Mechanisms of monodominance in diverse tropical tree-dominated systems

Abstract

1. The existence of many types of monodominant forests is readily explainable by ecological theory (e.g. early successional forests). Nevertheless, monodominant stands sometimes occur in areas where a much higher diversity typically occurs. Such 'classical monodominance' is not currently readily explained by ecological theory.

2. We briefly review the published mechanisms suggested to cause classical monodominance and then combine them into a new probabilistic conceptual framework to better understand why these systems occur. We build on two theories proposed to explain monodominance: a lack of exogenous disturbance over long periods and species-specific life-history traits. We suggest that certain traits under certain conditions may generate positive feedbacks leading to a greater probability of monodominance being achieved. Such positive feedbacks have the potential to drive a typically diverse system towards a monodominant one.

3. Synthesis. Classical monodominance in tropical forests is hypothesized to be attained when a group of traits occur together under low exogenous disturbance conditions, this giving rise to a series of positive feedbacks. The presented framework links the differing mechanisms proposed in the literature to explain classical monodominance and shows there are potentially alternative routes to monodominance, thus reconciling apparently contradictory observational and experimental results.