Variações na estrutura da vegetação pós-fogo em parcelas com exclusão de fauna, Pantanal sub-região do Abobral/Miranda, Corumbá-MS.

Abstract

Fire and flooding are frequent events in the Pantanal and directly affect the local fauna and flora. Therefore, understanding how vegetation is structured in areas with and without the presence of large mammalian fauna becomes a valuable tool that contributes to understanding the process after the passage of these environmental filters. This work aimed to verify variations in the richness and composition of plant species in experimental plots excluding fauna and the impact that these animals cause on vegetation after prescribed fire and flooding activity. To assess the impact of fauna on plant species, an animal exclusion plot method was used, which consisted of establishing four 5m x 5m enclosures, one in each of the four plots with burning treatments (with the presence or absence grazing), with control treatments established in four other plots (without exclusion and without burning). Within the established treatments, phytosociological data was collected. For statistical analysis, we considered species richness and composition data using GLM, ordination and classification analyses. The results showed that the exclusion of fauna was not preponderant in the variation in species richness as expected (p<0.1) and that the factor that had the most influence was the presence or absence of fire, with a tendency towards greater species richness in the treatments after the passage of the fire (p<0.01) regardless of the exclusion of fauna, possibly due to the resilience of rural vegetation to the effect of fire and its effect of stimulating the regrowth of some species. However, the flood caused a tendency towards a decrease in post-fire richness in the treatments. We can conclude that species that regenerate well post-fire end up competitively excluding species that could benefit from flooding, especially if herbivory is absent, in addition to changes in flood patterns in recent years possibly affecting vegetation responses. In the ordination and classification analyses, it was not possible to observe the effect of treatments on the composition of plant species. Therefore, based on the results of this study, fire proved to be the more important factor in variation in plant species richness than flooding and herbivory by large mammalian fauna.