Análise da vegetação arbórea e conservação na Reserva Florestal da Cidade Universitária "Armando de Salles Oliveira", São Paulo, SP / Analysis of arboreal vegetation and conservation at the Forest Reserve of the Cidade Universitária "Armando de Salles Oliveira", São Paulo, SP, Brazil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2002

RESUMO

This work analyses the structure and dynamics, at several spatial and temporal scales, of the arboreal community in the Reserve of the Cidade Universitária "Armando de Salles Oliveira" (CUASO) (23º33’ S, 46º43’ W), São Paulo, SP. Based on these data, management actions are suggested, aiming at the conservation of the arboreal community at the site. The Reserve is a secondary forest patch with an area of approximately 10 ha. We describe the 1930-1994 changes in landscape structure in the surroundings (330 ha) of the Reserve, showing the urbanization process in the region. As a consequence, the area covered by grasslands was reduced and the area covered by buildings increased. Forested areas declined and recovered partially afterwards. Roughly 40% of the Reserve encompasses vegetation more than 70 years old and 22% are areas less than 27 years old, located near the edges. We mapped, measured the dbh and identified all 1157 trees with dbh >25 cm in 8.58 ha (Area 1, the total area of the Reserve excluding the lake and a 1.5 ha-area dominated by Eucalyptus sp.) and all 1270 trees with dbh >9.5 cm in 2 ha (Area 2) in the Reserve. In Area 1 we found 91 species (10.9% being exotic) and a Shannon index H’ of 3,34 nats/ind., with 33.7% of the species being represented by only one individual. Exotic species and introduced natives were generally restricted to the regions near the edge, with the exception of Archontophoenix cunninghamiana. No place inside the Reserve is more than 110 m away from the edge, due to the size and shape of the Reserve. Correspondence analyses showed important variation of the community (dbh >25 cm) with distance to the edge up to 50 m, but suggest that age of vegetation is more important in defining the composition of the community. In Area 2 we found 103 species (10.7% exotic) and H’ = 3.54 nats/ind. We analysed structural and compositional changes of the arboreal community (dbh ≥ 15.9 cm) between 1992 and 1997 within a 100 x 50 m plot. Density and basal area of the total community increased considerably in the period; species diversity and evenness remained almost the same, but diversity and evenness of native species decreased. In a 2.1 ha area inside the Reserve, A. cunninghamiana was the species with the highest density among trees with DBH ≥ 9.5 cm, with 305 individuals (22.5% of total). The species shows preference for establishment in shady sites. The size structure analysis indicates a future increase in the relative density of the species. Two surveys with a 2.5 years interval (DBH ≥ 9.5 cm) showed the death of three of the initial 154 individuals and the recruitment of 89 more, leading to a population growth of 19.4 %.year-1, a very high rate. CUAKIA, a gap model derived from KIAMBRAM, was parameterized to simulate the present state of the forest in the Reserve The model predicted an initial sucessional phase dominated by Piptadenia gonoacantha, followed by a phase dominated by Croton floribundus and Alchornea spp. and, later, by Ficus insipida and other shade-tolerant and long-living canopy species. The spatial distribution of trees was analysed using the L (modification of Ripley’s K) and g functions, in their univariate and bivariate forms. The total pool of individuals with dbh >25 cm showed uniform distribution at small scales (r <6 m) and clumped distribution at bigger scales (17 m 25 cm were used to divide the Reserve into areas covered with relatively homogeneous vegetation. Correspondence analysis was used to ordinate circular plots (r = 10 m) laid out on a regular 10 m-interval grid. Scores of each plot were mapped and this mapping was used to define nine management zones inside the Reserve. One of the zones is almost exclusively occupied by Eucalyptus sp.. Others are dominated by exotics or trees which were planted in the Reserve. We suggest the introduction of native species and the control of exotics, especially A. cunninghamiana, inside the Reserve and in its surroundings.

ASSUNTO(S)

floresta tropical biological conservation spatial ecology conservação biológica ecologia espacial tropical forest

ACESSO AO ARTIGO

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