Simultaneous Measurements of Dissolved Organic Carbon and Soil Respiration Reveal Reduced Soil Carbon Loss Under Nitrogen Addition in a Montane Forest

Abstract

Forest ecosystems represent one of the largest carbon (C) reservoirs in terrestrial environments globally (Keenan & Williams, 2018;Scharlemann et al., 2014). Almost half of the C is stored in soils up to 1 m depth (Pan et al., 2011). Recent estimates have shown that forest soils are a C sink and play a critical role in the mitigation of future anthropogenic CO 2 emission (Pan et al., 2011;Tagesson et al., 2020). However, these estimates are often associated with large uncertainties. A major uncertainty in estimates of forest soil C sink lies in the effects of anthropogenic N input on the balance between plant C input and soil C loss. Nitrogen addition from enhanced N deposition generally increases plant growth and thus C input into soils (LeBauer & Treseder, 2008). However, the soil C loss response to N addition is not well understood, largely because recent research has mainly been concerned with only one pathway of soil C loss.