The Interplay Between Fire and Microhabitat Cover Drives Seed Removal in Gallery Forests in the Brazilian Cerrado

Abstract

Fire may have distinct effects on the fauna inhabiting savannas and forests, because the former have evolved under occasional occurrence of fire, while natural caused fire tends to be rare in tropical forests. Therefore, fires may be particularly influential to plant–animal interactions in forests. We investigated the effects of wildfires on microhabitat cover and post-dispersal seed removal in gallery forests immersed in Brazilian Cerrado (savanna) landscapes. With the aid of selective exclosures, we measured the relative contribution of ants and vertebrates to the removal of seeds of three plant species varying in consumption constraints (toxicity, size). Fire increased removal of small seeds by ants, while decreasing seed removal by vertebrates, regardless of seed palatability. Vertebrates removed more seeds from covered microhabitats, while the opposite happened for ants. Larger seeds were less removed than smaller seeds, irrespective of fire. Changes in seed removal after fire seems to be mediated by changes in microhabitat cover. Plants whose seeds are often preyed upon by vertebrates likely benefit in the short-term from fire to escape predation, while the opposite would be true for those removed by granivorous ants (e.g., seeds < 1 g). Therefore, as long as seeds are available, fire in gallery forests may create pulses of opportunities for certain plant species to recruit, while constraining others.