Structure and composition of northern grasslands in South Brazil

Abstract

To contribute to the understanding of grassland formations in the southern Brazilian plateau, a floristic and structural survey was carried out in communities in its northern region. This region is characterized by a climate regime of transition between temperate and subtropical, within the phytogeographic zone called Campos Gerais. The study was carried out in grassland communities in the Guartelá State Park (Tibagi, Paraná State, Brazil - 24º39’10” S and 50º15’25” W), with the allocation of 90 sample units of 1 m2, distributed in 30 plots in the dry grassland (CS), 30 in rocky outcrops grassland (CR) and 30 in a wet grassland (CU). A total of 128 species and 28 families were found, with the occurrence of 66 species in CS, 55 in CR, and 64 in CU. Although the number of species sampled was higher in CS, there was no significant difference between grasslands for richness and diversity. Asteraceae (28 species), Poaceae (24), Melastomataceae (13), and Cyperaceae (11) were the families sampled with the highest species richness, a common pattern in grassland areas of the Mata Atlantica and Cerrado biomes. Few species were high frequency and coverage in the communities (mainly grasses) among several low biomass and low-frequency species. In addition, a marked zonation of vegetation was observed due to topographic and edaphic variations, since the greatest similarity was between CS and CR (54.54%) and dissimilarity between CR and UC (21.84%). Despite this, 10% of the species were found in common for CS, CU, and CR, an index higher than that found in studies carried out in the region. Floristic and structural differences in local and regional communities reinforce the need for further studies on the plateaus of southern Brazil for a more detailed understanding of this vegetation since its complexity is little known and the strong anthropic pressure has significantly affected its area of occurrence.