Do tree species from the Atlantic Rainforest present negative density dependence due to intraspecific competition via exploration?

Abstract

One of the great interests in Ecology is to understand how so many species can coexist in megadiverse regions, such as tropical forests. One of the main coexistence mechanism is negative density dependence (NDD), which reduces species abundance due to intraspecific competition, Janzen-Connell effects and allelopathy. Most studies that have examined NDD focused on Janzen-Connell effects and little is known about the consequences of other NDD causes. The few studies that explicitly investigated the effects of intraspecific competition have employed spatial point pattern analysis. Overall, they detected NDD due to intraspecific competition of the scramble type. Nevertheless, these studies were conducted for Mediterranean and temperate plant species. Hence, the demographic consequences of intraspecific competition for megadiverse tropical forest species still remain unknown. The goal of the present study is to determine if five tree species of the Lowland Atlantic Rainforest in Southeast Brazil present NDD due to intraspecific competition of the scramble type. To do so, I will use spatial statistics based on the pair-correlation function g(r) with the random labelling null model. I will also use the mark-correlation function º(r) with the independent marking null model. These analyses will enable the evaluation of the spatial pattern of mortality and the size distribution of individuals within populations. (AU)