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PARENT SESSION
Thursday, August 10, 1:30-5:00 pm
COS 98 - Forest and habitat fragmentation
L-5, L-6, L-7, Lobby Level, Cook Convention Center
Presiders: A Radomski and C Tripler

Defining edge gradients using plant species composition in oak-hickory forest patches.

Tulloss, Elise*,1, Meiners, Scott1, 1 Eastern Illinois University, Charleston, IL

ABSTRACT- Forest conservation is greatly enhanced with an increased understanding of the transitional nature of edges. Most forests in east-central Illinois exist as small patches, making the region an ideal location for studying edge effects. The objective of this study was to identify the mechanisms and processes that determine gradients of plant composition and to develop a predictive model of edge effects using plant species composition as an indicator of edge influence. A large data set was gathered to relate species composition to several environmental and community composition variables. The data was analyzed in several multiple regressions to find the most important variables controlling edge responses. The study system had a sharply defined edge gradient, with vegetation cover highest at the edge and decreasing dramatically 15-30 meters into the forest. Percent canopy cover, distance from the edge, and plot slope were the most important controllers of edge influence for most responses. Edge aspect had no effect on the response of the community. Canopy cover controlled light intensity on the forest floor, distance reflected the plot landscape position, and slope reflected the control of microtopography on plant growth. An ANCOVA found that total cover did not change with distance on plots with steep slopes. Besides providing a useful tool for predicting the effect of the edge on plant composition, this study also found microtopography to be an important controller in this system, which has previously been overlooked in the study of edge effects.

Key words: edge effects, eastern deciduous forest, predictive model

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