Poáceas como indicadoras de modificações da vegetação campestre.

Abstract

The aim of this thesis was to collect data about Poáceas as indicators of conservation fields. Areas were chosen in the border region between Brazil and Uruguay in the main managements of livestock animals - grasslands under extensive livestock, fields modified under intensive farming and ranching on native grasslands with low stocking rate, corresponding to the most conserved field found in the study region . A survey phytosociological in the spring and summer of 2011-12, with a modification of the method of points. Each field is subjected to a repeat treatment, where a line was drawn 20 meters and each meter is a registration point of the grass species that touched the metal needle. Since each repetition with minimum size of 300 ha was distributed 20 lines totaling 400 registration points by repetition. To verify the spatial distribution of species of grasses and dissimilarity between sampling units exploratory multivariate analyzes were performed using the methods of Principal Coordinates Analysis and Principal Components for sorting and grouping method for Ward. Using groups was also conducted analysis of variance MANOVA, with Mantel test for the first chapter and test IndVal for the second chapter. In chapter three areas was used as the most representative for the managements in the same region, where there was interference from animal management on vegetation. We conclude that the method of grazing animals and the stocking interfere in botanical composition and species richness of the field. The focus of the second chapter was to evaluate the potential of poáceas as indicators of conservation lands, with assessment at 16 in the three areas studied managements. Found five plant communities, only two highly intensified livestock with exotic forage crops. The others are a little used grassland, medium used and little used. For these groups was identified Paspalum lepton as indicator areas and moderately conserved Cynodon dactylon to areas with degradation.