Abstract:

Aims: Understanding the fundamental processes that underlie biogeographic patterns of biodiversity has long been a central issue in biogeography and ecology. It is widely accepted that niche processes and neutral processes work together to regulate the plant β-diversity. However, the relative influence of different ecological processes on plant taxonomic, functional, and phylogenetic β-diversity in the black gobi desert region of China remains poorly understood. This lack of understanding hinders our comprehension of the assembly processes and the maintenance of plant diversity in gobi deserts. 

Methods: We selected 67 sites within the typical distribution area of the black gobi desert region of China. Through systematic field surveys and laboratory analyses, we collected data on plant species abundance, six key leaf and fine root functional traits, and molecular phylogeny. Results: Plant taxonomic, functional, and phylogenetic β-diversity exhibited significant distance-decay patterns, with functional β-diversity showing the strongest relationship with geographic distance. Null model analysis indicated that the taxonomic β-diversity of plant community in the black gobi desert region of China displayed a random distribution pattern, suggesting that it is primarily governed by neutral processes. In contrast, functional and phylogenetic β-diversity exhibited non-random distribution patterns, indicating that niche processes dominate plant functional and phylogenetic assembly. Notably, phylogenetic and functional β-diversity were decoupled in the black gobi desert region of China. None of the six functional traits exhibited significant phylogenetic signals, suggesting that the functional traits of gobi plants have not been conserved through evolutionary processes. Furthermore, variance partitioning analysis indicated that both soil and climatic factors jointly determined plant community β-diversity, with annual precipitation and solar radiation exerting a stronger influence. 

Conclusions: Our results indicated that the relative roles of niche processes and neutral processes in shaping the patterns of plant β-diversity in the black gobi desert region of China vary among different dimensions. In addition to water-energy factors such as annual precipitation and mean annual temperature, solar radiation also emerges as an important driver for the plant β-diversity. Taken together, our findings highlight that the ecological drivers of plant diversity may differ among various dimensions and that solar radiation plays a key role in shaping plant diversity in the extremely harsh gobi desert environments.

Key words: black gobi desert, taxonomic β-diversity, functional β-diversity, phylogenetic β-diversity, null model