Dinâmica florística campestre em anos de precipitações pluviométricas extremas na zona de amortecimento da Estação Ecológica Taim

Abstract

The aim of this study was to understand the effect of soil type on the floristic composition over four years during the winter period in the Buffer Zone of the Taim Ecological Reserve. The Taim Ecological Reserve is an area for the conservation and preservation of fauna and flora, both local and migratory animals, making the private properties around this location also responsible for sustainable production. The experimental area is part of these properties that are located in the Taim Buffer Zone, on the Coastal Plain of Rio Grande do Sul. The experiment took place during the winter period, always in the month following the change of season (autumn to winter), from 2019 to 2022. The experimental area has 0.378 ha, where random 0.25 m² frames were used to evaluate the vegetation (in total, 189 frames were evaluated over the years). The sampling sought to verify the presence and coverage value of the species, through the Daubenmire scale, (from 0% to 100% coverage of the area). In the tables, soil types I, II and III were also measured: I for more sandy soils, II intermediate soils and III low soils, less sandy. The absolute and relative coverage, absolute and relative frequency, richness and diversity indexes (Shannon and Simpson) and Pielou Equability were calculated based on the absolute coverage. The results showed that: The species Adesmia securigerifolia, Axonopus affinis, A. parodii, Briza minor, Cynodon dactylon, Dichanthelium sabulorum, Eryngium nudicaule, Panicum aquaticum, Paspalum lepton, P. notatum, Poa annua, Soliva pterosperma, Sporobulus indicus, Vulpia australis and Kyllinga odorata are persistent over the years in the studied area. Sandier soils have lower diversity. Axonopus parodii is the species with the greatest absolute coverage of the area and Briza minor is the species with the lowest absolute coverage. Over the years, with the variation in environmental conditions, there was a reduction in the Shannon diversity index, but the population remained balanced. Sandier soils have a lower diversity index, compared to less sandy soils, and there is no population balance.