Estrutura populacional do cambará (Vochysia divergens Pohl, Vochysiaceae), espécie monodominante em floresta inundável no pantanal mato-grossense

Abstract

Vochysia divergens Pohl (cambará) occurs in dense monodominant stands in the Pantanal, called cambarazal. The present study, carried out in the RPPN SESC Pantanal (Nature Patrimony Private Reserve- NPPR), Barão de Melgaço, Mato Grosso (Brazil) aimed mainly at characterizing the population of V. divergens along a hydro-topographical gradient with respect to its size (diameter and height) and age structure and still verifying the relations between population density and basal area with edaphic variables (pH, Al, organic carbon and clay content). The study was carried out in four plots (P1 to P4) of one hectare each (100m × 100m) established within a cambarazal. For this, all individuals of cambará with CBH (Circumference at Breast Height) ≥ 5 cm were sampled, their perimeter measured and height estimated to derive structural parameters. In total, 656 individuals of V. divergens were sampled in the four plots. Dominance values greater than 50% were found in the plots P2, P3 and P4, characterizing the monodominance of cambará. The plot with the oldest population of cambará (156 years), located in the center of the cambarazal (P3), seems to function as "core" area of spreading of cambará towards adjacent areas, P1 (48 years), P2 (100 years) and P4 (102 years). The successional development of this monodominant forest seems to be associated with the increased number of tall individuals of cambará (> 20m) and of intermediate-size diameter (43,8cm a 51,1cm). A study case assessing the relation between population parameters and edaphic variables was conducted in the oldest plot of cambará (P3). This study showed that the more acid the soils are, the higher the density and dominance of the cambará become. The example of cambará, illustrated in this work, showed that seasonally flooded forest formations in the Pantanal are subjected to intense population dynamics, related to expansion/retraction processes of population.