A functional view of seed limitations across a fragmented tropical forest

Abstract

Most of the critical dynamics of forest regeneration occur at the earliest life history stages (seeds and seedlings), which affect plant recruitment. Recruitment limitation occurs when seeds do not arrive to the available places in the forest (seed limitation, including source and dispersal limitation), or do not find adequate conditions for seedling emergence and growth (establishment limitation). Thus, recruitment limitation affects forest regeneration patterns, driving the dynamics and composition of forest communities. The level of recruitment limitation is affected by environmental fragmentation, ecological disturbance, vegetation type, and factors related to climate, among others. Our proposal aims to investigate the drivers of seed limitation (source and dispersal limitations) related to seed traits (dispersal mode, seed size) and ecological aspects of the species (successional status, wood density) across remnants of a fragmented tropical hotspot: the Atlantic Forest. We are investigating the patterns of seed rain across the Atlantic Forest, from South to Northeast Brazil, by compiling data from previous studies (articles, thesis and dissertations) obtained through contact with the responsible researchers combined with new data collected by our team. The goal of the proposed research internship abroad is to learn new quantitative approaches for analyzing this large database using a macroecological approach. We shall calculate seed, source, and dispersal limitation and contrast these variables as a function of vegetation type, ecological status and functional traits of the species found in the seed rain. We predict that dispersal of late successional species - correlated with a larger seed size - will be more limited compared to early successional species, and that zoochoric species will display extensive dispersal limitation due the loss of dispersal agents in the fragmented landscape. (AU)