Altered soil carbon dynamics under different land-use regimes in subtropical seasonally-dry forests of central Argentina

Abstract

Background and aims Subtropical seasonally dry forestsfrom South America are now experiencing one ofthe highest rates of forest-cover change globally. Thesechanges may affect the dynamics of soil organic carbon(SOC) including long-term stabilization processes, withprofound consequences for the fertility and carbon storageof these ecosystems.Methods In order to explore the effect of different landuseregimes on SOC dynamics, we determined theamount and quality of plant litter, the amount and quality(lignin and carbohydrate content) of SOC, and thesoil basal respiration rates across seasonally dry Chacoforests of Argentina.Results Changes in land-use regimes significantly reducedthe amount of litter but not its quality. As aconsequence, the SOC content was also reduced togetherwith SOC quality. Unexpectedly, we found a higherCO2 release per SOC unit in soils with lower amountand quality of SOC.Conclusions The results presented here show a cleareffect of different land-use regimes on SOC dynamicsthrough a reduction in the amount and quality of SOC.Additionally, we found that potential microbial activityis somehow disconnected from substrate quantity andquality, suggesting that the molecular structure of SOCis not significantly affecting long-term soil stabilizationprocesses across these seasonally-dry ecosystems.