Condições edáficas em gradientes de altitude determinam a distribuição de espécies arbustivas – Arbóreas

Abstract

The study evaluated the role of edaphic variables in the structure, composition, and pattern of plant community richness in two mountainous regions of Serra de Bodocongó (7º 27 '6 "S, 35º 59' 41" W) and Serra da Arara ('8.12' S and 36 ° 23'36.74 'W) both located in Paraíba, Brazilian semi-arid. For Serra de Bodocongó, 21 plots of 4 x 50 m distributed randomly along the altitude gradient were demarcated. While for Arara 50 permanent plots were divided into two transects along the altitudinal gradient. In each plot, soil samples were collected for fertility analysis and soil granulometry at three different points of the plot. Diversity indexes and structural parameters were calculated for both areas. Linear regression analyzes showed a pattern of soil fertility decline along with an increase in species richness with increasing altitude. The analysis of canonical correspondence indicated the formation of two distinct floristic groups, the first with some dominant species, typical of the regions of the base of the mountain, associated with higher levels of fertility and higher values of pH, whereas a second group formed by species less abundant, and typical of more preserved Caatinga areas associate d with low soil fertility rates. Our results indicate that the edaphic variables play a determining role in the assemblage of plant communities in the mountainous regions of the Brazilian semi - arid region.