Composição florística, estrutura e rendimento da biomassa de plantas forrageiras em áreas de Caatinga

Abstract

Research is needed to define the structure and dynamics of the caatinga, especially floristic and phytosociological studies in order to organize conservation actions of native vegetation, as well as the comparison of floristic composition of areas, without and with the presence of domestic cattle. The aim was to analyze the floristic and phytosociological parameters and to estimate the aerial biomass yield of shrub and tree plants with forage potential in Caatinga áreas in Paraíba Cariri, Brazil. The evaluated area was subdivided into three areas: Area I (10 goats), Area II (5 goats) and Area III (0 goats). For the phytosociological survey, the contiguous plots method was used. All plants with total height ≥ 1 m and diameter at the base of the stem ≥ 3 cm were sampled. Phytosociological data were processed through the Mata Nativa 2 program. After the survey, 8 individuals of Croton sonderianus, Poincianella pyramidalis and Aspidosperma pyrifolium were selected, species with forage potential. The perimeter was measured at soil level, the length of the major axis of the crown projection area and its longest orthogonal axes, the total height of the plant, the crown and its insertion. Also, mathematical models were created, relating the biomass to the measurements, using the individual variables and different combinations of plant measurements using multiple linear regression. The families and species of areas I, II and III were shown to be uniform. The values of the Shannon and Pielou indexes were similar, showing that the areas are in similar stages of succession. Aspidosperma pyrifolium obtained the highest values of crown length (cl) and crown percentage when compared to the values obtained by Poicionela pyramidalis and Croton sonderianus, which may be related to the diameter at the soil level (DSL) of the species. The general equation for leaf weight parameters 1.60 m (LW160) and total leaf weight (LWTOTAL) in both natural matter (NM) and dry matter (DM) had a high coefficient of determination (R2 = 0,88) for LWS160 and (R2 = 0.85) for LWTOTAL. Studied areas are similar, floristic and phytosociologically. Multiple linear regression is a good predictor to determine the aerial biomass yield of caatinga trees.