Effects of selective logging on the diversity and abundance of flowering and fruiting understory plants in a Central Amazonian forest

Abstract

There is much interest in ways to exploit tropical timber without greatly changing forest processes and diversity. To achieve this, it is necessary to know the maximum logging intensity that can be used and how long the forest takes to recover from logging. Because little is known about the effects of selective logging on non-timber plant species, we examined the effects of logging intensity and time after logging on the diversity and abundance of fowering and fruiting understoty plants in a Central Amazonian forest near Manaus, Brazil. Logging was carried out experimentally at varying intensities in eight 4 ha plots in 1987 and three plots in 1993. Logging intensity ranged between 14 and 45 m3/ha of extracted timber. Three plots were left as controls. Each month, from October 1996 to September 1998, we recorded the number of individuals and species of herbs, shrubs, small trees, and small palms that were flowering and fruiting in six transects per plot. We found 107 species flowering and 111 species fruiting. The abundance of flowering plants was affected by time after logging, but not by the intensity of logging. The abundance of fruiting plants was not related either to time after logging or logging intensity. Richness of flowering and fruiting plants was related to time after logging, but not to the intensity of logging. The results indicate that selective logging, at the intensities and scale analyzed, does not cause reductions in flower and fruit production by the understory community. Both quantity and quality of resources for animals are maintained and possibly even increased in logged areas, shortly after logging takes place. As the levels of reproduction in plots logged 11 years before remained close to those in controls, maintenance of the understory community does not seem to be problematical.