Holocene peatland initiation, lateral expansion, and carbon dynamics in the Zoige Basin of the eastern Tibetan Plateau

Abstract

The Zoige Basin on the eastern Tibetan Plateau has the largest area of highland peatlands in China. However, the development history of these peatlands is still poorly understood. Understanding how these carbon-rich ecosystems responded to change in the Asian summer monsoons during the Holocene will provide insight into the peatland carbon accumulation processes under different climate boundary conditions. Here, we document the timing of initiation and expansion histories of these peatlands using 59 new basal peat ages across the Zoige Basin, with 29 ages for initiation analysis and 30 additional ages for lateral expansion analysis. Also, we synthesized basal ages from 26 sites and carbon accumulation records at four sites from previous studies in this region. The results show that the peatland initiation is widespread at 11.5-10 and 7-6 kyr (1 kyr = 1000 cal. yr BP) and the minimum initiation periods occurred after 5 kyr. Our multiple basal ages along eight transects show that slopes are a dominant control on peatland lateral expansion rates, with very slow and less variable rates at slopes >0.4°. Furthermore, we found a significant relationship between peatland basal ages and peat depths from 85 sites, suggesting relatively uniform peat properties. Carbon accumulation rates from detailed downcore analysis at four sites and on the basis of peat depth-basal age relationship show similar patterns with a peak carbon accumulation at 10-8 kyr. On the basis of estimated mean values of bulk density and carbon content from the region, the Holocene average C accumulation for the Zoige Basin is 31.1 g C/m 2 /yr. The widespread peatland initiation and rapid accumulation in the early Holocene were likely in response to higher temperature and stronger summer monsoon intensity, while the slowdown of peatland development during the late Holocene might have been caused by climate cooling and drying.

Drivers of Holocene peatland carbon accumulation across a climate gradient in northeastern North America

“…Changes in Holocene peatland carbon accumulation also support the contention that temperature drives carbon accumulation rates at millennial timescales over northern peatlands as a whole (Yu et al, 2009Loisel et al, 2014;Yu et al, 2014a) and at regional scales (e.g. Jones and Yu, 2010;Garneau et al, 2014;Zhao et al, 2014). On submillennial timescales, the Medieval Climate Anomaly and Little Ice Age also appear to have affected peatland carbon accumulation rates (e.g.…”

Lake–mire ecosystem transformation and its possible forcing mechanisms in volcanic landform regions: a case study in the Gushantun peatland of northeast China

“…Regional climate (precipitation and evaporation effects) is another important factor for peatland development (Filion and Begin, 1998;Yu et al, 2010;Ireland et al, 2013;Zhang et al, 2019aZhang et al, , 2019bZhang et al, , 2020. It is a common view that wetter moisture is good for the accumulation and expansion of peatlands (Jones and Yu, 2010;Zhao et al, 2014aZhao et al, , 2014bKalnina et al, 2015). Effective moisture refers to the results of precipitation minus evaporation (Chen et al, 2016).…”

Paleoenvironment change and its impact on carbon and nitrogen accumulation in the Zoige wetland, northeastern Qinghai‐Tibetan Plateau over the past 14,000 years

“…Peat is a special type of soil that is very rich in organic matter (OM), formed by the deposition and decomposition of clastic particles and OM that have undergone microbiological and physicochemical transformations over a long term [ Chai , ; Charman , ]. Peat is widely distributed around the high‐elevation Zoige wetland in the northeast margin of the Qinghai‐Tibet Plateau (QTP), with a mean depth of 3 m and depths exceeding 10 m in some landforms [ Li et al ., ; Zhao et al ., ]. The OM in peat is controlled by the source and transformation of the parent material during the decomposition process, and the indicators origin from OM can reserve some signatures of environmental factors, such as moisture and biology [ Charman , ].…”

“…Located in the transition zone where from the QTP to the lowland and within the peripheral area of the Asian summer monsoon (ASM), the Zoige wetland, which is the largest alpine wetland, is extremely sensitive to climate change and is considered a global carbon (C) sink [ Bragazza et al ., ]. Many interpretations of C dynamics have been completed on the Zoige peat [ Gao et al ., ; Ma et al ., ; Wang et al ., ; Zhao et al ., ], but the research from a long‐term perspective is deficient and controversial [ Wang et al ., ; Zhao et al ., ]. Nitrogen (N) is an important macronutrient element that accompanies C and is thus strongly couples to C accumulation [ Hessen et al ., ].…”

“…Located in the transition zone where from the QTP to the lowland and within the peripheral area of the Asian summer monsoon (ASM), the Zoige wetland, which is the largest alpine wetland, is extremely sensitive to climate change and is considered a global carbon (C) sink [Bragazza et al, 2012]. Many interpretations of C dynamics have been completed on the Zoige peat Ma et al, 2016;Wang et al, 2015;Zhao et al, 2014], but the research from a long-term perspective is deficient and controversial [Wang glacial landscape surrounded by mountains in which the elevation ranges from 3000 to 4000 m, with an average value of 3400 m. Gentle hills, broad valleys, and terraces are developed widely in this region. Peatbog, sedge marsh, lake, grassland, and alpine meadows flourish in different geomorphic landscapes.…”