中国东部海岛维管植物的beta多样性及其驱动因素

beta多样性描述群落物种组成如何随环境梯度而变化。海岛具有边界清晰、面积和离岸距离不同以及环境变化剧烈等自然禀赋。目前, 我们对离岸距离、岛间距离和气候因素在海岛植物beta多样性变化格局中的相对贡献仍认识不足。本研究基于中国东部36个海岛的维管植物物种名录, 以Jaccard相异性指数度量beta多样性, 利用Mantel偏相关分析和beta多样性的变异分解, 探究了海岛不同生活型维管植物的beta多样性格局及其非生物影响因素。结果显示: 36个海岛共记录维管植物1,404种, 其中木本植物481种, 草本植物859种, 藤本植物64种。植物beta多样性随岛间距离和离岸距离差的增大而显著增加(P < 0.001); 海岛面积和气候要素对植物beta多样性无显著影响(P > 0.05)。岛间距离单独对beta多样性总变异的解释度为29.3%, 离岸距离独立解释了2.8%, 面积和气候共同解释了0.5%。木本植物与草本植物的beta多样性格局与总体一致, 距离因子对木本植物beta多样性的解释度高于草本植物(37.5% > 25.3%)。综上, 海岛植物beta多样性主要受岛间距离和离岸距离的影响, 反映了扩散限制是塑造中国东部海岛植物beta多样性格局的主要生态过程。

Beta diversity of vascular plants and its drivers in sea-islands of eastern China

Plant beta diversity describes how species composition shifts along environmental gradients. Islands are characterized by natural boundaries, variation in size and distance from the mainland, and they also experience intensive shifts in environmental properties. To date, plant beta diversity and its association with influencing factors across islands remain poorly understood. This study examined patterns and abiotic drivers of vascular plant beta diversity across 36 sea-islands in eastern China. Beta diversity was quantified using the Jaccard dissimilarity index based on presence/absence data, and patterns and drivers were analyzed by using partial Mantel tests and the variance partitioning approach. In total, there were 1,404 vascular plant species, including 481 woody species, 859 herbaceous species and 64 liana species. Plant beta diversity increased significantly with increase in cross-island distance and distance difference from the mainland. Differences in both island area and climatic factors did not affect plant beta diversity significantly. Cross-island distance accounted for 29.3% of total variation in plant beta diversity. Distance from the mainland explained 2.8%, and island area and climatic differences together explained 0.5%. The pattern of plant beta diversity was consistent between woody and herbaceous plants, but distance-based variables accounted for more beta diversity variation for woody than herbaceous plants (37.5% > 25.3%). Collectively, cross-island distance and the difference between islands in distance from the mainland are the main drivers of plant beta diversity. This suggests that dispersal limitation plays a key role in shaping plant beta diversity in the sea-islands of eastern China.