Estrutura populacional e padrão de distribuição espacial da espécie (Carapa guiattensis Aubl. Meliaceae (andiroba) em área de várzea na floresta nacional de Caxiuanã, município de Melgaço, Pará.

Abstract

The study of the structure and pattem of spatial distributions of individuais inside of a population are basic steps for the elaboration of plans of handling in sustainable bases. This work had as objective to study the structure, pattem of spatial distribution of the individuais of a population of Carapa guianensis Aubl.. species of the botanical family Meliaceae and still to verify existing simple correlation between the abundance of individuais with soil bulk density. and soil levei in a long one of the floodplain ecosystems. The study was carried through in the bay of Caxiuanã. Anapú nver (approx 1047"S. 51025'W) in the National Forest of Caxiuanã. Melgaço. Pará. In the survey of the population had been demarcated eight plots of 10 m x 500 m. totalizing an area of 4 ha in the long one of the environmental gradient fonned by the floodplain area in direction the fírm land forest. It was take 800 samples to calculate soil bulk density. The survey of the levei of the land was lead to each 10 m to the long one of the plots until the 500 meters of distance of the edge of the river. For each plot it was established umts with 10 m x 50 m, where it had been collected scores of ali the individuais with bigger DAP of 30 cm. In each parcel had been delimited lesser units of form that they were juxtaposed. The units had followed the sizes of 10 m x 20 m where individuais with DAP between 10 and 30 cm. umts of 10 m x 10 m for the individuais with DAP between 2 cm and 10 cm and in the units of 5 m x 5 m for the individuais with lesser DAP of 2 cm. The distribution of the individuais varied in the different classes of size, reaching the two extremities of uniformity and aggregation of the individuais. The population presented itself steady. or either. many individuais in the lesser classrooms and few in the classrooms biggest. The abundance of individuais concentrated basically until the 300 meters of distance of the edge of the river. The association between the changeable soil density, soil levei, and abundance of individuais, in general demonstrated a negative correlation indicating that the high values found for one variable imply in low values for the other one.

The alterations in the abundance of the individuais in time and space are recurrent of physical and biological factors acting m different developing stage of the plants, and therefore the maintenance of a population in the environment is guaranteed by the processes of germination of seeds and recruitment of seedling. The objective of this work was to study the structure and pattems of spatial distributions of the adult and young individuais of C. guianensis Aubl. population. in a floodplam at Caxiuanã National Forest. The study was lead in the bay one of Caxiuanã. Anapú river (aprox. 1047'S, 5 l025'W). The individuais had been showed in 8 plots of 10 m x 500 m made use approximately 360° W. in the direction edge of the river to the fírm earth. For each plot had established 10 units of 10 m x 50 m, where they had been collected ali of individuais with bigger DAP of 30 cm. In each sub plot had been a dehmited httle unit of form that they vvere juxtaposed. The units had followed the sizes of 10 m x 20 m where individuais with DAP between 10 and 30 cm, units with 10 m x 10 m had been measured individuais with DAP between 2 and 10 cm and in the units with 5 m x 5 m individuais had been measured individuais with lesser DAP of 2 cm. The population presented pattem of dispersion tending grouping (Id = 3,4764). The structure of population presents in the form of inverted J. characterized by a high number of young and low number of adult individuais suggesting that the population assumes a dynamic pattem balance.

The populations generally are distributed throughout the complex gradients in the form of binomials curves, with the densities vaning in accordance with its optimum environment conditions In this point of view. the analysis of correlation with environmental vanables can expiam the pattems of distribution of individuais inside of a conimunit>-. The objective of this work was to identiíy the possible relations of abundance of individuais with the topographical gradient and soil bulk density in a Carapa guianenis Aubl. populations throughout a floodplain ecosystem in the bay of Caxiuanã. Anapú river (aprox. 1 47 S, 51 25 W) at Caxiuanã Nacional Forest. In the survey of the population had been demarcated 8 plots with 10 in x 500 m. totalizing an area of 4 ha to the long one of the environmental gradient formed by the floodplain area in direction the earth land forest. For calculation soil bulk density was collected a total of 800 samples. The survey of the levei of the land was lead to each 10 m to the long the plots until the 500 meters of distance the edge of the river. The results had demonstrated that in the general, the abundance of individuais concentrates nearest edge the river. When the topographical gradient mcreases the soil bulk density decreases. assuming that the species prefers environments lowest than the areas with plateaus formation (r = -0,124, p<0,05). There are a correlation between the soil topographic levei and soil bulk density. When mcreases the soils topographic levei it soil bulk density decreases in a little vanation (r = -0,226, p< 0.01). In general, these results were estimated with the distances of 50 and 100 meters from the edge of the river, where to the others distances the correlation were not signifícant.