Estrutura fitossociológica do estrato lenhoso e da regeneração natural em área de caatinga no Município de São Mamede - PB.

Abstract

The aim was to carry out a floristic and phytosociological study of the arboreal and regenerating stratum and to show the floristic similarity among them; to evaluate the phytosociological parameters of the arboreal stratum and to differentiate them according to the inclusion criteria adopted by the Rede Manejo da Caatinga and Rodal, in a fragment of caatinga that has been degraded and is preserved at one year in the Ecological Reserve Verdes Pastos, São Mamede-PB municipality. All woody individuals with CAP ≥ 6 cm, CNB ≥ 9 cm and height ≥ 1 m were surveyed in 15 plots of 20 x 20 m. For natural regeneration all individuals with CNB <9 cm were surveyed in 30 subplots of 2 x 2 m allocated in zigzag form within the plots of the phytosociological survey. In the woody stratum were sampled 1,016 individuals using the first sampling criterion, 11 species, 10 genera and 6 families, and basal area equal to 5.14 m2.ha-1. Using the second criteria, were sampled 1,200 individuals, 13 species, 12 genders and 7 families and basal area equal 11.10 m2.ha-1. The richest families were Fabaceae and Euphorbiaceae in both surveys. The five species of greatest importance in the area using the first criterion were Aspidosperma pyrifolium, Mimosa tenuiflora, Croton blanchetianus, Piptadenia stipulacea and Jatropha mollissima. Using the second criterion were Aspidosperma pyrifolium, Mimosa tenuiflora, C. blanchetianus, P. stipulacea and Erythroxylum pungens. The floristic similarity between the plots of the phytosociological survey by the Jaccard´s index showed a high similarity between them, except for plot 15. In the natural regeneration, 169 individuals from 8 species were collected, distributed in 6 families. C. blanchetianus, M. tenuiflora and A. pyrifolium were the most abundant species, and were present in all classes. Five species present in the woody stratum were not found in the natural regeneration stratum, were Anadenanthera colubrina, Cnidoscolus quercifolius, Cynophalla flexuosa, J. mollissima and Mimosa ophthalmocentra. The similarity between both strata by the Sorensen similarity index was 0.6 with the criterion of inclusion of CAP ≥ 6 cm and of 0.7 with the criterion of CNB ≥ 9 cm.