Differences in plant-dispersal mechanisms between contrasting Brazilian savanna habitats

Abstract

ABSTRACT Background By favouring long-distance dispersal, anemochory is often associated with open and patchy habitats, whereas zoochory enables short-distance dispersal and prevails in closed and extensive habitats. Brazilian savanna (Cerrado) on shallow rocky soils (RS) have open vegetation and are patchily distributed, whereas savanna on deep soils (DS) have dense vegetation and occur in large stands. Thus, we predicted that zoochory would be favoured in DS and anemochory would characterise RS. Aims We tested the hypothesis that vegetation structure and distribution patchiness are related to the characteristic dispersal mechanisms associated with closed and open habitats. Methods We compared the abundance of dispersal mechanisms between DS and RS with generalised linear mixed models and used an indicator species analysis to identify species associated with each vegetation type. Results There was no difference between DS and RS in the number of species associated with one or the other dispersal mechanism. We found fewer-than-expected zoochorous individuals and more-than-expected anemochorous individuals in RS, and more zoochorous indicator species in DS. Conclusion Habitat patchiness and openness are related to the composition of dispersal mechanisms. Open vegetation on shallow rocky soils favours long-distance dispersal relative to zoochory. This implies reduced plant establishment and increased leaflessness, being harsher on animal dispersers. Protected areas are often concentrated in RS, whereas DS are rapidly converted into croplands due to their excellent aptitude for mechanised agriculture. Conserving DS and RS requires a balanced complementary approach, that ensures that all landscape elements are adequately represented in protected areas.