Floristica, fitossociologia e caracterização sucessional em uma floresta estacional semidecidual : Mata da Virginia,Matão, SP

AUTOR(ES)
DATA DE PUBLICAÇÃO

1997

RESUMO

This work was developed in the mata da Virgínia, with 2.072,64ha, being one of the biggest remnants of semidecidual stational forest of the São Paulo state, situated in a farmer named Cambuhy between the cities of Matão and Tabatinga ( 48°. 30 W e 21°.35 5). Different physiognomy were identified in the forest from the analysis of aerial photos and some discussions were made about the influence of abiotic (soil, topography, drainage system, etc..) or antropic factors on it. From the results it was done the phytosociological study of the shrub and tree layers of two areas of the Mata da Virgínia with different pertubation degree by anthropogenetic interferences (one area considered preserved and another pertubed), besides the floristic survey through walkings by the forest to collect reproductive botanic material of shrub and tree species.According Koppen the local climate was classified as CWa (humid subtropical). The soil of the two ampled areas in the phytosociological survey was identified as Red YelIow Podzolic. The floristical survey was made from April 95 to May 96 and the collects were concentrated in the perimeter of the forest and in the margins of the two roads that cross it, with an extension of around 30km. Observations were made about the locaIs of the occurence of the species, in border areas, forest interior or riverine areas. It was used the contiguous plot method for the phytosociological survey of the tree layer, with the location of 36 plots of 15 X 15m in each one of the study areas, totalizing 1,72ha of sampled area. The sampling criteria used in the tree layer was of PHB (perimeter at breast height) ? 15cm. In each of the studied areas 10 of these 36 parcels were sorted for the phytosociological survey of the shrub layer, totalizing 0,45ha of sampled area where alI the species with PHB <15,Ocm were sampled. In the floristic survey 194 species were sampled, belonging to 129 genera and 54 families. The greater number of these are early-successional species (pionner and early secondary). The majority of the pioneer species were found in border areas of the mata da Virgínia and the great parcel of the secondary species were found in border areas as well as in the forest interior. The families of higher floristic richness were Myrtaceae, Rubiaceae, Euphorbiaceae ,Rutaceae, Fabaceae, Caesalpiniceae, Piperaceae and Mimosaceae. In the area that was considered preserved (Area 01), the late secondary species showed the double of the individuals and higher importance value than the early secondary, and the pioneers had inexpressive participation with only 4 individuals sampled. The families that appeared with higher index of importance value in the tree layer were Rutaceae, Apocynaceae and Meliaceae, being Aspidosperma polyneuron, Galipea multiflora, Astronium graveolens and Metrodorea nigra the most important species of the survey. In the shrub layer Euphorbiceae and Meliaceae were the families that appeared with more portion of IV!, and the species with bigger values for this parameter were Actinostemon communis, Metradorea nigra and Galipea multiflora, being the first one that apeared as the dominant specie, with 56,35% of the total IVI obtained, nine times higher than the second more important specie. In the considered pertubed area (Area 02) the early successional species (pioneers and early secondary) prevailed on the late secondary as in number of individuals as in importance value. Rutaceae, Euphorbiaceae and Apocynaceae were the families that apeared with higher IVI in the tree layer. The species that had higher values in this parameter were: Metrodorea nigra, Crotonjloribundus, Aspidosperma polyneuron and Acacia polyphylla. For the shrub layer the families and species that obtained higher IVI values were as well: Rutaceae, Euphorbiaceae and Meliceae, Metradorea nigra,Actinostemon communis, Galipea multiflora and Piper amalago.In the tree layer the Shannon s index was H =3,07 and H = 3,00 for the Areas 01 and 02 respectively. Taking in consideration the whole survey (Areas 01 and Area 02) the obtained diversity was H =3,24. This value can be found within the existing diversity in the stational semidecidual forests in the state of São Paulo, but it was considered low in this study and can be related with the historic of the forest, mainly the selective logging, performed for a period higher than 50 years and only recently interrupted. The results of the shrubby layer strengthened this hypothesis; the diversity found in the general survey (Areas 01 and Area 02) was of H =1,59, lower than of which found in the same layer, in others remants of estacional semedecidual forest. However, in the shrubby layer there were differences in the diversity between areas, with the Area 01 giving H =1,00 and Area 02, H =2,13

ASSUNTO(S)

dinamica de vegetação florestas tropicais ecologia florestal

ACESSO AO ARTIGO

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