Do selective logging and pine plantations in humid subtropical forests affect aboveground primary productivity as well as carbon and nutrients transfer to soil?

Abstract

Land use changes due to forestry activities can alter forest carbon (C) sequestration capacity by modifying vegetation structure and ecosystem functioning. The main objective of this study was to analyze aboveground net primary productivity (aNPP), through stem growth and litterfall production, and their feedback on soil C and nutrient contents, within a humid subtropical region. Two main forestry activities in NE Argentina were studied: selectively logged forests and Pinus taeda (loblolly pine) plantations for wood production. Well-preserved native forests were used as a control to compare the effects of interventions on the original subtropical forests. Despite differences in tree density and aboveground biomass among forests and pine plantation stands, the aNPP and total annual litterfall were similar across all ecosystems. However, litterfall quality and soil N content were substantially lower in pine plantations compared to both native forests. The labile soil C fractions were higher in pine plantations than native forests while no differences were observed in recalcitrant humic fractions across ecosystems. Overall, the results of this study suggest that man-made intervention in the structure of forest ecosystems does not necessarily result in degradation of aboveground ecosystem processes but had an impact on belowground processes and stocks in pine plantations, which has important implications for forest management.