Successional processes in agricultural mosaics in the eastern Amazon

Most tropical landscapes are mainly composed of dynamic mosaics involving multiple land uses. Different histories of land use management can lead to different successional paths. The aim of this study was to determine if there is a successional floristic gradient related to land use types and how these gradients change across three rural mosaics in Eastern Amazon. We also investigated what are the indicator species across mosaics and land use types and how they change through succession. Five sampling points were established in nine family farms at each mosaic. A detrended correspondence analysis was used to reveal the successional gradient. A multivariate regression tree was used to analyze differences in floristic composition between mosaics and land uses. Floristic similarity between land uses formed successional gradient at the mosaics, in which agricultural land uses represent the early stages of secondary succession and forests represent more advanced stages. Total number of species and total number of shade-tolerant species were correlated with advanced successional stages in all mosaics, but pioneer trees were also correlated with advanced stages in fragmented mosaics. Each mosaic had a distinct successional series due to different management approaches. Where the matrix was mainly composed of forest fragments and the human intervention period was shorter, land use types were more similar to one another as they were grouped into fewer successional stages. Thus, the floristic similarity between land use types appears as an indicator of successional advancement across the mosaics and help determine the regenerative capacity of those areas.