Post-fire aspen seedling recruitment across the Yellowstone (USA) Landscape |
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Authors: | Monica G Turner William H Romme Rebecca A Reed Gerald A Tuskan |
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Institution: | (1) Department of Zoology, University of Wisconsin-Madison, Madison, 53706, USA;(2) Department of Forest Sciences, Colorado State University, Fort Collins, 80523, USA;(3) Environmental Sciences Division, Oak Ridge National Laboratory, Oak Ridge, 37831, USA |
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Abstract: | Landscape patterns of quaking aspen (Populus tremuloides) seedling occurrence and abundance were studied after a rare recruitment event following the 1988 fires in Yellowstone National
Park, Wyoming, USA. Belt transects (1 to 17 km in length, 4 m width) along 18 foot trails were surveyed for aspen seedlings
on the subalpine plateau of the Park, along gradients of elevation and geologic substrate, during the summer of 1996. Aspen
seedling presence and density were characterized as a function of elevation, geologic substrate, slope, aspect, vegetation/cover
type, presence of burned forest, and distance to nearest adult aspen stand. Presence of aspen seedlings was best predicted
by the incidence of burned forest and proximity to adult aspen; aspen seedlings were only found in burned forest and were
more likely to occur closer to adult aspen clones. When tested against independent data collected in 1997, the logistic regression
model for aspen seedling presence performed well (overall accuracy = 73%, Taup = 0.41). When present, variation in aspen seedling density at local scales (≤ 200 m) was largely explained by elevation,
with higher densities observed at lower elevations. At broad scales (> 1 km), seedling density was a function of cover type,
elevation, aspect, slope, and burn severity, with greater seedling density in more severely burned forested habitats on southerly,
shallow slopes at lower elevations. Aspen seedling densities ranged from 0 to 46,000 seedlings/ha with a median density of
2,000/ha on sites where they occurred. Aspen seedlings were most abundant in the south central and southwest central regions
of the park, approximately an order of magnitude less abundant in the southeast region, and nearly absent in the north central
area. Establishment of new aspen stands on Yellowstone's subalpine plateau would represent a substantial change in the landscape.
However, the long-term fate of these postfire aspen seedlings is not known.
This revised version was published online in August 2006 with corrections to the Cover Date. |
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Keywords: | Fire ecology Landscape ecology Logistic regression Northern Rocky Mountains Population dynamics Populus tremuloides Spatial extrapolation Spatial heterogeneity |
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