Tree diversity in Minas Gerais, Brazil

Abstract

Minas Gerais State (MG), the fourth largest Brazilian State, with size comparable to countries such as France and Spain, harbors a great environmental heterogeneity and consequently tree diversity. The current thesis was structured into three chapters. The first one consists of an overall description and literature review on the main ecological points underlying this study. The second and third chapters are scientific papers on tree diversity in MG. We used 158 vegetation sample areas, including different phytophysiognomies of the following three vegetation domains found in MG: Cerrado, Atlantic Forest and Caatinga. The first paper, entitled “Tree Dominance and Diversity in Minas Gerais, Brazil”, approaches some basic but neglected questions regarding MG tree diversity: how many trees and tree species are there in MG? How much of such diversity has been lost? We used a grid of 6,634 cells (0.1 degree) and Fisher’s alpha and Fisher’s log-series to run the estimates. We found that there are currently 24.5 x 10 9 trees and something between 3,592 and 3,743 tree species in MG. Besides, we’ve found 68.54% and 4.03% to be lost when compared to the estimate original numberss. These results enable us to create abundance-distributions maps and, for instance, find out the most abundant tree species in MG: Qualea grandiflora. The second paper, entitled “Water availability drives gradients of tree diversity, structure and functional traits in the Atlantic-Cerrado-Caatinga transition, Brazil”, approaches how vegetation features such as species composition in different taxonomic levels, diversity, stem density, basal area, seed mass and wood density are correlated with environmental gradients in terms of soil and climate. PCA axes were used as proxies to infer about environmental gradients, and four major gradientes were detected as representatives of precipitation seasonality, temperature range, soil fertility and soil moisture. Regarding vegetation, the tree species composition and diversity, were closely related to precipitation seasonality and soil moisture. Thus, the availability of water was found to be the main determining factor for vegetation features under study. Therefore, these results may be important in the implementation of initiatives for vegetation conservation in the State, and for ecological comprehension of vegetation transitional areas.