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标题：Factors Affecting the Distribution of Populus balsamifera on the North Slope of Alaska, U.S.A
其他标题：Factors Affecting the Distribution of Populus balsamifera on the North Slope of Alaska, U.S.A
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作者：J. G. Bockheim ; J. D. O’Brien ; J. S. Munroe 等
期刊名称：Arctic, Antarctic, and Alpine Research
印刷版ISSN：1523-0430
电子版ISSN：1938-4246
出版年度：2003
卷号：35
期号：3
页码：331-340
DOI：10.1657/1523-0430(2003)035[0331:FATDOP]2.0.CO%3B2
摘要：Balsam poplar ( Populus balsamifera ) groves occur north of the Brooks Range and treeline in arctic Alaska in a region of continuous permafrost and tundra vegetation. A poplar grove near the Ivishak River (69°06′N, 147°53′W) that we studied in detail contains 11 clones within 350 m of the river. Individual clones range from 600 to 4500 m 2 in size and 90 to 200 yr in age. Poplar trees are larger in diameter in clones within 100 m of the river and less dense in clones away from the river. Unique soil thermal, moisture, and nutrient conditions may limit the expansion of poplar groves to only a few hundred meters from the river channel, including a “thaw bulb,” or depression in the permafrost table; lithologic discontinuities that concentrate moisture in the rooting zone; and accumulation of Ca-enriched precipitates from aufeis deposits. We prepared a map showing the distribution of poplar groves on the North Slope from published reports, satellite images, topographic maps, and observations of a bush pilot. The groves occur within an area bounded by 68–69°N and 142–154°W. A preliminary model explaining the origin and distribution of balsam poplar groves was developed from the case study; unpublished data; and a review of the geologic, hydrologic, and ecologic literature. The groves preferentially occur in areas where there is a sharp change in relief from the Brooks Range to the Arctic Foothills, extensive river braiding accompanied by geothermal springs and aufeis deposits, and a regional groundwater flow system enriched in Ca that may be controlled by faulting.