Structure of a population of Esenbeckia leiocarpa Engl. (Rutaceae) in a seasonal semidecidual forest in southeast Brazil / Estrutura de uma população de Esenbeckia leiocarpa Engl. (Rutaceae) numa floresta estacional semidecidua no Sudeste do Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

The present study investigated the structure of a population of Esenbeckia leiocarpa, popularly known as ?guarantã?, a canopy species, not pioneer and common in the region studied. The study was carried out in an area of 3.2 ha of seasonal semi-deciduous forest in Campinas ? SP. We randomly installed 50 plots of 10 x 10 m, in a total of 0.5 ha. In each 100 m2 plot we sampled all the individuals of this specie, except from seedlings, that were sampled in 50 sub-plots of 1 m2, randomly chosen among the vertices of each 100 m2 plot. For all the individuals we registered the diameter of the trunk at ground level, the presence of cotyledons, branches, reproductive activity, budding and infestation by lianas. We identified six ontogenetic stages within this population: seedlings, juvenile 1, juvenile 2, immature, adult and senile. The branching pattern presented by E. leiocarpa was similar to the architectural model of Massart that is well adapted to the dimly lit conditions predominant in the interior of forests, where the guarantã initiates its development. There was little size overlap between the ontogenetic stages, indicating that the height and diameter may help in the determination of the ontogenetic stages and that certain structures such as the flowers and fruits can only be found after the plant has reached a minimum height. The initial stages of seedling and juvenile 2 presented less increase in diameter per increase in height, while the opposite occurred in the later stages. The greater investment in height during the first ontogenetic stages allows the individuals to rapidly reach the good conditions of light of the forest canopy. These data indicate that E. leiocarpa presents a growth pattern similar to other common species of the humid tropical forests and the temperate forests that share some aspects of its life history, such as the position in the forest?s canopy and the successional status. The seedlings density was quite high, presenting a spatial pattern grouped close to the adult individuals. The seedlings presented high rates of mortality, mainly in the sites with closed canopy. The level of aggregation decreases during the ontogeny and in the latest ontogenetic stages the plants presented random spatial patterns in all of the distance classes. Different ontogenetic stages were correlated in space, indicating that the dispersion of the seeds is limited or that the environmental favorability may be kept in the different ontogenetic stages. The size and ontogenetic structures presented continuous distributions, with relatively few juvenile and immature individuals. These results, together with other characteristics such as the high seedling mortality, the moderate fertility, the spatial distribution that is not related to the openness of the canopy and the different architectures ? considering the height of the morphologic inversion point ? observed, indicate that E. leiocarpa is a specie with characteristics both of tolerance and of intolerance to shadows. Although more studies are needed to confirm how these observed characteristics vary in time and space, this relative ecological flexibility allows this specie to occupy different environments inside the Forest, thus being E. leiocarpa a good option for the recuperation of degraded areas

ASSUNTO(S)

alometria esenbeckia leiocarpa plants ontogeny vegetal morphology plantas - ontogenia morfologia vegetal allometry

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