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Anna Sugden-NewberyMS 2003 Advisor: Monica Turner MS Title: Natural and Anthropogenic Variation in Coarse Woody Habitat among and within Lakes Abstract: Residential development is increasing
in many rural landscapes throughout the US and is often concentrated
near aquatic ecosystems. Therefore, understanding terrestrial-aquatic
interactions may be critical for assessing ecological effects of
development. Introduction of wood from riparian forests into the
littoral zone, where it becomes habitat for aquatic organisms, is
a key terrestrial-aquatic interaction that is not well understood.
We examined the role of forest structure, the abiotic template and
land use on the density of littoral coarse woody habitat (CWH) both
among and within 45 lakes in Vilas County, Wisconsin, USA, that
ranged in building density from zero to 38 houses km-1 of shoreline.
At both scales studied, areas more modified by humans had both a
lower mean value and less variance in density of littoral CWH. Conversely,
areas with little (current) human impact were tremendously variable
– some sites and lakes had abundant wood and others had virtually
none. Among all lakes, littoral CWH density was explained by riparian
CWH, lake shape and conductivity; among low-development lakes, lake
shape and conductivity were replaced in the model by lake area and
the contribution of riparian CWH to the model declined (partial
R2 = 0.43, p = 0.016 versus partial R2 = 0.55, p < 0.001). Among
sites within lakes, littoral CWH presence and density varied with
land-use intensity and exposure to wind. Contrary to previous studies,
there was no relationship between living trees and CWH density,
suggesting that riparian and littoral CWH densities may be strongly
influenced by past disturbance, both human and natural. |
