Abstract
Two contradictory niche-based processes, environmental filtering and competitive exclusion, are important ecological processes in community assembly. Quercus wutaishanica forests are the climax communities in the Qinling Mountains and the Loess Plateau, China. Since these areas are characterized by different climate and evolutionary histories, these forests could be a suitable study system to test the phylogenetic niche conservatism hypothesis. We compared variation in community assembly of two distinct Q. wutaishanica forest communities and analyzed how the variations are formed. Quercus wutaishanica forest communities had significantly different species pool, phylogenetic structure and phylogenetic diversity between the two regions that were driven by inconsistency in environment conditions and evolutionary history at the local scale. Soil ammonium nitrogen, soil water content, and nitrate nitrogen play a major role in phylogenetic beta diversity patterns. The effect of environmental filtering on community assembly was more significant on the Loess Plateau than in the Qinling Mountains. Our study also found that local environment is important in mediating the patterns of phylogenetic structure. These findings provide insights into the mechanisms of local community assembly.
Highlights
Community assembly has been one of the central topics in plant community ecology for decades.There are two main theories to explain the process of assembly
Niche-based theory predicts that assembly of plant communities is mostly a deterministic process and that the patterns of species coexistence may be affected by environmental filtering or competitive exclusion [1,2]
In the Niubeiliang region (Qinling Mountains) we collected 730 individuals belonging to 107 species, and in the Ziwuling region (Loess Plateau) we collected 226 individuals belonging to 37 species (Table S1)
Summary
Community assembly has been one of the central topics in plant community ecology for decades.There are two main theories to explain the process of assembly. Community assembly has been one of the central topics in plant community ecology for decades. Niche-based theory predicts that assembly of plant communities is mostly a deterministic process and that the patterns of species coexistence may be affected by environmental filtering (referring to abiotic factors that prevent the establishment or persistence of species at a particular location) or competitive exclusion (referring to interaction of species within community) [1,2]. Neutral theory suggests that stochastic processes act on assembly [3] and the structure and composition of a community are mainly constrained by probabilistic dispersal, ecological drift, or historical inertia [4]. Limiting similarity and environmental filtering are two contrary niche-based mechanisms that occur simultaneously along various environmental axes during deterministic assembly, even within Several researchers have considered that both neutral and deterministic processes may shape community assembly patterns [5,6,7], the deterministic process was regarded as a main process during assembly [8], in temperate regions [9].
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