Aspect and slope influence plant community composition more than elevation across forest-tundra ecotones in subarctic Canada
Dates
Year
2017
Citation
Dearborn, Katherine D., and Danby, Ryan K., 2017, Aspect and slope influence plant community composition more than elevation across forest-tundra ecotones in subarctic Canada: Journal of Vegetation Science, p. n/a-n/a.
Summary
Questions: How does treeline community composition vary between elevations, aspects and slope angles in the alpine subarctic and what are the specific abiotic factors governing this variability? How do species richness and rates of community turnover vary from low to high elevation across the forest-tundra ecotone? What do the results indicate about future vegetation change? Location: Kluane Region, southwest Yukon, Canada. Methods: We surveyed plant communities and measured key abiotic variables across forest-tundra ecotones in six alpine valleys, each with a north and a south-facing slope, in two mountain ranges of southwest Yukon. We used non-metric multidimensional scaling to identify patterns in plant community composition and [...]
Summary
Questions: How does treeline community composition vary between elevations, aspects and slope angles in the alpine subarctic and what are the specific abiotic factors governing this variability? How do species richness and rates of community turnover vary from low to high elevation across the forest-tundra ecotone? What do the results indicate about future vegetation change? Location: Kluane Region, southwest Yukon, Canada. Methods: We surveyed plant communities and measured key abiotic variables across forest-tundra ecotones in six alpine valleys, each with a north and a south-facing slope, in two mountain ranges of southwest Yukon. We used non-metric multidimensional scaling to identify patterns in plant community composition and infer which abiotic variables drive these patterns. We calculated species richness and community dissimilarity at regular elevational intervals to assess trends in richness and rates of community turnover within the ecotone. Results: Plant communities varied more with aspect and slope angle than they did with elevation. Aspect-related differences were driven by warmer soil temperatures and deeper active layers on south compared to north-facing slopes, while differences related to slope angle occurred only on north-facing slopes and were driven by soil moisture. Species richness increased with elevation on north-facing slopes and showed no trend with elevation on south-facing slopes. Rates of community turnover were higher on south-facing than north-facing slopes. Conclusions: Plant community composition within the forest-tundra ecotone is driven primarily by soil temperature and, to a lesser extent, soil moisture, both of which vary more in relation to aspect and slope angle than they do between forest and tundra elevations. We recommend that models of vegetation change in subarctic alpine regions address the possibility of change occurring at different rates and in different directions depending on the topographic characteristics of each slope. This article is protected by copyright. All rights reserved.
