Igapó seed patches: a potentially key resource for terrestrial vertebrates in a seasonally flooded forest of central Amazonia

Abstract

Abstract In Amazonian igapó forests (seasonally flooded forests on blackwater river margins), the end of the annual flood pulse results in the formation of extensive mat-like seed patches. The seeds in these patches then germinate, forming a dense, highly heterogeneous, assemblage. Animal–plant interactions in these areas, as well as the influence that the patches have on the occurrence of herbivorous vertebrates, remain almost completely unstudied. Using camera traps in areas with and without seed/seedling patches, we tested the relationship between these seed accumulation sites and the presence of bird and mammal species. At the micro-scale (between treatments), vertebrate occurrence was not related to patch presence. At the larger scale (local), distance from adjacent upland (terra firme) forest and seed patch size were correlated with vertebrate distribution. The widespread occurrence of terrestrially active birds and mammals throughout igapó forests, not just where food resource densities were high, seems to be a compromise strategy between exploring the area to select the most favourable food items, and minimizing the risk of being predated when spending extended time foraging at the concentrated food sources represented by the seed patches. Our results underline the potential importance of igapó forests as a key habitat for a variety of terrestrial terra firme taxa, as well as emphasize the dynamic nature of this forest type, and should encourage further studies of this habitat and resource availability system.