Abstract:

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.

Key words: island area, Jaccard index, cross-island distances, distances from the mainland, climate, dispersal limitation