A comparative approach to predicting competitive ability from plant traits

Abstract

Decades of study of interspecific competition in community ecology has yielded an overwhelming body of special cases but few general principles1–3. This is largely because of the phenomenological, non-predictive approach used4. Further progress requires a predictive approach5 that will enable general principles to be deduced that apply beyond the species and conditions of a particular study or site. General principles are best sought using a comparative approach, that is, the systematic screening of a large number of species under standardized experimental conditions6,7 We used 44 wetland plant species to test whether competitive ability could be predicted from plant traits. Multiple linear regression showed that there was a strong relationship between plant traits and competitive ability (r2 = 0.74). Plant biomass explained 63% of the variation in competitive ability and plant height, canopy diameter, canopy area and leaf shape explained most of the residual variation. This study represents a major step in escaping the current phenomenological approach to competition in community ecology, and provides a general predictive tool for studying competition in natural communities.