Tree populations structure and dynamics of a semideciduous seazonal forest fragment in the Piracicaba region, São Paulo state, BrazilFragmentation of tropical forests associated with anthropogenic disturbance can result in a loss of tree species and floristic composition change throughout the time in a forest fragment. To gather quantitative data regarding this hypothesis, this study was conducted in a 9.5 ha semideciduous seazonal forest fragment located in Piracicaba region, São Paulo state, Brazil. This fragment is named "Mata do Pomar", where two fires occurred in the recent past. In this fragment, recruitment, mortality and populational change of tree species were obtained in 4-year period (1991 and 1995). Different patterns of recruitment, mortality and populational change were found among tree species and ecological groups. The ten species more abundant in 1991 (class 1 -⊕ 15 individuals/ha ) presented 79.9% of recruitament, against only 7.5% and 9.0% of recruitment presented by density classes 2 (5.2 to 13.8 individuals/ ha) and 3 (1.7 and 3.4 individuals/ha), respectively. In particular, the three most abundant tree species in 1991, Bauhinia forficata, Aloysia virgata and Urera baccifera, all pioneer species, and Croton floribundus, an opportunistic species, were responsible for 75% of recruitment.Coupled with the high recruitment, these species also had low mortality, which resulted in a pronunciated population increasing. In the two lower density classes, 2 and 3, beyond the low recruitment, the pioneer and the opportunistic species presented 74.2% of recruitment. These last groups also presented a greater density gain than shade-tolerant canopy species and shade-tolerant understory species in the density classes 2 and 3. Beyond these results were also done a comparative analysis of this fragment with a fragment of same size ("Santa Rita" fragment -9.5 ha) and a fragment of 86 ha ("Capuava" fragment), both located in Piracicaba region.The "Mata do Pomar" fragment presents less of the half of tree species than "Santa Rita" and "Capuava" fragments, although with the same size of "Santa Rita" fragment. Further, the four most abundant tree species in the "Mata do Pomar" fragment, B. forficata, A. virgata, U. baccifera and T. micrantha are responsible for 62% of individuals, whereas the four most abundant tree species in "Santa Rita" and "Capuava" fragments are responsibles for only 30.6% and 23.2% of individuals, respectively, indicating a high local dominance in the "Mata do Pomar" fragment.This study demonstrates that strategies of conservation biodirversity in semideciduous seazonal forest fragments in the São Paulo state should consider the anthropogenic disturbance in the identification of conservation priorities.

No abstract

No abstract

O Programa Bolsa Floresta implementa uma série de atividades prioneiras no campo da conservação ambiental e desenvolvimento sustentável na Amazônia. Sua concepção se insere no contexto das mudanças climáticas globais e de redução do desmatamento, com especial ênfase para as comunidades tradicionais da "Amazônia profunda". Este artigo descreve o conceito e a estratégia de implementação do Programa, com uma ênfase especial para as ações de saúde. Primeiro, é apresentado o contexto no qual foi concebido. Depois, apresentam-se o conceito, a estrutura e os resultados obtidos até setembro de 2008. Na seqüência, indicam-se o diagnóstico e as ações relacionadas com saúde pública. Finalmente, abordam-se o significado histórico e as perspectivas desse Programa.

No abstract

No abstract

No abstract

Forest structure and tree species composition were studied in four Atlantic seasonal forest fragments ranging from 0.7 to 220 ha, isolated for more than a century in southeastern Brazil. Four physiognomic units were recognized within these fragments: (1) low forest, (2) bamboo forest, (3) high forest, and (4) mature forest. Tree density, basal area, and species diversity (Shannon‐Wiener index) increased from low forest to bamboo forest to high forest to mature forest. Liana cover was highest in low forest. Gap‐opportunistic species were the dominant ecological group in low forest, bamboo forest, and high forest, while shade tolerant canopy species formed the dominant group in mature forest. These structural and compositional features formed a gradient of forest development from the least developed low and bamboo forests to the most developed mature forest. Low forest is hypothesized to be in a stage of arrested succession and high forest a stage of degraded forest. A conceptual model is suggested to explain how these physiognomic units may be related to one another. Although these fragments were covered mainly by high and low forests and thus had a degraded structure, species diversity remained high in all of them. Fragments thus may undergo degradation long after isolation, even when they have been protected from human disturbance for a considerable period. Nonetheless, they also preserve important samples of local and regional floristic diversity for a long time after isolation.