Allometric relationships in Psychotria suterella Müll. Arg. (Rubiaceae) in a fragmented landscape of Atlantic Forest

Abstract

The allometric relationship between diameter and height was studied in populations of Psychotria suterella, a common understory species of the Atlantic Forest of southeastern Brazil, in natural situations of different density and luminosity. Nine populations were sampled including three areas of continuous forest, three connected fragments and three isolated fragments, all within a fragmented Atlantic Forest landscape. In conditions of higher density and light availability, young individuals possessed a greater increase in height per unit of diameter than adult individuals. In all the varying conditions of light and density, the allometric pattern of young growth did not change. On the other hand, adult individuals exhibited a greater increase in height in high-density conditions. There were differences among allometric coefficients of some of the populations. In fragments where the canopy openness was greater, the population possessed individuals with greater height. On a smaller scale, light and density affected the allometric relationship of individuals. On a larger scale, populations with a low density of individuals, and which were subjected to greater luminosity, varied greatly in growth form.