Abstract:

Aims: β diversity reflects the differences in species composition among communities, serving as a key indicator linking local and regional biodiversity while characterizing spatial distribution patterns of species. In this study, using data from a large forest observation network in the Xiaoxing’an Mountains, we disentangled the patterns, components, and influencing factors of forest β diversity, aiming to provide a scientific basis for biodiversity conservation in this region. 

Methods: Using the Podani partitioning method, we decomposed β diversity to assess the relative contributions of species replacement and richness difference. We further quantified the local contribution to β diversity (LCBD) and the species contribution to β diversity (SCBD) to identify ecologically unique sites and key species. In addition, regression and variance partitioning analyses were applied to evaluate the relative effects of environmental, spatial and human disturbance factors on community composition, thereby uncovering the ecological mechanisms underlying forest community assembly and biodiversity patterns. 

Results: (1) Species turnover was the dominant process driving community dissimilarity across the study area. Therefore, conservation strategies in the Xiaoxing'an area should prioritize regions with high species turnover rates. (2) The SCBD values ranged from 0.002% to 21.92%, with Betula platyphylla contributing the most and Populus suaveolens the least. Species with higher SCBD values largely overlapped with the dominant tree species in the region. To maintain forest ecosystem stability, targeted management plans should be implemented for the regeneration and harvesting of keystone species such as Betula platyphylla, Quercus mongolica, and Betula dahurica. (3) LCBD values ranged from 0.54% to 2.68%. Plots with higher species richness exhibited higher LCBD values, with southeastern sites generally having greater LCBD values than those in the northwest. Site-level conservation should be prioritized in areas with high LCBD values to preserve the diversity and stability of the Xiaoxing'an forest ecosystem. (4) Climatic factors were identified as the primary drivers of LCBD variation. The interaction between climate, spatial, topographic and human disturbance variables influence water availability and habitat heterogeneity, thereby indirectly shaping species spatial distribution patterns. 

Conclusion: Our findings reveal the spatial patterns and ecological drivers of forest β diversity in the Xiaoxing’an Mountains, highlight key regions and species essential for maintaining β diversity, and provide scientific evidence for forest ecosystem management and biodiversity conservation in this region.

Key words: β diversity, species replacement, richness difference, biodiversity conservation, environment filtering, dispersal limitation