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Consumer responses to resource patch size and architecture: leaf packs in streams

Richardson, John S. and Chauvet, Eric Consumer responses to resource patch size and architecture: leaf packs in streams. (2019) Fundamental and Applied Limnology, 192 (3). 255-261. ISSN 1863-9135

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Official URL: https://doi.org/10.1127/fal/2019/1187

Abstract

Accumulations of leaf litter in freshwaters can vary from individual leaves to large leaf packs. Past studies have demonstrated that decomposition rates decrease as leaf pack size increases. We considered a set of hypotheses that lower breakdown in larger leaf packs occurs as a consequence of diffusion gradients of oxygen and nutrients, or lower accessibility to larger detritivores to leaf tissue in the middle of these leaf packs. We manipulated leaf pack size in a stream to quantify decomposition rates and the abundances of consumers relative to the amount of detrital mass available. Mass loss rates of beech leaves were lower as leaf pack size increased. We found no differences in fungal biomass across our treatment gradients, or when comparing leaves in the middle of the leaf pack versus those on the outside. The lower decomposition of larger leaf packs would thus not result from a lower quality of the resource based on fungal biomass. Invertebrates per unit mass of leaf packs declined exponentially with size of leaf pack. Smaller invertebrates were less abundant per unit of resource as leaf pack size increased, but abundances of larger invertebrates declined even more dramatically than that of smaller ones. The results are consistent with accessibility within leaf packs decreasing as leaf pack size increases, a factor that is important for the estimation of consumer-resource functions for this patchy resource.

Item Type:Article
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
Other partners > University of British Columbia (CANADA)
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Deposited On:30 Oct 2019 12:57

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