The functional role of biological soil crusts on sandy areas of Rio Grande do Sul

Abstract

Biological Soil Crusts (BSC) are of extreme importance in dune areas, as they are recognized as the first colonizers after environmental disturbances. In the Pampa biome, natural geomorphological processes and poor soil use led to the expansion of sediment remobilization areas (Sandization), creating a serious problem - the difficulty of fixing field vegetation and crops. But in this same environment we can find BSC. Thus, this study aims to characterize the types of biocrusts in areas that undergo sandization processes in the Pampa and their possible contributions. We analysed the biocrusts and compared them according to some parameters: soil, geomorphology and aspect. The analyses were carried out between 2014 and 2017 in three sandy areas in the municipalities of Alegrete and São Francisco de Assis. The results show that the majority of BSC found was composed of cyanobacteria (of the filamentous type) on the soil, followed by lichens and mosses in large colonies. The contribution of nutrients to the soil is modified by their presence and they are found in specific features of these sandy areas: on the slopes and slopes of the hills. We found that the presence of these crusts as a source of nutrients and generator of balance leads to the reduction of soil erosion and, therefore, is important for restoring the balance of the biome. This way, the study comprises an exploratory analysis of the BSC through their geoecological behaviour, to initiate studies on the BSC in Rio Grande do Sul, Brazil.