Direct and indirect effects of landscape, forest patch and sampling site predictors on biotic interaction and seed process

Understanding the response of seed rain and seed bank to landscape changes is critical for maintaining the forest remnants integrity and the potential for natural regeneration in abandoned lands. Ecological research typically focuses on direct responses of these seed processes (i.e., seed rain and seed bank), without considering the relationship between them or the indirect impact of landscape changes on these processes via its influence on seed dispersers and seed predation. Here, we employ structuring equation modeling to quantify the direct and indirect effects of landscape structure and biotic interaction on bird-dispersed seed rain and seed banks in the Atlantic Forest. We conducted the study in 20 highly fragmented landscapes. Our study shows that lower seed disperser, seed rain and seed bank abundances, as well as higher seed predation rates will be found in a landscape context with higher percentage of pasture, isolated forest fragments and in matrices far from forest edge. The indirect effect of landscape change was related to the negative influence of seed predation rates on the seed bank abundance. Based on our results, we recommend managing the landscapes trying to increase the connectivity among the forest remnants and reduce the percentage of pasture, in order to improve the seed dispersal and decrease the seed predation rates. In addition, it is essential that management plans evaluate these processes as a whole to accelerate forest recovery due to the complex relationships associated with seed rain and seed bank. Graphical abstract: Conceptual model highlighting the spatial context effects on biotic interaction (seed dispersers and predation) and seed processes (seed rain and seed bank). A At sampling local level, the seed rain and the seed predators have the opposite response to the distance to the forest edge. In addition, the seed predators vary according to the type of land cover/use. The seed predation inside the forest is lower than the outside. The highest predation was in coffee plantations. B At a landscape level, the percentage of pasture in the surrounding landscape has an inverse effect on seed predation, seed bank, and seed rain, being positive for seed predation, but negative for the seed bank and seed rain. Otherwise, the percentage of coffee plantations in the landscape has a positive effect on seed dispersers. [Figure not available: see fulltext.]