Avaliação da diversidade de espécies vegetais na região costeira do posto administrativo da praia do Bilene

Abstract

The present study was carried out at the Administrative Post of Praia do Bilene with the aim of evaluating the diversity of plant species, considering floristic and phytosociological aspects associated with soil characteristics. For the vegetation survey, the area was stratified into 6 types of vegetation cover, where 10 x 10m plots were installed and the diameters at breast height (DBH) of all individuals with DBH ≥ 5cm were measured and individuals with DBH were recorded. <5cm and H ≥1m. In the 10 x 10m plots, 1m 2 subplots were installed to record herbaceous species. To determine the spatial pattern and soil analysis, 10 x 30m plots were used, in each plot soil samples were collected at 3 points along the diagonal, with two replicates for each depth (0 to 20 and 20 to 40cm). 185 species were registered, among which, shrubs (30.27%), herbs (29.19%) and trees (17.30%), had a greater number of species. The families that had the largest number of species were Poaceae (18), Fabaceae (17), Asteraceae (13), Rubiaceae (13), Cyperaceae (9), Apocynaceae (8) and Phyllanthaceae (6). The most important and frequent species were Afzelia quanzensis, Albizia adianthifolia, Apodytes dimidiata, Mimusops caffra, Flacourtia indica, Albizia versicolor, Garcinia livingstonei, Sclerocarya birrea, Strychnos madagascariensis, Phoenix reclinata, Panicum maximum, Blotella natalisis, Smagrost. Imperata cylindrica, Bulbostylis hispidula and Sporobolus virginicus. The highest absolute density (DeAb) of species with DBH <5 cm was found in the riverside cover with 8142.90 ind.ha -1 and dense cover with 6318.18 ind.ha -1. For species with DBH ≥ 5cm, the highest DeAb was found in the dense cover with 1800 ind.ha -1 and moderate coverage with 1411.11 ind.ha -1. The largest basal areas occurred in the dense and moderate coverage with 20.82 m 2 .ha -1 and 13.66 m 2 .ha -1, respectively. The diametric distribution of the dense, modern and riverside roofs was in the form of “J-inverted”. The values ​​of diversity of Shannon-Wiener were higher for the riverside cover (3.48) and dense (3.34) and lower for the herbaceous cover (1.07). The pielou equitability value ranged from 0.84 to 0.77 and a richness index from 9.27 to 1.56 for riverside and herbaceous coverings, respectively. In the sampling of herbaceous species, the cover with the highest DeAb value was the herbaceous with 65.24 ind.m 2, followed by the low cover with 26.63 ind.m 2 and the grassland with woody with 18.25 ind.m 2. The wealth index ranged from 6.12 for grassland with wood to 3.54 for low coverage and evenness ranged from 0.86 for riverside coverage to 0.75 for low coverage. The diversity index value was higher for riverside coverage (2.92) and lower for low coverage (2.19). The soils of the Bilene Beach Administrative Post in the study area are sandy, acidic, non-saline with a low to very low organic matter content