HR: 0800h
AN: B31A-0977    [Abstracts]
TI: Ecosystem Consequences of Forest Fragmentation in the Pacific Northwest: Biogeochemical Edge Effects within Old-Growth Forest Remnants
AU: * Hayes, T D
EM: thayes@uwsp.edu
AF: University of Wisconsin-Stevens Point, Treehaven Environmental Learning Center, W2540 Pickerel Creek Road, Tomahawk, WI 54487 United States
AU: Swanson, A
EM: swansonalan@hotmail.com
AF: Montana State University, Department of Statistics, Bozeman, MT 59717 United States
AU: D'Antonio, C M
EM: dantonio@lifesci.ucsb.edu
AF: University of California- Santa Barbara, Department of Ecology, Evolution, and Marine Biology, Santa Barbara, CA 93106 United States
AU: Griffiths, R P
EM: Bob.Griffiths@oregonstate.edu
AF: Oregon State University, Department of Forest Science, Corvallis, OR 97331 United States
AB: Our research includes quantifying the long term impact of clear-cut edges on biogeochemical processes affecting carbon and nitrogen retention within fragmented old-growth Douglas-fir/western hemlock forests in the Pacific Northwest. In addition to quantifying the magnitude and depth of influence of edge effects on soil processes, this research seeks broader application to conservation biology, using a mechanistic approach. Along 360-m gradients spanning clear-cut to forest at nine sites, long-term monitoring of edge effects integrates microclimate, above-ground structure, litter fall, decomposition, and soil nitrogen dynamics. Abrupt changes in height and structure at edges induce increased microclimatic variability in adjacent forest, which, in turn, alters rates of nitrogen and carbon cycling in soils. Field and laboratory assays reveal increases in litter decomposition and nitrogen availability in near edge (0-30 m from edge) forest, and higher rates of litter fall and soil organic matter storage within far edge (30-120 m from edge) forest, relative to interior forest (more than 120 m from edge). Abiotic structural effects, by modulating microclimatic variability, change the complex biotic interactions involved in biogeochemical cycling in forest soils within 120 m of edges. Due to such interactions, organic-matter and nitrogen pool sizes in soil and vegetation, and net ecosystem production, vary in a nonlinear, but predictable, manner with distance into forest from edge. Mixed-effects statistical models most precisely quantify depth of influence for over 100 microclimatic, structural, and biogeochemical variables.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0439 Ecosystems, structure and dynamics (4815)
DE: 0469 Nitrogen cycling
DE: 0476 Plant ecology (1851)
SC: Biogeosciences [B]
MN: Fall Meeting 2005