M. Jonsson et B. Malmqvist, Ecosystem process rate increases with animal species richness: evidence from leaf-eating, aquatic insects, OIKOS, 89(3), 2000, pp. 519-523
Effects of species number and identity on the breakdown rate of leaf litter
were estimated in a laboratory experiment using leaf-eating insects, three
species of Plecoptera, as detritivores. We found significant differences b
etween the different species on this process in single-species experiment;
but not when animal biomass was accounted for. When species were combined t
he effect of species identity was strongly reduced and rendered insignifica
nt, whereas the number of species had a significant effect. This shows that
rates of ecosystem processes may benefit from species richness even when a
ll species belong to the same guild, which is in contrast to hypotheses pre
dicting redundancy within guilds. Facilitation between species and negative
interactions, where intraspecific interactions are greater than interspeci
fic interactions, are two potential mechanisms which could explain increasi
ng decomposition rates with species richness.