Assessing competition intensity along productivity gradients using a simple model

Abstract

One of the most highly debated issues in plant ecology has been the manner in which competition intensity changes along productivity gradients. We have used a simple model to attempt to demonstrate that in theory, competition intensity can vary quite considerably along productivity gradients. Our model incorporates three key components: (i) changes in resource availability along a productivity gradient, (ii) changes in resource availability when neighbours are removed, and (iii) growth characteristics of the target species and (or) individuals to varying resource levels (i.e., response surface). Variation and interactions among these three components can potentially give rise to various, and occasionally complex, changes in competition intensity along productivity gradients. This partly explains the divergent, and sometimes contradictory, results reported in previous studies.Key words: competition intensity, productivity gradient, nutrient, light, model.