Limited contribution from soil seedbanks and high spatial turnover characterize early plant communities in overgrazed tropical pastures

Soil seed banks play an important role in post-disturbance recovery of plant communities, but many studies focus on a snapshot of seed banks at single sites in time and space, limiting the ability to assess how seed banks contribute to early plant community assembly. To understand how seed banks influence regenerating plant communities, it is important to assess what proportion of seeds in the seed bank can establish and survive in natural conditions. Here, we investigated the composition of tropical seed banks on plant emergence and its relationship to the composition and dominance of plant taxa after one year of natural regeneration at ten experimental plots on cattle pastures in southeastern Brazil. We specifically evaluated the compositional and spatial turnover of plant communities from seed bank emergence to one-year old communities. We found little compositional overlap and a shift from herbaceous to woody dominance between the communities emerging from seed banks compared to those occurring after one year. There was also a high – often complete – turnover of plant taxa across study sites indicating strong spatial heterogeneity in dispersal dynamics and environmental filtering that control local plant community assembly. Our findings show that although the soil seed bank retains a diverse assemblage of species, less than one-third of seed bank taxa were also recorded in plant communities after one year, highlighting the limited correspondence between seed bank composition and early stages of forest regeneration. Overall, our results emphasize the importance of dispersal processes and post-emergence environmental filtering in shaping early successional trajectories. Restoration strategies in degraded tropical pastures should prioritize enhancing seed input and establishment conditions rather than relying solely on naturally occurring soil seed banks.