Permafrost Degradation and Ecological Changes Associated with a WarmingClimate in Central Alaska

被引:4
作者
M. Torre Jorgenson
Charles H. Racine
James C. Walters
Thomas E. Osterkamp
机构
[1] ABR,Department of Earth Science
[2] Inc.,Geophysical Institute
[3] U.S. Army Cold Regions Research and Engineering Laboratory,undefined
[4] Univ. Northern Iowa,undefined
[5] University of Alaska,undefined
来源
Climatic Change | 2001年 / 48卷
关键词
Field Sampling; Herbaceous Plant; Ecological Change; Birch Forest; Permafrost Degradation;
D O I
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学科分类号
摘要
Studies from 1994–1998 on the TananaFlats in central Alaska reveal that permafrostdegradation is widespread and rapid, causing largeshifts in ecosystems from birch forests to fens andbogs. Fine-grained soils under the birch forest areice-rich and thaw settlement typically is 1–2.5 mafter the permafrost thaws. The collapsed areas arerapidly colonized by aquatic herbaceous plants,leading to the development of a thick, floatingorganic mat. Based on field sampling of soils,permafrost and vegetation, and the construction of aGIS database, we estimate that 17% of the study area(263,964 ha) is unfrozen with no previous permafrost,48% has stable permafrost, 31% is partiallydegraded, and 4% has totally degraded. For thatportion that currently has, or recently had,permafrost (83% of area), ∼42% has been affected bythermokarst development. Based on airphoto analysis,birch forests have decreased 35% and fens haveincreased 29% from 1949 to 1995. Overall, the areawith totally degraded permafrost (collapse-scar fensand bogs) has increased from 39 to 47% in 46 y. Based on rates of change from airphoto analysis andradiocarbon dating, we estimate 83% of thedegradation occurred before 1949. Evidence indicatesthis permafrost degradation began in the mid-1700s andis associated with periods of relatively warm climateduring the mid-late 1700s and 1900s. If currentconditions persist, the remaining lowland birchforests will be eliminated by the end of the nextcentury.
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页码:551 / 579
页数:28
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