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  • 标题:Tilt of Spruce Trees near Ice Wedges, Mackenzie Delta, Northwest Territories, Canada
  • 其他标题:Tilt of Spruce Trees near Ice Wedges, Mackenzie Delta, Northwest Territories, Canada
  • 本地全文:下载
  • 作者:S. V. Kokelj ; C. R. Burn
  • 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:2004
  • 卷号:36
  • 期号:4
  • 页码:615-623
  • DOI:10.1657/1523-0430(2004)036[0615:TOSTNI]2.0.CO%3B2
  • 摘要:Ice wedges are common in the Mackenzie Delta, although troughs may be filled by sediments and obscured by growth of vegetation. At four sites in eastern Mackenzie Delta, over 85% of the trees within 1 m of ice-wedge troughs leaned towards these troughs. The mean angle of lean was 12° from the vertical, with some trees leaning by more than 25°. The angle of tree tilt varied inversely with distance from the ice-wedge trough and most of the trees over 1 m from an adjacent trough leaned away from the ice-wedge. Trees near the troughs are susceptible to toppling because their root systems trail away from the troughs. Reaction-wood rings in cross-sectional disks from trees leaning towards troughs indicated that progressive tilting has been sustained for decades to centuries. Long-term rates of tree tilting are estimated to be between 0.1 and 0.4° a −1 . Progressive, unidirectional tilting may eventually destroy the spruce trees. In Mackenzie Delta, where forest fire is infrequent, earth movements associated with ice-wedge polygons may be one mechanism driving forest change in old-growth stands.
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