Microbiological attributes of the soil under eucalyptus areas and seasonal forests

Abstract

Forests are capable of sequestering and storing large amounts of carbon (C) in biomass and, over time, this carbon is cycled and incorporated into the soil. Cultivation of forest species, such as of eucalypts are beneficial for incorporating C, however, these are poor in diverse systems when compared to native Cerrado forests. Based on the premise that microbiological activity should be higher in native areas due to less human interference, the objective of this study was to verify the effect of eucalyptus forests on soil quality bioindicators when compared to semi-deciduous seasonal forests. The study was conducted in two different forest systems: semideciduous seasonal forest (FES) of the Cerrado and forest of Eucalyptus spp. located in the southeastern region of Goiás. For each forest system, three fragments were analyzed, totaling six fragments. In each fragment, three transects were demarcated and subdivided into ten 10 m x 10 m subplots. A randomized block design with subdivided plots was used, where each plot was considered a block. In each subplot, soil samples were collected and used to determine microbial biomass carbon (MBOC), microbial respiration (MR), metabolic quotient (qCO2), microbial quotient (qMIC), total organic carbon (TOC) and organic matter (OM). The results show that only qCO2 did not differ statistically between FES and eucalypts, with the other variables showing higher values of microbial activity and incorporation of C when compared to eucalyptus. This is also confirmed by the analysis of variance and PCA, where the FES fragments were statistically different and superior to the three eucalypt forest fragments. When looking at FES fragments, especially regarding the sequestration of C, these present more microbiological activity and greater storage of C. The values of BOD of the native area showed an average of 568.84 mg C.kg-1 of soil, more than double than the incorporation of the planted area; where the incorporation was 227.30 mg C.kg-1 of soil, which alos the case in TOC and MO. The results of the research contribute to the initial construction of a concrete database for the environmental regularization of the preservation of forest areas, when we associate the FES with microbiological activity of C storage.