浙江天童常绿阔叶林林冠结构与群落物种组成的关系

Aims The ecological mechanisms underlying species compositional differences among communities are crucial to understanding and predicting biodiversity changes. One of such mechanisms is the spatial structure independent of ground-level habitat (e.g., soil nutrients and topographic parameters). However, the primary drivers of this spatial structure are still unclear. Forest canopy structure can alter understory microclimates, which in turn influences the spatial structure and species compositional differences. We know little so far about such influence of the forest canopy structure. This gap has hindered our understanding of the ecological mechanisms underlying species compositional difference. Methods The study was conducted in a 20 hm²evergreen broadleaf forest plot in the Tiantong region, Zhejiang Province, Eastern China. UVA-based LiDAR was used to estimate the high-precision forest canopy structure of the Tiantong plot. The redundancy analysis and the variance decomposition method were used to explore the relative importance of forest canopy structure and other potential factors on community species composition. Important findings Our research showed that: (1) In the case of excluding the effect of canopy structure, the spatial structure independent of the ground-level habitat was one of the main contributors to the species compositional differences in the Tiantong plot. It explained 25.2%, 28.1%, and 8.0% of the variation in species composition at the scales of 100 m², 400 m², and 2,500 m², respectively. (2) Including the effect of forest canopy structure significantly reduced the explanation power of the spatial structure by about 1/3 (26.2%-36.0%). (3) Among canopy structure factors, canopy height had the most significant influence on species composition, followed by internal canopy structure. With the increase of the plot scale, the effects of canopy height decreased while the impacts of internal canopy structure increased. In conclusion, our study demonstrated that canopy structure is one of the main drivers of spatial structure independent of ground-level habitat. Our results also clarify the relative importance of canopy height and internal canopy structure on species composition and provide new perspectives to understand the ecological mechanisms underlying species compositional differences among forest plant communities.