Aspectos da dinamica de clareira em uma floresta estacional semidecidual no municipio de Campinas, SP

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

The present paper was developed in ten natural gaps of Santa Genebra Municipal Reservation (22°49 45"S and 47°06 33"W) in Campinas, SP. For the characterization of the gaps the canopy area and opening were determined using hemispherical photographs. The shrub and tree individuais with height ? 0,50 m were sampled in the total area and in the gaps as well as in contiguous quadrats installed in each gap. , range of 3 m surrounding the gaps, all individuals with PBH (perimeter at breast height) ?15m were sampled. The floristic similarities among the gaps and its surroundings were evaluated by grouping analysis and Jaccard similarity index. The area of the gaps varied from 20,09 up to 468 m2, the small gaps predominating, explaining the greater abundance of late successional species. The families with a greater richness in the gaps were Rutaceae, Rubiaceae and Euphorbiaceae and more numerous were Rubiaceae, Euphorbiaceae and Violaceae, distinguished mainly by the high density of Coffea arabica, Hybanthus atropurpureus and Actinostemon klotschii, respectively, alI wide distributed in the forest subwood. The high number of species (105) found in the gaps reflects the importance of disturbance in the maintenance of species diversity in the studied forest. The floristic similarity among the gaps was considered low and may be related to the heterogeneity of the surrounding forest, the different regeneration sites created by the gaps, the remaining vegetation and to stochastic factors. The floristic differences among the gaps may possibly be contributing to the maintenance or to the increase of the floristic heterogeneity among sections of the forest. The methodology tested utilizing quadrats for colonizer vegetation sampling was show to be adequate since they sampled almost completely the diversity encountered in the total areas of the gaps. Floristic compositional aspects such as low similarity among gaps and abundant secondary late species were common between the two samples, that is, the total area ofthe gap and the parcels. The use of hemispheric photographs was demonstrated to be a practical, fast and effective method which allows a more precise determination of the gap area since it considers the perimeter irregularities and the calculation of canopy opening allowing a more precise descriptrion of the environmental conditions of the gaps

ASSUNTO(S)

ecologia vegetal sucessão ecologica florestas tropicais

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