九连山不同林层β多样性尺度效应及其影响因素OA

[Objective]Long-term research on the impact of snow disasters in southern China on temporal β-diversity in subtropical primary evergreen broad-leaved forests remains limited.This study aimed to investigate the effects of snow disasters on the characteristics,compositional patterns,and underlying drivers of temporal β-diversity in subtropical evergreen broad-leaved forests,thereby providing a scientific basis for post-disaster forest recovery and ecosystem management.[Method]A 4-ha permanent plot was established in Jiulian Mountain,Longnan City,Jiangxi Province,following the 2008 snow disaster.A re-survey of tree species composition,diameter at breast height(DBH),and tree height was conducted in 2022.Temporal β-diversity(including species turnover and species nestedness components)was calculated for different forest layers(dominant,sub-dominant,and understory)and spatial scales(20 m×20 m and 40 m×40 m)between the two surveys.Combined with topographic data and soil physicochemical properties,two-way ANOVA and mixed-effects-based hierarchical partitioning were employed to analyze the mechanisms by which abiotic factors(topography,soil physical properties and soil chemical properties)influence temporal β-diversity across forest layers and spatial scales.[Result](1)Forest layer significantly affected all β-diversity indices,while spatial scale significantly influenced both species turnover and nestedness components.Only the interaction between layer and scale significantly affected species turnover.At both 20 m and 40 m scales,species turnover dominated temporal β-diversity across all layers,with minimal contributions from nestedness.At the 20 m scale,temporal β-diversity and turnover increased sequentially from the dominant to the understory layer,whereas the nestedness component showed a successive decrease.(2)Among topographic factors,altitude significantly influenced the temporal β-diversity of the dominant layer at the 40 m scale.Among soil physical factors,bulk density significantly affected temporal β-diversity across all forest layers at the 20 m scale.Among soil chemical factors,phosphorus(P)and potassium(K)significantly impacted on the temporal β-diversity of the dominant layer at the 20 m scale.(3)At the 20 m scale,soil chemical factors contributed more to the temporal β-diversity of the dominant layer,while soil physical factors contributed more to that of the sub-dominant layer.At the 40 m scale,topographic factors contributed more to the temporal β-diversity and turnover across all layers compared to the 20 m scale.Soil physical factors significantly influenced the temporal β-diversity of the understory layer at both scales.[Conclusion]Following the severe snow disaster,temporal changes in species composition in Jiulian Mountain's primary evergreen broad-leaved forest were primarily driven by species turnover in the sub-dominant and understory layers,rather than by nestedness.Soil chemical and physical factors impacts respectively on the temporal β-diversity of the dominant and sub-dominant layers,respectively,while topographic factors played a more critical role at larger scales.Soil physical factors consistently impacted the temporal β-diversity of the understory layer.This study provides critical insights for post-disaster forest conservation and ecosystem management in subtropical primary evergreen broad-leaved forests.