Effects of land reclamation on peatland carbon stability in Sanjiang Plain (Northeast China) over the last century

Peatlands store vast amounts of soil carbon and the stability of this carbon pool plays a crucial role in the carbon dynamics under global change. In the Sanjiang Plain, one of the important peatlands distributed region in China, peatlands were seriously affected by the regional land reclamation during the last century. While, there is a scarcity of data evaluating the impact of land reclamation on peatland carbon stability. Here, based on ²¹⁰Pb dating of the Shenjiadian (SJD) peatland, we reconstructed historical variations in peatland carbon stability and assessed its response on regional land reclamation over the last century in the Sanjiang Plain. The results showed that the highest aromatic content (25.2 ± 0.7 %) and the lowest carbohydrate content (34.7 ± 2.5 %) occurred between 1950 and 1980, coinciding with the period of extensive second land reclamation in the Sanjiang Plain. The increase in regional human activities led to greater accumulation of pyrogenic carbon in the peatland, enhancing carbon stability in the 1950 s. However, as farmland area continued to grow in the 1960 s, local fires caused by agricultural activities led to more frequent peat fires, promoting the accumulation of herbaceous litter in the peatland, which decreased the stability of the peatland carbon pool but increased carbon accumulation rates. With the proportion of shrub litter increasing and regional land reclamation weakening after 1980, the accumulation of shrub litters has increased both carbon stability and carbon accumulation rates in the studied peatland, particularly after 2000.