Impacto do fogo sobre a microbiota edáfica em diferentes fitofisionomias do Pantanal em Mato Grosso

Abstract

Microbial diversity has been studied in Pantanal Matogrossense and the effect of this interactive with the environment has been studied, what makes these microorganisms as an excellent bioindicator to assess the sustainability of the ecosystem. Due to limited knowledge about the factor fire influence on microbial population in vegetation of pantanal, the objective of this work was study and evaluate quantitatively the dynamics of bacteria and fungi in soil in five existing impacted phytophysiognomies or not by the action of fire on SESC Pantanal, Mato Grosso. The collections of samples were performed in five different phytophysiognomies in RPPN SESC Pantanal, MT. The whole area was divided into two tranches (occurrence of fire or not), and such fire occurred between August 30 and September 11, 2005. In September 2005, were collected for each parcel of 20m2, five samples of soil in the depth of 0 – 10 cm. For microbiological analysis, triplicates was used for technical tube followed by multiple counting of fungal and bacterial colonies, with dilutions 10-3 and 10-5, respectively, with readings of 24, 48 and 72 h. For arbuscular mycorrhizal fungi (AMF), the spores were extracted from soil by the sifting method of through wet combined with the centrifuge technique as sucrose, is quantifying the number of spores in 50mL of soil per sample. The number of colony-forming units (CFU) bacterial and fungal infections was higher in the plots with fire (162.52 CFU bacterial and fungal 24.95 CFU / g of soil, respectively, and 106.64 CFU bacterial and fungal 10.88 CFU respectively in areas without burning). Conversely for the FMA, got up 9.44 spores/50mL of soil under natural conditions against 5.04 of the areas burned. The impact of fire was significant for the bacterial population in espinheira baixa phytophysiognomy (ESB) and the population of FMA in the open “cerrado” vegetation or grasses (CAP). The action of fire did not interfere significantly on the total population in fungal phytophysiognomies studied. The action of fire is more intense on the cambarazal vegetation (CAM) and ESB, both considered as secondary 11 vegetation. Although fire has caused little variation on the physical and chemical factors of vegetation CAP, cerrado (CEC) and decidual forest with bamboo (MDB), it was concluded that indirect action of burning contributed positively to the microbial population in the plots burned.