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Richard Reader 《Environmental management》1988,12(6):803-808
To help determine whether plants should be grouped into guilds for environmental impact assessment, the responses of six members of a guild of deciduous forest herbs to selective tree harvesting were compared. Harvesting operations themselves (tree cutting and skidding) had little effect on five of the six species but the sixth species decreased more in cut plots than in uncut plots. Subsequent microclimatic changes, resulting from tree cutting, also affected guild members differently. In the first year after cutting, two species increased more in cut plots than in uncut plots, while three other species did not change in frequency of occurrence and the sixth species decreased more in cut plots than in uncut plots. This inconsistent response of guild members to tree harvesting suggests that caution should be exercised in using guilds to assess plant response to environmental change. 相似文献
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The response of forest understory vegetation to trampling applied at different temporal and spatial scales was determined
in a cliff-edge forest in Ontario, Canada. Three frequencies (0, 50, 500 passes per year) of short-term trampling (one year)
were applied to plots previously undisturbed. Existing trails that had received three frequencies (approx. 100, 500, 25,000
passes per year) of long-term trampling (18 years) were also studied. Community composition, species richness, and individual
species frequency were recorded in plots within 4 m and (or) 1 m of the patch centerline. The quantitative and qualitative
form of plant response to increased trampling was compared for short-term and long-term treatments, both within 4 m and within
1 m of the path centerline, to judge the consistency of trampling effects at different temporal and spatial scales.
As trampling frequency increased, community composition changed progressively, but consistently, in plots both within 4 m
and 1 m of the path centerline. Species richness was less affected by trampling and only decreased within 1 m of the path
centerline at the highest level of trampling (25,000 passes per season for 18 years). Effects of trampling on individual species
frequency were much less consistent at different temporal and spatial scales of trampling. The scale-dependence results suggest
that field workers and resource managers both should try explicitly to include and define multiple scale components when trying
to ascertain the response of vegetation to human disturbance factors. 相似文献
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