On community matrix theory in experimental plant ecology

Abstract. In multi-species communities the stability of a system is difficult to assess from field observations. This is the case for example for competitive interactions in plant communities. If a mathematical model can be formulated that underlies the processes in the community, a community matrix can be constructed whose elements represent the effects of each species onto every other (and itself) at equilibrium. The most common competition model is the Lotka-Volterra equation set. It contains interspecific competition coefficients to represent the interactions between species. In plant community ecology several attempts have been made to quantify competitive interactions and to assemble a community matrix, so far with limited success. In this paper we discuss a method to use pairwise interaction coefficients from experimental plant communities to analyse feasibility and stability of multi-species sets. The approach is contrasted with that of Wilson and Roxburgh (1992) and is illustrated using data from Roxburgh and Wilson (2000a). Results from Wilson and from this study differ (some times substantially), with our approach being more pessimistic about stability and coexistence in plant communities.