SREL Reprint #1883





Relative Importance of Mechanisms Determining Decomposition in a Southeastern Blackwater Stream

Duke University Wetlands Center 16139 Okeechobee Boulevard,
Loxahatchee, Florida 33470

Savannah River Ecology Laboratory, Drawer E,
Aiken, South Carolina 29801


Department of Biology, Auburn University at Montgomery, Montgomery, Alabama 36117

ABSTRACT.-Cliemical inhibitors were used to separate the effects and determine the relative importance of microbial degradation, flow-related fragmentation, and shredder fraginenta6on on sweet gum (Liquidambar slyraciflua) decomposition rates in Upper Three Runs, in South Carolina. 'A'e correlated several abiotic and biotic variables (current velocity accumulation of inorganic and fine particulate organic matter, water depth, bacterial density and shredder biomass) with the decomposition of individual sweet gum leaf packs. NA'e also surveyed the biomass and density of shredders in natural leaf accumulations and in constructed leaf packs to help determine the importance of shredders in decomposition.

Except for accumulated sediments (inorganic and fine particulate organic matter, FPOM), none of the independent variables, including base-flow current velocity and shredder biomass, were significantly correlated with decomposition of individual sweet gum leaf packs. Sediment accumulation was inversely related to decomposition rates. Experimental analyses suggested that microbial degradation dominated the decomposition processes. A constant flow regime characterized bN, low current velocities, plus a depauperate shredder abundance, accounted for the relatively minor role of shredders and flow-related fragmentation.

SREL Reprint #1883

Rader, R.B., J.V. McArthur, and J.M. Aho. 1994. The relative importance of mechanisms determining decomposition in a southeastern blackwater stream. The American Midland Naturalist 132:19-31.

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