Unravelling the drivers of seed dispersal distance in Brazilian savanna anemochoric species: The role of abiotic and biotic factors.

Abstract

Seed dispersal is a critical ecological process shaping plant recruitment and community structure. In wind-dispersed (anemochoric) seeds, seed dispersal distance depends on both abiotic (e.g. wind) and biotic (e.g. plant and seed traits) factors. Drivers of seed dispersal distance in the Southern Hemisphere remain largely unknown, particularly in ecologically and climatically unique ecosystems, such as the Brazilian savanna, where anemochoric species comprise ~30% of the flora. We addressed three questions: (1) what are the main drivers of seed dispersal distance in anemochoric species of the Brazilian savanna; (2) how do wind and plant traits independently and interactively affect seed dispersal distance; and (3) are there trade-offs or trait syndromes among dispersal-related traits in Brazilian savanna species? We used field and wind tunnel experiments to assess the roles of wind speed and traits (plant height, seed mass, seed surface area, aerodynamic group) in shaping seed dispersal distance in six species. Seed dispersal distance was primarily driven by wind speed, with additional effects from seed mass, seed area, and aerodynamic group. Unlike other ecosystems, plant height had little influence, likely related to low-stature vegetation in this region. Variations within aerodynamic groups and interactions with wind speed, especially in high-wind conditions, highlight the complexity of dispersal dynamics. Combining field and wind tunnel data, we captured both natural variability and trait-specific responses across wind conditions. As climate change alters wind regimes and fragmentation intensifies, integrating trait-based, experimental and spatial data will be essential for predicting species persistence and informing conservation in this vulnerable ecosystem.