
The complex dynamics of interacting biological organisms that form ecological systems make predictions of processes difficult and often imprecise. In this context, Tardif and Shipley explore the acceptability of the biomass-ratio hypothesis, operationalized as community-weighted means, and a new hypothesis (idiosyncratic annulment) for predicting the decomposition of multispecies litter mixtures. They find deviations from expectation but an average bias of approximately zero and a decreasing variability with increasing species richness (SR). They conclude that, since SR increases with increasing spatial scale, the spatial scale will be a determinant in the prediction of ecosystems processes, such as litter decomposition rates.