Abstract
To understand the past carbon accumulation of forest–steppe ecotone and to identify the main drivers of the long-term carbon dynamics, we selected Huangqihai Lake and analyzed the sediment records. We measured the organic carbon content (TOC; %) of sedimentary samples and quantified the carbon accumulation rate (CAR; g C m−2 yr−1). Furthermore, the climate, soil erosion, and vegetation development of the past 6800 years were reconstructed using physicochemical parameters and pollen records. Human activities were also obtained from a 2200-year history record. Our results showed that the CAR was high during 5800~4100 cal yr BP (40~60 g C m−2 yr−1), which is mainly attributed to the high sediment accumulation rate (SAR) during this period. Pearson’s correlation, redundancy analysis and hierarchical variation partitioning analyses suggested that the CAR was influenced by the SAR and TOC, while vegetation dynamics (broadleaved tree percentage and vegetation coverage) and local soil erosion were the main drivers of the TOC and SAR. Especially when the vegetation was dominated by broadleaved forests, the CAR was significantly high due to the high gross primary productivity and carbon density of forest compared with steppe. Our study highlights the direct influence of local vegetation and soil erosion on the CAR, whereas climate might influence indirectly by changing local vegetation and soil conditions. Moreover, our results showed that human activities had positive influences on the carbon accumulation dynamics in this region since 2200 cal yr BP by influencing the SAR.
Highlights
Global climate change caused by the rapid emission of carbon dioxide (CO2 ) and other greenhouse gases since the Industrial Revolution has attracted increasing public attention [1]
This study focuses on carbon dynamics in the sediments of the Huangqihai Lake in forest–steppe ecotone of northern China and investigates their possible influencing factors, especially the vegetation change during the Holocene
Since sediment accumulation rate (SAR) varied more significantly than total organic carbon (TOC), the−1 temporal variation about 5800 cal yr BP, and thereafter increased greatly
Summary
Global climate change caused by the rapid emission of carbon dioxide (CO2 ) and other greenhouse gases since the Industrial Revolution has attracted increasing public attention [1]. Many studies investigated carbon burial in different Holocene lakes in China [14,15,16,17], few of them attempted to provide detailed information on carbon deposition as well as its potential environmental and anthropogenic factors, such as the climate, vegetation dynamics and human activities [9,11]. This study focuses on carbon dynamics in the sediments of the Huangqihai Lake in forest–steppe ecotone of northern China and investigates their possible influencing factors, especially the vegetation change during the Holocene. This information will help us better predict how carbon dynamics in lake sediments will respond to future climate change, vegetation succession and human activities
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