Temporal shifts on tree species niches: how do they affect species dynamics and community diversity?

摘要

Species-habitat associations can be used as a proxy for species niches. Previous research has shown that niche plasticity may increase diversity in plant communities, and that plasticity may be linked to variations in species fitness. Spatial and temporal aspects of the niche are of interest to understand community structure, but the temporal dimension is often difficult to incorporate in ecological research. In this study, we investigated if species-habitat associations are stable across time, and if they are not, whether niche plasticity promotes variations in species fitness and increases in diversity. We modeled the representativity of 36 species as a function of soil variables and slope in an Atlantic tropical wet forest located in southeast Brazil, as well as their interactions with time, monitored over a period of 17 years. We found niche plasticity to be a common mechanism among the studied species in the studied time period. Niche plasticity was neither significantly related to variations in species fitness nor to changes in species richness, but had a negative effect on diversity when species abundance was accounted for (Shannon and Simpson indexes). We were able to make relevant observations of species-environment relationships over time, such as their niche stability and its effects on the community. We argue that this knowledge is useful in a context of climate change for revealing mechanisms used by plants to cope with environmental oscillations.