Abstract:

Identifying the mechanisms that drive community structure and dynamics is one of the most fundamental goals in ecology. The local neighborhood in which trees grow significantly influences species survival. In order to understand the mechanisms underlying the various survival responses to neighborhood crowding among species, we compared the survival responses of focal tree species through modeling tree survival in terms of neighborhood effects. These effects were quantified in different ways, based on the survival monitoring and functional trait data of 90 species commonly observed in a lower tropical evergreen broad-leaved forest 20-ha plot in the Dinghu Mountains. We found that among all species tested, 58% showed sensitivity to neighborhood effects and that the survival response of 50% were mediated by functional trait differences among co-occurring species. Shade tolerance of species is associated with species sensitivity to its neighborhood as species with lower shade tolerance are intended to be sensitive to their neighbors. Lower specific leaf area, higher leaf dry matter content, wood density and maximum diameter at breast height indicate higher shade tolerance. Niche difference associated with light acquisition strategies may underlie species coexistence at the neighborhood scale. Our study provides new insights into quantifying neighborhood interaction and species coexistence at the local neighborhood scale.

Key words: neighborhood crowding, survival response, trait difference, functional trait, shade tolerance