Neighbourhood effects on mortality and diversity in a tropical rainforest

Speaker: Calum Brown (CREEM)

Abstract

Many processes contribute to tree mortality in tropical rainforests, and it is often hard to distinguish them from one another.  Because of their potential role in supporting the coexistence of species, however, they are the subject of much interest and speculation, and it has been suggested that density-dependent mortality caused by species-specific pests or pathogens may alone be capable of producing observed levels of species diversity.  Examples of this effect have been found, but its general strength and form remains unknown.  In particular, its sensitivity to the spatial proximity and genetic relatedness of trees is poorly understood.  We use Bayesian maximum-likelihood modelling to try and identify the causes of mortality in a 50 hectare rainforest plot in Panama, and to look for evidence of different kinds of negative density dependence.  We find¨C11C ambiguous support for several different models, and discuss issues of model¨C12C selection and interpretation.