Ocorrência de microrganismos em Latossolo da Floresta Nacional de Caxiuanã, Melgaço (Pará)

Abstract

The study of soil microbiology is of great importance for a better understanding and knowledge of the functions performed by microbial communities in terrestrial environments. Microorganisms, by emitting COz to the atmosphere through respiration and decomposition of organic matter, contribute to the greenhouse effect and also control the flow of energy and nutrients in the ecosystem, promoting nutrient recycling. The present work evaluated the microbiological growth in the soil of the preserved area of the Caxiuanã National Forest. The study sites were demarcated in the ESECAFLOR-Drought Experiment in the Forest (A and B) and in the LBA Micrometeorological Observation Tower (T). The study of the occurrence of microorganisms in the sites aims to verify the effect of water exclusion on soil and vegetation characteristics. The soil, classified as Latosol, was sandy and well drained at sites A and B, and clayey and moderately drained at site T. Simple soil samples were taken at five collection points around each profile. Soil was collected in the superficial layer (0-10cm depth) of the rainy season (January 2001). The methods used for microbiological evaluation were serial dilution and pour plate plating techniques. Microbial quantification was determined by fungal and bacterial colony counts. Preliminary results showed that there are differences in microbiological growth between the sites studied. The highest and lowest occurrence of microorganisms was observed in sites B and A, respectively. In these sites, the highest occurrence was fungi, while in site T, bacteria were predominant. According to the results obtained it is concluded that for the local conditions, in sandy and well drained soils the conditions are favorable to fungal predominance that intensifies a greater microbiological growth.