Demography of the endangered tree species Ocotea porosa (Lauraceae) along a gradient of forest disturbance in Southern Brazil

Abstract

Ocotea porosa (Ness) Barroso (Lauraceae), a typical tree of the southern Atlantic Forest in Brazil, was heavily exploited for timber in the last century. With the aim of examining the status of the remaining populations, we surveyed five forest fragments in the state of Paraná, in southern Brazil, and evaluated whether disturbances caused by selective logging and fragmentation were related to population structure of O. porosa. We assessed demographic aspects related to tree density, size hierarchy and individual allometry, correlating those parameters with fragment structure variables (fragment size, isolation and logging level). We found that, although all populations occurred in low densities (60-440 individuals ha -1), the number of adults was significantly lower in the smaller and most disturbed fragments (13 and 35 individuals ha -1, respectively). We did not detect changes in allometric relationships among individuals in the five populations studied. However, we found that populations in more heavily disturbed areas presented lower size hierarchy (i.e., less dominance of larger trees) than did those in undisturbed areas, suggesting that selective logging affects the population structure of O. porosa, possibly affecting the rates of reproduction and fecundity, which may ultimately increase the probability of local extinction.