Structure and floristic diversity of remnant semideciduous forest under varying levels of disturbance

Abstract

The perturbation of Neotropical forests generates large disturbances in biological communities. The species that suffer least from the resulting habitat fragmentation are the pioneers, because they possess greater ability to inhabit disturbed environments. Therefore, it is expected that species diversity will be greater in areas subjected to intermediate disturbance, such as the opening of gaps, because a large number of pioneer species will develop and coexist with species of more advanced successional stages. This study aimed to compare two forest remnants that differed in size and disturbance intensity, in order to determine the effects of disturbances on species diversity and the size ratios of individual trees. This was accomplished with comparative analyses of diversity, richness and diameter ratios obtained for 10 plots at two semideciduous forest sites. We recorded a total of 85 species, of which 70 were in the private nature reserve Fazenda Santa Maria, 58 were in Iguaçu National Park, and 43 were at both sites. Diversity was greater in the more disturbed remaining forest, because this area showed higher species richness, which is in accordance with some premises of the intermediate disturbance theory. There was also an increase in the number of pioneer individuals, and the less disturbed area showed individuals with larger diameters, which is likely attribu table to the removal of large individuals from the more disturbed area during the anthropogenic process of forest modification.

Caracterização Da Produção De Serapilheira E Da Chuva De Sementes Em Uma Reserva De Floresta Estacional Semidecidual, Paraná

“…Os valores de densidade absoluta de 2.033,29 sementes m -2 e de riqueza de espécies (S=79), registrados em um ano foram superiores aos obtidos em outros estudos com chuva de sementes realizados em fragmentos de Florestas Estacionais (PENHALBER; MANTOVANI, 1997;GROMBONE-GUARATINI;RODRIGUES, 2002;ARAUJO et al, 2004;CAMPOS et al, 2009) (Tabela 2). Os diferentes valores ocorreram devido às diferentes características, como diferenças florísticas nas distribuições regionais das espécies e diferentes estágios sucessionais dos fragmentos florestais comparados.…”

“…A chuva de sementes representa chegada de diásporos, ou seja, sementes, frutos e esporos, de diferentes espécies a um ambiente, e o posterior estabelecimento desses diásporos direcionará o desenvolvimento sucessional e as mudanças na comunidade (HOWE;SMALLWOOD, 1982), definindo, portanto, o modelo para o futuro padrão de regeneração e recrutamento da população (LOISELLE et al, 1996). Portanto, estudos sobre a chuva de sementes fornecem informações sobre a abundância e riqueza das espécies que estão chegando a um local (GROMBONE-GUARATINI;RODRIGUES, 2002).…”

Structure and Spatial Pattern of Vegetation in a Fragment of Atlantic Forest

“…In relation to the species distribution patterns in the area, tropical forests generally present high spatial and temporal heterogeneity, which strongly influences species distribution patterns (Gris et al, 2014). In tropical ombrophilous forests, restricted seed dispersal around the maternal plant may be a preponderant factor for the spatial pattern found for species with aggregate distribution (Fajardo et al, 2015).…”

“…Degradation processes resulting from natural events or human activities entail the fragmentation of these environments (Gris et al, 2014;Zanini et al, 2014), reflecting directly on the landscape structure, as well as results in different levels and degrees of disturbance, implying variation in the frequency and abundance of pioneer species and vegetation patterns (Lasky et al, 2013). In view of the above, the objective of this work was to analyze the species diversity, the horizontal structure and the spatial pattern of a fragment of the Atlantic Forest located in Dois Irmãos State Park, Recife, Pernambuco, Brazil.…”

Efeito alelopático de Leucaena leucocephala e Hovenia dulcis sobre germinação de Mimosa bimucronata e Peltophorum dubium

“…As coletas das espécies do presente estudo foram coletadas em área de Floresta Estacional Semidecidual. Neste fragmento observou-se grande representação de indivíduos de espécies nativas, como M. bimucronata e P. dubium (Gris et al 2014) assim como de espécies exóticas, destacando-se a L. leucocephala e H. dulcis, tornando necessária a investigação do potencial alelopático destas espécies (exóticas), no sentido de verificar se esta é uma possível estratégia que contribui para o estabelecimento dessas populações, a qual pode impedir o estabelecimento de espécies nativas.…”