Mineral protection controls soil organic carbon stability in permafrost wetlands

Mineral protection can slow the effect of warming on the mineralization of organic carbon (OC) in permafrost wet-lands, which has an important impact on the dynamics of soil OC. However, the response mechanisms of wetland min-eral soil to warming in permafrost areas are unclear. In this study, the soil of the southern edge of the Eurasian permafrost area was selected, and bulk and heavy fraction (HF) soil was subjected to indoor warming incubation ex-periments using physical fractionation. The results showed that the HF accounted for 51.25 % of the total OC miner-alization in the bulk soil, and the delta 13C value of the CO2 that was emitted in the HF soil was higher than that of the bulk soil. This indicates the potential availability of mineral soil and that the mineralized OC in the HF was the more stable component. Additionally, the mineralization of the mineral subsoil after warming by 10 degrees C was only about half of the increase in the organic topsoil, and the temperature sensitivity was significantly negatively correlated with the Fe/Al oxides to OC ratio. The results indicate that under conditions of permafrost degradation, the physical protection of mineral soil at high latitudes is essential for the stability of OC, which may slow the trend of permafrost wetlands be-coming carbon sources.