The Changing Alpine Treeline
：The Example of Glacier National Park, MT, USA
( Volume 12 )
Publication subTitle ：The Example of Glacier National Park, MT, USA
Publication series ：Volume 12
Author： Butler David R.;Malanson George P.;Walsh Stephen J.
Publisher： Elsevier Science
Publication year： 2009
E-ISBN: 9780080957098
P-ISBN(Paperback): 9780444533647
P-ISBN(Hardback): 9780444533647
Subject： P5 Geology
Language： ENG
Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.
Description
The alpine treeline ecotone (ATE) is an area of transition high on mountains where closed canopy forests from lower elevations give way to the open alpine tundra and rocky expanses above. Alpine tundra is an island biome and its ecotone with forest is subject to change, and like oceanic islands, alpine tundra is subject to invasion – or the upward advance of treeline. The invasion of tundra by trees will have consequences for the tundra biome as invasion does for other island flora and fauna. To examine the invasibility of tundra we take a plant’s-eye-view, wherein the local conditions become extremely important. Among these local conditions, we find geomorphology to be exceptionally important. We concentrate on aspects of microtopography (and microgeomorphology) and microclimate because these are the factors that matter: from the plant’s-eye-view, but we pay attention to multiple scales. At coarse scales, snow avalanches and debris flows are widespread and create “disturbance treelines whose elevation is well below those controlled by climate. At medium scales, turf-banked terraces create tread-and-riser topography that is a difficult landscape for a tree seedling to survive upon because of exposure to wind, dryness, and impenetrable surfaces. At fine scales, turf exfoliation of the fronts of turf-banked risers, and boulders, offer microsites where tree seedlings may find shelter and are able to gain a foothold in the alpine tundra; conversely, however, surfaces of n
Chapter