The development of Hani peatland in the Changbai mountains (NE China) and its response to the variations of the East Asian summer monsoon.

The past ecosystem responses to climate variability makes it possible to view the sensitivity of ecosystems to climate-forced state shifts. To test the hypothesis that the development of peatland in the Changbai Mountains responds to the variability of the East Asian summer monsoon (EASM), the developmental history of the Hani peatland was investigated based on peat basal ages. It can be concluded that the development of Hani peatland is the paludification. The development of the northern region started 13,685 cal. yr BP, while that of the southern region was initiated 7705 cal. yr BP. In addition, the moisture changes and development of the Hani peatland can be divided into three periods. From 16 to 7 ka cal. BP, the increase in the EASM was induced by the lower sea level and southward displacement of the Western Pacific Subtropical High (WPSH), resulting in increasing moisture in the Hani peatland. Peat was gradually established in the northern region. From 7 to 2 ka cal. BP, the increased relative sea level and northward displacement of the WPSH induced the maximum EASM. The EASM and Northeast Monsoon (NEM) induced the maximum moisture in the Hani peatland. Both the northern and southern regions were covered with peat during this period. Since 2 ka cal. BP, the decreasing EASM might be related to the seasonal decrease in the Northern Hemisphere summer insolation and ENSO intensity. Thus, the decreasing EASM induced the decrease in the moisture in the Hani peatland. Peat further accumulated in both the northern and southern regions. This study will help to understand the future EASM behavior in NE China and the development of similar peatlands in response to ongoing and future climatic change.