Short-term effects of forest management on soil microbial biomass and activity in caatinga dry forest, Brazil

Abstract

The Caatinga is among the most threatened and least studied tropical dry forests in the world. Sustainable forest management is a rational exploitation practice adopted in the biome, but it can impact a variety of ecosystem attributes. We still have a limited understanding of forest management impacts on the soil, especially on microbial biomass. Thus, we developed this work by asking how do soil microbial biomass and activity respond in the short-term to Caatinga forest management and how do these responses differ between forest management practices? Three types of forest management were evaluated (clear cutting - CC, selective cutting by diameter - SCD, and selective cutting by species - SCS), using unmanaged Caatinga (UC) as a reference. Litter and soil (depth of 0–10 cm) collections were carried out. Soil microbial activity was determined based on the amount of evolved CO2, and the microbial biomass C and N were estimated by the fumigation-extraction method. The management provided a reduction in leaf litter (CC = 16%; SCD = 25%; SCS = 38%; UC = 55%) and an increase in branch litter (CC = 73%; SCD = 66%; SCS = 46%; UC = 35%). It also caused a 42% reduction in MB-C. The metabolic quotient had an increase in CC and SCD management (average of 690.6 mg g−1 day) compared to UC (365.9 mg g−1 day). SCD and CC influenced the activity and C transformation of soil microbial biomass in the short-term, while SCS less intensely affected these variables, approaching the unmanaged forest condition.