Composição florística e produção de matéria seca em um remanescente de campo nativo na localidade no Ponche Verde

Abstract

Grasslands are one of the most extensive biomes of the world, covering an area of approximately 39 million km ², about ¼ of the terrestrial surface. The floristic composition of these environments are mainly grasses (Poaceae), associated with several species of other botanical families, many having potential of forage. The objective of this study was to evaluate the floristic composition and dry matter production in native grasslands. The study was developed in a private property of 72 hectares, in the Ponche Verde sub-district, Upacaray locality, 28 km to the south-central municipality of Dom Pedrito, Rio Grande do Sul State, Brazil. For the realization of the work, it was used an area of 16 hectares remaining of native pastures destined to the cattle raising. The botanical surveys were carried out in the period from 16 November 2016 to 20 March 2018. To evaluate the occurrence of the species, was used the “Método de Caminhamento”. Was evaluated to estimate the native pastures growth rate and a better analysis of the species found in the region through the dry matter inside and outside the grazing exclusion cage, which measuring 1.0 × 1.0 m. Four samples of forage were collected for each cage, one internal sample and the other three around the cage, all cut at ground level using a metal frame measuring 0.5 × 0.5 m to delimit the area and a shear to cut, 16 samples per collection, totaling 48 samples at the end of the experiment. A total of 158 species belonging to 28 botanical families were identified. The most abundant families are Poaceae (= Grasses) and Asteraceae (= Composites). Of these species, 72 species are native dicotyledon non-forage species, 44 native monocotyledon forage species, 17 native dicotyledon forage species, 12 native monocotyledon non-forage species, 3 native leguminous species, one exotic leguminous species and 4 toxic-invasive-exotic species. The dry matter production inside the exclusion cages were in the cage 1, 2 and 3, respectively: 346.8g, 201.2g and 246.8g, while outside the cages the dry matter indices were the following: 145.72g, 186.16g and 157.32g. The total percentage of dry matter for the functional groups was the following: 37% native non-forage dicotyledon, 25% dry material, 22% native monocotyledon forage, 7% native dicotyledon forage, 6% native non-forage monocotyledon, 2% native leguminous 1% toxic-invasive-exotic.