoned agricultural land in the southern Taiga, all other processes lead to the decrease of forest cover or to its degradation. Logging activities are driven by regular timber harvesting and irregular cutting for public revenue or individual profit in response to growing demand in national and international markets, particularly in China and Japan. Forest degradation in Siberia, mostly related to increase of fire frequency and development of logging activities, is extending rapidly. Annual forest-cover change rates in areas identified as rapid change areas may range from 0.26% for diffuse logging activities to around 0.65% for areas affected by intense clear-cutting activities, up to 2.3% for areas affected by fires or a combination of fires and logging. While this approach does not directly lead to quantified estimates of forest-cover changes, it highlights those areas where intensive monitoring would be devised for an improved estimation of the changes at continental scale. (c) 2006 Elsevier B.V. All rights reserved. [References: 42]
