Edge effects of landscape fragmentation on the shrub-layer vegetation in the One-Thousand Island Lake
千岛湖破碎化景观中灌木层植被的边缘效应

Landscape fragmentation often lead to edge effects on ecosystems.Edge effects of shrub-layer plants on islands in typical fragmental area of Thousand-island Lake were analyzed.On 10 less-disturbed and more isolated islands,shrub-layer plant species was selected as study object and composition and abundance of the shrub-layer species were recorded by quadrate method.The results of one-way variance analysis(ANOVA) showed that richness of species differed significantly((F=23.386,) P=0.000<0.01).Specifically,both plant abundance and species richness in edge environment were higher than those in interior environment.The plant species diversity for the two environments were quantified using Shannon-Wiener Index(H),Simpson Index(D),and Pielou Evenness Index(E).For the edge,H=2.304,D=0.883,and E=0.880;for the interior,H=1.716,D=0.751,and E=0.755.Clearly,plant species diversity was higher at the edge than the interior of the islands.Also,several species,such as Vitex negundo L.var.cannabifolia,and Rubus swinhoei Hance,were only found in the edge environment.The measure of species similarity between the edge and interior varied greatly(B=0.300,0.800]).This indicates that the plant species diversity of at least some of the islands has been significantly affected by landscape fragmentation.Further analysis using Spearman correlation showed that the shrub-layer plant species richness was not significantly correlated with island area in either the edge or interior environment.