Global change effects on a mechanistic decomposer food web model
Kuijper, L. D., Berg, M. P., Morriën, E., Kooi, B. W. and Verhoef, H. A. 2005.
Global change effects on a mechanistic decomposer food web model.
Global Change Biology 11: 249 - 265
Abstract
Global change may affect the structure and functioning of decomposer
food webs through qualitative changes in freshly fallen litter. We
analyzed the predicted effects of a changing environment on a dynamic
model of a donor-controlled natural decomposer ecosystem near Wekerom,
The Netherlands. This system consists of fungi, bacteria, fungivores,
bacterivores and omnivores feeding on microbiota and litter as well.
The model concentrates on carbon and nitrogen flows through the trophic
niches that define this decomposer system, and is designed to predict
litter masses and abundances of soil biota. For modeling purposes, the
quality of freshly fallen leaf litter is defined in terms of
nitrogenous and non-nitrogenous components, of which refractory and
labile forms are present. The environmental impacts of elevated CO2,
enhanced UV-B and eutrophication, each with their own influence on leaf
litter quality, are studied. The model predicts steady-state dynamics
exclusively, for all three scenario's. Environmental changes impact
most demonstratively on the highest trophic niches, and affect
microbiotic abundances and litter decomposition rates to a lesser
extent. We conclude that the absence of trophic cascade effects and
non-equilibrium dynamics may be attributed to weak trophic links
occurring in the system. We set out a number of experimentally
testable hypotheses that may improve understanding of ecosystem
dynamics.