β-diversity Patterns of Plant Community in Fragmented Habitat in a Degenerated Meadow in Songnen Plain,China

A number of isolated islands of Leymus chinensis + herbosa community were investigated in fragmented habitat islands,by Braun-Blanquet field survey approach,in a degenerated meadow in the Songnen Plain,China in 2007.These islands were classified as large,medium,and small scales on the basis of the island area(100-1000m2,large island;50-100m2,middle island;10-50m2,small island).Each scale of the investigation involved eight islands.The responses of β-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands.The results indicated that at the local community level,there were 57 species belonging to 20 families and 49 genera in large islands,49 species belonging to 16 families and 40 genera in middle islands,and 27 species belonging to eight families and 23 genera in small islands.β-diversity indexes for species,genus and family in large,middle,and small islands varied greatly,and the highest value of the indexes was not noted in the largest island.However,the average of the data obtained at the three scales showed that across large islands,Whittaker indexes were low and Bray-Curtis similarity indexes were high,while across small islands,Whittaker indexes were high and Bray-Curtis similarity indexes were low.At the metacommunity level,Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation(p<0.01) with the island area,whereas the Bray-Curtis indexes for species,genus and family showed a great significantly positive double logarithmic correlation(p<0.01) with the island area.At both local community and metacommunity levels,turnovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family.Hence,the species and the genus could be used for the analysis of β-diversity patterns of plant community.

A number of isolated islands of Leymus chinensis ＋ herbosa community were investigated in fragmented habitat islands, by Braun-Blanquet field survey approach, in a degenerated meadow in the Songnen Plain, China in 2007. These islands were classified as large, medium, and small scales on the basis of the island area （100-1000m2, large island; 50-100m2, middle island; 10-50m2, small island）. Each scale of the investigation involved eight islands. The responses ofβ-diversity patterns of plant taxon to the habitat fragmentation at local community and metacommunity levels were analyzed on different scales of 24 isolated islands. The results indicated that at the local community level, there were 57 species belonging to 20 families and 49 genera in large islands, 49 species belonging to 16 families and 40 genera in middle islands, and 27 species belonging to eight families and 23 genera in small islands, β-diversity indexes for species, genus and family in large, middle, and small islands varied greatly, and the highest value of the indexes was not noted in the largest island. However, the average of the data obtained at the three scales showed that across large islands, Whittaker indexes were low and Bray-Curtis similarity indexes were high, while across small islands, Whittaker indexes were high and Bray-Curtis similarity indexes were low. At the metacommunity level, Whittaker indexes for species and genus showed a great significantly negative double logarithmic correlation （p〈0.01） with the island area, whereas the Bray-Curtis indexes for species, genus and family showed a great significantly positive double logarithmic correlation （p〈0.01） with the island area. At both local community and metacommunity levels, tumovers of species and genus could respond more sensitively to spatial changes of plant diversity patterns than that of family. Hence, the species and the genus could be used for the analysis offl-diversity patterns of plant community.