VARIAÇÕES NOS ATRIBUTOS MICROBIOLÓGICOS DO SOLO NA FLORESTA AMAZÔNICA ORIENTAL, SOB CONDIÇÃO NATURAL, ESTRESSE HÍDRICO E EM SISTEMAS DE MANEJO.

This study aimed to evaluate the influence of water stress on long-term drought experiment in the forest (ESECAFLOR) and on the conversion of forest to agricultural area on soil microbiological attributes in the Caxiuanã National Forest. Four areas were selected, two of the drought experiment in the forest: control (Plot A) and exclusion of rainfall (Plot B); and two more: secondary forest (FS) and farm. Gravimetric humidity, carbon and nitrogen levels of microbial biomass (CBM and NBM), basal respiration (RB) were evaluated and the metabolic (qCO2) and microbial (qMIC) ratios were calculated. The areas presented, in general, had higher levels of CBM and NBM during the rainy season. The soil of the FS area presented higher values of moisture and higher values of CBM and NBM. The reduction of soil moisture in Plot B affected the microbial biomass mainly during the rainy season. The Plot B presented high values of RB and consequently qCO2. The microbiological indicators were sensitive to the changes in the edaphic environment provided by the long-term drought experiment in the forest and by the change in the form of land use. [ABSTRACT FROM AUTHOR]