How effective is direct seeding to restore the functional composition of neotropical savannas?

Abstract

Species loss leads to changes in ecosystem function and services, impacting human well-being. Although biodiversity restoration is pivotal to circumvent this situation, the techniques for restoring old-growth savannas are still limited and the restoration outcomes remain unpredictable. Here, we use a trait-based approach to understand the functional outcomes of ecological restoration via direct seeding in a Brazilian savanna (cerrado, hereafter neotropical savanna). We compared the functional composition from woody and non-woody component, total biomass and biomass allocation of a restored relative to a degraded savanna (abandoned pasture) dominated by exotic grasses and a well-preserved old-growth native savanna. We found that the functional composition of restored communities was very similar to those dominated by exotic grasses, both characterized by a greater dominance of species with acquisitive traits, higher above-ground biomass, and lower investment in root biomass. In contrast, the native vegetation exhibited a dominance of conservative traits and higher investment in belowground rather than aboveground biomass. Even though the acquisitive traits in the restored savanna allow a fast aboveground biomass accumulation and soil cover, the lower belowground biomass investment in the restored savanna may limit its resistance and resilience to droughts and fires. Our findings suggest that restoration efforts in neotropical savanna should focus on fostering the establishment of slow-growing species to recover the ecosystem properties provided by the high biodiversity in neotropical savannas.