Priming effect stimulates carbon release from thawed permafrost
AbstractClimate warming leads to widespread permafrost thaw with a fraction of the thawed permafrost carbon (C) being released as carbon dioxide (CO2), thus triggering a positive permafrost C-climate feedback. However, large uncertainty exists in the size of this model-projected feedback, partly owing to the limited understanding of permafrost CO2 release through the priming effect (i.e., the stimulation of soil organic matter decomposition by external C inputs) upon thaw. By combining permafrost sampling from 24 sites on the Tibetan Plateau and laboratory incubation, we detected an overall positive priming effect (an increase in soil C decomposition by up to 31%) upon permafrost thaw, which increased with permafrost C density (C storage per area). We then assessed the magnitude of thawed permafrost C under future climate scenarios by coupling increases in active layer thickness over half a century with spatial and vertical distributions of soil C density. The thawed C stocks in the top 3 m of soils from the present (2000–2015) to the future period (2061–2080) were estimated at 1.0 (95% confidence interval (CI): 0.8–1.2) and 1.3 (95% CI: 1.0–1.7) Pg (1 Pg = 1015 g) C under moderate and high Representative Concentration Pathway (RCP) scenarios 4.5 and 8.5, respectively. We further predicted permafrost priming effect potential (priming intensity under optimal conditions) based on the thawed C and the empirical relationship between the priming effect and permafrost C density. By the period 2061–2080, the regional priming potentials could be 8.8 (95% CI: 7.4–10.2) and 10.0 (95% CI: 8.3–11.6) Tg (1 Tg = 1012 g) C year−1 under the RCP 4.5 and RCP 8.5 scenarios, respectively. This large CO2 emission potential induced by the priming effect highlights the complex permafrost C dynamics upon thaw, potentially reinforcing permafrost C-climate feedback.
Авторы
He Mei1
,
Li Qinlu1,2
,
Chen Leiyi1
,
Qin Shuqi1
,
Kuzyakov Yakov3,4
,
Liu Yang1,5
,
Zhang Dianye1
,
Feng Xuehui1,2
,
Kou Dan1,6
,
Wu Tonghua7
,
Yang Yuanhe1,2
1 State Key Laboratory of Vegetation and Environmental Change Institute of Botany, Chinese Academy of Sciences Beijing China
2 University of Chinese Academy of Sciences Beijing China
3 Department of Soil Science of Temperate Ecosystems, Department of Agricultural Soil Science University of Göttingen Göttingen Germany
4 Peoples Friendship University of Russia (RUDN University) Moscow Russia
5 College of Resources and Environmental Sciences Hebei Agricultural University Baoding China
6 Department of Biological and Environmental Sciences University of Eastern Finland Kuopio Finland
7 Cryosphere Research Station on the Qinghai-Tibet Plateau, State Key Laboratory of Cryospheric Science Northwest Institute of Eco-Environment and Resource, Chinese Academy of Sciences Lanzhou Gansu China