Logging decreases the pollen dispersal distance in a low-density population of the tree Bagassa guianensis in the Brazilian Amazon

Abstract

This study investigates the distance and patterns of pollen dispersal before and after logging in a low-density population of the dioecious, insect pollinated tree species, Bagassa guianensis, in the Brazilian Amazon. All adult trees found before and after logging in a 500 ha plot were mapped and genotyped for six microsatellite loci. Seeds collected before and after logging were also sampled and genotyped. We used a categorical paternity analysis to determine seed paternity. Our results showed similar levels of pollen flow before (23%) and after logging (26%), but an increase in the mean effective pollination neighbourhood area, and a decrease in the rate of mating among relatives after logging, resulting in open pollinated seeds with lower levels of inbreeding (0.126) than before logging (0.222). We also detected changes in the mating pattern between before and after logging, a decrease in the median pollen dispersal distance and effective number of pollen donors after logging. Our results support the idea that reproductive trees should be maintained in the plot and around logged areas, using lowest levels of logging intensity to maintain pollen flow and decrease the relatedness of subsequent generations.