Elevational patterns of multidimensional plant diversity and community structure in a subtropical karst mountain system.

Understanding the mechanisms driving species assembly along elevational gradients in mountains is crucial for biodiversity conservation. However, no consensus has yet been reached on how these mechanisms work. This knowledge gap is particularly pronounced in biodiversity-rich subtropical karst mountains. Integrating multidimensional biodiversity information into research in karst systems will provide new insights into community assembly. Thus, we explored multidimensional forest diversity along an elevational gradient at Jinfo mountain, a karst mountain site, assessing the relative importance of distinct ecological processes in shaping patterns of community diversity and structure. Our results show that different dimensional diversities exhibit similar elevational patterns, with higher diversity observed at low-to-mid elevations than at high elevations. The multidimensional diversity and structure were primarily controlled by climate stress and topographic filtering and were further modulated by soil nutrient limitation and interspecific competition. However, the explanatory weights of these ecological processes were inconsistent among the different dimensions of diversity. The phylogenetic structure was clustered at low and middle elevations, with over-dispersion at high elevations. This indicates that community assembly shifted from being dominated by environmental filtering to being dominated by competitive exclusion as elevation increased. In conclusion, our results demonstrate that combining multidimensional diversity and multiple ecological processes related to community assembly can enhance the understanding of diversity patterns along elevational gradients and the underlying mechanisms maintaining them in subtropical karst mountains.