Levantamento floristico e fitossociologico da floresta estacional semidecidual do Jardim Botanico Municipal de Bauru, São Paulo

AUTOR(ES)
DATA DE PUBLICAÇÃO

2000

RESUMO

A floristics and phytosociologycaI survey was developed at Jardim Botânico MunicipaI de Bauru (JBMB), São Paulo state (220 20 S e 490 00 W), a 321 hectare urban reserve, in a fragment of tropical semideciduous forest, surrounded by a larger fragment, defined as forested savanna. The climate was defined, according to Kõppen s classification, as mesothermic, with dry winters and rainy summers. The hydric balance demonstrated the existence of a soil hydric deficit during the winter. The soil, a dry red latossol, sandy phase, was analysed chemically, physically and morphologically, from trenches opened in the forest and in the forested savanna. Only the forest superficial horizons were considered eutrophic, whereas the other horizons, even the superficial ones found in the forested savanna, were considered distrophic. The floristic survey was based on samples of the two phytocenoses. Plots of 100m2, disposed in blocks, were used for the phytosociological study. Minimum height 1,5m and minimum fuste 1,3m were the criteria for inclusion of individuals. Only woody individuals were considered. The total area sampled was of 0,26ha. The floristic list enumerated a total of 192 species in the tropical semideciduous forest in 51 families, and a partiaI floristic survey ofthe forested savanna gathered 138 species in 52 families. Analysing the successional categories of the ten most numerous populations at the JBMB, i.e., 1.578 individuals (81,04%) ofthe total sampled, it was verified that 5,01% ofthe individuaIs sampled belonged to the group of the pioneers, 32,57% to the group of the initiaI secondaries and 43,41 % to the group of the late secondaries. From this group of sampled individuaIs, 19,01% could not be classified regarding the successionaI category. Studying the dispersion syndrome presented by sampled individuals, it was verified that 72,24% of the individuals presented zoocoric dispersion syndrome, 12,29% anemocoric and 0,95% autocoric. From this total, 15 individuals, or 0,95%, could not be classified regarding the dispersion syndrome. The richest families inside the small parts studied were: Rubiaceae, Myrtaceae, Fabaceae, Caesalpiniaceae e Mimosaceae. The studied vegetation presented low floristic similarity when compared according to the Jaccard index of similarity (ISj), with other fifteen areas located in the states of São Paulo, Minas Gerais and Mato Grosso. However, it was verified a bigger similarity among forest located in the central region of the state, coinciding with the Ocidental Plateau and Basalt Cuestas, corroborating others authors. The floristic diversity was defined according to the Shannon- W eaver index (R ), reaching the value of 3,79. Such value places the studied forest fragment among the ones with the widest tropical semideciduous forest diversity in Sao Paulo State. Analysing the rare species index, one could observed that it reached of 23,57%, a percentage lower than the one found in some phytosociological studies in the state of São Paulo. The ten most important, according to importance value (IV), in decreasing order, were: Ocotea pulchella (21,88%), Protium heptaphyllum (20,57%), Copaifera langsdoffii (17,00%), Cupania vernalis (10,53%), Vochysia tucanorum (6,92%), Aspidosperma cy/indrocarpum (6,75%) e Myrcia tomentosa (6,59%). The dead individuais represented 16,59% of the importance value

ASSUNTO(S)

florestas tropicais ecologia vegetal comunidades vegetais

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