Movimentos sazonais de vertebrados terrestres entre florestas periodicamente alagadas e de terra firme

Abstract

The flood pulse is the main factor structuring and differentiating the ecological communities of Amazonian unflooded (terra firme) and seasonally-flooded (várzea) forests as they require unique adaptations to survive the prolonged annual floods. Therefore, várzea and terra firme forests hammer out a spatio-temporal mosaic of resource availability, which may result in landscape scale seasonal movements of terrestrial vertebrates between adjacent forest types. Yet the lateral movements of terrestrial vertebrates between hydrologically distinct neighbouring forest types exhibiting staggered resource availability remains poorly understood, despite the important implications of this spatial dynamic for the ecology and conservation of forest wildlife. We examined the hypothesis of seasonal movements between two adjacent forest types at two contiguous sustainable-use forest reserves in Western Brazilian Amazonia, investigating the effects of water level, landscape and anthropogenic disturbance on the overall species richness, composition, and abundance of nine major vertebrate trophic guilds. Species richness differed in neighboring terra firme forests between the high-and low-water phases of the flood pulse and terra firme forests were more species rich than várzea forests. There were clear differences in species composition between both forest types and seasons. Generalized Linear Models showed that water level was the main factor explaining aggregate abundance of all species and three trophic guilds. Anthropogenic disturbance and geographic setting of camera trap stations, including distance to the nearest urban center, the number of residents of the nearest community, elevation and the surrounding area of várzea of each camera trap station, had a variety of effects on the terrestrial vertebrate assemblage. Overall vertebrate biomass increased with distance from the nearest urban center. Our results indicate that the persistence of viable populations of large terrestrial vertebrates adjacent to major Amazonian rivers requires large, wellconnected forest landscapes encompassing different forest types to ensure large-scale lateral movements by forest wildlife.