Soil microbial biomass and activity under natural and regenerated forests and conventional sugarcane plantations in Brazil

The objective of this study was to evaluate the changes in soil microbial biomass and activity after the regeneration of deforested and cultivated soil in Brazil. Soil sampling was carried out in June and December 2007 (wet and dry seasons, respectively), at four areas, including: a native forest (NF), a 10 years old regenerated forest (RF10), a 20 years old regenerated forest (RF20) and a conventional sugarcane plantation (CL). Microbial biomass C, substrate-induced respiration and cellulase, saccharase, hydrolysis of fluorescein diacetate and dehydrogenase activities were analyzed. The microbial variables varied significantly among different areas depending on the season. Usually, larger differences were observed in the RF10 than in others, in dry season, for soil microbial biomass C and enzyme activities. The multidimensional scaling analysis showed that the RF10 has distinct microbial and biochemical characteristics comparing with the other areas. In general form, microbial activity, as measured by enzyme activities, is higher in native forest and regenerated lands than in cropland.

► Regeneration of forest may return C storage to pre-agricultural levels.
► Microbial biomass has been shown to be an early indicator of soil changes.
► Regenerated forest shows a trend of long-term regeneration in the microbial biomass.