Fine-scale effects of fire on non-woody species in a southern Amazonian seasonal wetland

Abstract

Grasslands and wetlands are non-forested highly biodiverse ecosystems. Although fire is a major factor controlling and maintaining biodiversity in different landscapes of Central Brazil, there are still knowledge gaps about its effect on these systems. We compared composition, diversity and coverage of herbaceous and sub-shrub species in ‘campos de murundus’ (murundus fields) before and after recurrent fire events. We sampled and collected species in 32 subplots of 1 m2 within a 100 × 100 m plot, and compared species richness, diversity, frequency, and cover percentage before and after recurrent fires. Floristic composition was evaluated through multivariate dispersion analysis. Our results show that recurrent fires in murundus fields decreased species richness and modified the composition of herbaceous and sub-shrub (i.e., species with a woody base and soft shoots) species. However, species diversity either increased or was maintained, depending on the diversity index used. In addition, repeated fire events modified the coverage and increased the dominance of fire-tolerant species, such as Aristida pendula, over fire-sensitive ones, such as Eriocaulon burchellii, Eleocharis minima, Hyptis hygrobia, Scleria sp., Paspalum lineare, Piriqueta sp., Polygala celosioides and Sipanea biflora. These post-fire changes resulted in altered species composition, richness and soil cover. Generally, fire increased the amount of bare ground and, consequently, decreased species richness and species diversity.