FITOSSOCIOLOGIA E DIVERSIDADE DO COMPONENTE ARBUSTIVO-ARBÓREO DE UMA ÁREA DE RESERVA LEGAL DA CAATINGA

Abstract

The aim of this research was to know the phytosociology and taxonomic diversity of the shrub-tree component in a Caatinga legal reserve and to evaluate the relationship between population species in edaphic characteristics. A phytosociological survey was carried out, allocating 25 systematized plots with an area of 400m² each. The inclusion criterion for the individuals assessed in the plots was the circumference at breast height ? 15,8 cm and height (> 1.5 m). The tree community of the study area was analyzed for richness, abundance, composition, diversity (using the Shannon index – H’), evenness (using the Pielou index – J’), and phytosociological parameters of the species (basal area, density, frequency, dominance, coverage value, and importance value). Additionally, within each plot, soil samples were collected at two depths (0-20cm and 20-40cm) for laboratory measurement of 13 physicochemical edaphic variables. The relationship between species abundance and plot edaphic variables was assessed through Redundancy Analysis. A total of 570 individuals were sampled, distributed in 13 species, 13 genera, and 6 families. The most representative families were Euphorbiaceae and Fabaceae. The species Cenostigma microphyllum and Mimosa tenuiflora stood out as the most abundant and frequent, recorded in 92% and 96% of the plots, respectively. These species prevailed in all the phytosociological parameters analyzed. The diversity index recorded for the study area was considered low (H’= 1,79) compared to those of other anthropized areas in the Caatinga, as well as the evenness value (J’= 0,69). The results of abundance, diversity, and evenness, combined with the results of the phytosociological parameters, indicate ecological dominance of C. microphyllum and M. tenuiflora. The abundance of the species M. tenuiflora and Aspidosperma pyrifolium correlated positively with the edaphic variables sum of bases and electrical conductivity, while the abundance of Commiphora leptophloeos and Pseudobombax simplicifolium correlated inversely with these variables The abundance of Cnidoscolus quercifolius and Jatropha mutabilis correlated negatively with the sand variable.