Padrões espaciais de diversidade de Leguminosas (Fabaceae) e seus determinantes climáticos

Abstract

Diversity patterns are very sensitive to current climate and past climate changes. The Leguminosae is directly tied to Neotropical vegetation, therefore this family can be considered representative of these environments. Our study sought for a diversity pattern for Leguminosae in Minas Gerais State and southern Bahia State, Brazil, as well as the (climatic) driversof this botanical family, the shifts in past climate and the possibility of formation of ecoregions. Data were gathered from InventárioFlorestal de Minas Gerais database together with the database from Laboratório de Conservação e Manejo da Biodiversidade (UFLA). Climatic variables were obtained from WorldClim database. We analyzed patterns of species richness, abundance and basal area of Leguminosae, as well as their relative values and the importance of the climatic variables in such patterns. Additionally, we analyze past climatic patterns from 6000, 22000 and 12000 years ago. In order to define ecoregions we performed a cluster analysis (dendrogram) and a species indicator analysis for the groups we found. We have not found clear patterns for the absolute values of species richness and abundance of Leguminosae in Minas Gerais and southern Bahia. Concerning relative values, we observed higher representativeness in the northern area. With regards to basal area, for both absolute and relative values we found a different pattern, with higher values in the south and in the north and lower values in the central Minas Gerais. Additionally, we found that higher representativeness is mostly related to a lower precipitation and/or higher temperatures. Representativeness in past climate when extrapolated to South America display a higher dominance of Leguminosae in Northeast Brazil and in Chaco region. Cluster analysis pointed out three different groups, reflecting the distribution of semi-deciduous forests, Cerrado sensulato, and deciduous forest in Caatinga Domain. We may conclude that there is a higher representativeness of Leguminosae in the north of Minas Gerais State and southern Bahia State occasioned mainly by higher temperatures and lower precipitation. Therefore, we can say the composition of Leguminosae reflect occupied vegetation domains.