Influence of environmental factors and fire history on structure, diversity and composition of savanna grasslands.

Abstract

The Cerrado is the richest among the savannas in the world and additionally, the most threatened. The factors that determine the composition and structure of the plant community in vegetation dominated by woody layer are relatively well known, involving complex relationships among climatic and edaphic conditions and disturbance regime. However, there is no evidence that these factors influence are equally determinant of grasslands savanna floristic composition and structure. The general aim of the research is to investigate the relative influence of factors that are shaping savanna grasslands (tree cover under 20%, in dry land), especially in search of distinct patterns of structure, diversity, floristic and functional composition, that are associated to edaphic and climatic conditions or fire history. The study will be carried out in natural remnants of savanna grassland in São Paulo state and marginal states (PR, MS, MG). In each study area it will be carried out the floristic survey, species functional characterization, structural characterization and biomass sampling of community. It will be investigated edaphic factors (soil type, texture, chemical composition and depth), climate factors (annual rainfall, dry season duration, potential evapotranspiration, accumulated water deficit, annual average, maximum and minimum temperatures) and fire history (the number of burnings since 1985 and time gaps since the last burning). The comprehension of these relationships will bring important contribution to advancement of grassland ecology and it can give support to public politics related to environment law, with the creation of protected areas that are representative and protect grassland biodiversity hotspots and, also, to the restoration of these type of plant communities in degraded areas.