Drainage-Driven Loss of Carbon Sequestration of a Temperate Peatland in Northeast China

Abstract

Drainage is known to reduce carbon sequestration in peatlands, but its effect on the stability of carbon pool and changes in recalcitrant organic carbon fractions remain relatively unknown, especially in temperate montane peatlands. We investigated the effect of drainage on physicochemical properties and organic carbon fractions of six peat cores from drained and near-pristine areas of Baijianghe peatland, NE China, basing on ²¹⁰Pb and AMS ¹⁴C dating. The vegetation biomass and biomass-C sequestration were also measured in both areas. The loss of total soil carbon accumulation due to drainage was 7.5 kg m⁻² (− 25%), equivalent to a complete consumption of carbon accumulated for nearly 170 years in the near-pristine area. Vegetation succession after drainage had a little positive effect on ecosystem carbon sequestration, with an increase of 0.26 kg m⁻², which compensated for only 3.5% of the peat soil carbon loss. Notably, over 80% of the total carbon loss after drainage was attributed to the loss of the recalcitrant carbon fraction. The study emphasizes the crucial impact of drainage on carbon sequestration in temperate peatlands. Our findings suggest that continuous water table drawdown induced by drainage, together with drought driven by climate warming, will further reduce carbon sequestration in drained peatlands. There is an urgent need to restore hydrology of peatlands in order to mitigate the long-lasting negative effect of drainage.