Structure of the tree component in an area of riparian forest in the Piratini River Basin, Rio Grande do Sul, Brazil

The vegetation studied belongs to the Pampa biome. The vegetation of this region is described as Open Arboreal Savanna because it presents a herb stratum and an arboreal stratum with a gallery forest. This study aims to describe the structure of the forest trees of the Basin (31º35’33”S and 53º02’39”W) contributing to knowledge of forest formation in the southern half of Rio Grande do Sul. All living or standing dead individuals in an area of 0.5ha with DBH ≥ 5cm were sampled. Each individual was recorded for its species, diameter at breast height – DBH, and estimated height. Of the 702 living individuals inventoried, 41 species belonging to 25 families were recorded the Myrtaceae family presented the greatest richness with seven species, followed by Salicaceae with four and Lauraceae with tree species. Anarcadiaceae, Asteraceae, Euphorbiaceae and Sapindaceae each showed two species. The other families sampled consisted of a single species only. About 53 individuals were counted dead, corresponding to 7.5% in relation to the quantity of living individuals. The highest importance value was attributed to Lithraea Brasliensis March. The Shannon diversity was estimated to be 2.99 nats (J’=0.81), one of the highest values registered below the 30º south parallel