Estimation of China's peatland carbon stocks:Approaches,progress,and prospects
Peatlands,despite covering only 3％to 4％of the global land area,constitute a significant one-third of the global soil carbon pool and are closely linked to climate change.Understanding the variations in the carbon pool in peatlands,determined by the balance between net primary production(NPP)and organic decomposition,is crucial for comprehending the relationship between the global carbon cycle and global change.However,the response of the peatland carbon pool to climate change remains poorly understood,contributing to a significant source of uncertainty in climate projections.Consequently,the study of peatland soil carbon pools has attracted extensive attention as a research hotspot among scholars.This paper provides a concise summary and evaluation of three estimation methods for peatland carbon pools:The'peat volume approach',the'carbon density approach',and the'time history approach'.Each method is analyzed in terms of its advantages,disadvantages,and sources of uncertainty.The'peat volume approach'and the'carbon density approach'subjectively homogenize the thickness and carbon density of peat layers during the calculation process,neglecting the autogenic processes of peatlands,which can lead to potential errors.In contrast,the'time history approach',based on precise chronologies,calculates the net carbon balance of peatlands over time intervals and aggregates them to determine the size of the peatland carbon pool.Through the comparison of different studies on the distribution and area of peatlands in China,it is concluded that the most accurate estimate of China's peatland area is between 10.07×104 km2 and 13.70×104 km2.Additionally,several studies on peatland carbon pool estimation in northeastern China and the Zoige Basin indicate average values of 1.56 Gt C(0.14-4.34 Gt C)and 0.75 Gt C(0.39-1.42 Gt C),respectively.Furthermore,an analysis of peatland development and carbon accumulation characteristics in northeastern China,the Tibetan Plateau,and the Chinese subtropical monsoon region since the Holocene suggests that the primary driving factor for peatland development in northeastern China is the decline of the East Asian summer monsoon.Additionally,the carbon accumulation rate of peatlands is jointly determined by both summer solar radiation and monsoons.While the climatic and environmental mechanisms of peatland development on the Tibetan Plateau remain contentious,temperature is considered the primary factor promoting variation in the carbon accumulation rate in this region.In the Chinese subtropical monsoon region,a considerable number of peatlands developed during the MIS 3 period of the last glacial maximum and the B/A interglacial period.However,the majority of these peatlands have disappeared or been buried,with only a few remaining in mountain regions.Furthermore,since the Holocene,the development and variation characteristics of peatlands in the Chinese subtropical monsoon region have not been clearly evident due to high decomposition environments and strong human activities,necessitating further research.In terms of future predictions for China's peatland carbon pools,it is projected that the peatland carbon pools in northeastern China may increase over the next century.However,evaluating future changes in carbon pools in the Zoige Basin is challenging due to limited predictive research.Therefore,future studies should focus on updating the distribution and area of peatlands,improving peat carbon accumulation models,and enhancing the monitoring of peatland carbon fluxes.These efforts will contribute to establishing a relationship model between China's peatland carbon pools and climate-environmental factors.
peatlandsoil carbon poolChinacarbon peaking and carbon neutrality
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