Plant diversity on islands is associated with habitat heterogeneity, the distribution of a species, the flood pulse that may be influenced by fluvial dynamics and differences in geomorphologic origin. This study assessed the diversity of trees on six islands of the Paraguay River, between Caceres and Taimã Ecological Station, in the Pantanal, Brazil. Islands created by two geomorphologic processes were compared: sedimentation and islands formed when the necks of meanders erode. All of the trees with DBH > 5 cm were sampled from 22 (10 m x 20 m) plots (per island), which were 50 m from each other. Ten plots were allocated in the central parts and 12 on the edges of the islands in areas where there was erosion and sediment deposition. The cluster constructed from the Sorensen coefficient resulted in dendrograms based on single bonds and Euclidean distance of similarity indexes, where hierarchies were observed among the groups when considering the plots located in the center and on the edge of the islands, and between islands. Forty species belonging to 34 genera and 21 families were recorded. The Shannon-Weaver diversity indexes ranged from H' 1.08 to 2.77. There was a difference in the floristic composition on the islands that were formed when necks of meanders eroded compared to those formed by sedimentation. There was a difference in the floristic composition when comparing the center and edge of islands formed when necks of meanders eroded.
Pantanal; islands; arboreal vegetation; geomorphologic origin; flood pulse
