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This paper documents a 7800-year proxy record from the Shenjiadian peatland on the Sanjiang Plain in Northeast China. High-resolution plant macrofossil and colorimetric humification methods were used to reconstruct the vegetation and hydrologic history from a 193 cm-long sedimentary profile. Detrended correspondence analysis (DCA) was applied to transform the raw plant macrofossil data into latent indices of peatland water level. The vegetation community transited from an Equisetum fluviatile community to a Carex lasiocarpa community at approximately 3800 cal yr BP and was followed by a Carex-shrub community at approximately 480 cal yr BP. Based on the plant macrofossil DCA axis 1 scores and humification values, we distinguished four hydrologic periods: a wet period from 7800 cal yr BP to 4500 cal yr BP, dry periods up to 1600 cal yr BP, drier periods until 300 cal yr BP, and the driest period from 300 cal yr BP until the present. Through a comparison with other climate records, we suggest that the East Asian summer monsoon (EAM) was the main driving force for vegetation and water level changes to the Shenjiadian peatland through its impacts on precipitation. [ABSTRACT FROM AUTHOR]

The evolution of Holocene climate was investigated using grain size and magnetic susceptibility of the Holocene paleosols from Baicaoyuan (BCY), Xifeng (XF) and Linyou (LY) sections in the northwest, central and southern Chinese Loess Plateau (CLP). The results show that the Holocene in the BCY, XF and LY paleosol sections could be divided into three phases: during the early Holocene (11.8–10.5 kyr B. P.), increased magnetic susceptibility (χ) and frequency-dependent magnetic susceptibility (χfd) and decreased median grain size (Md) indicate that the East Asian Summer Monsoon (EASM) has become more intense and the climate has changed from cold to warm. During the middle Holocene (10.5–5.0 kyr B. P.), the values of χ, χfd and 2–5 µm grain-size fraction (GT2/5) are higher and Md and 30–63 µm grain-size fraction (GT30/63) are the lowest, which reflect a warm and humid regional climate. At ∼ 8.0 kyr B. P., there was a transient dry-cold climatic spike corresponding to a Heinrich Event, the cold event was likely due to the collapse of the Laurentide ice sheet. During the late Holocene (5.0–0 kyr B. P.), χ and χfd values are the lowest, while Md and GT30/63 are high, as proxies of a weakened EASM, when the dry-cold climate prevailed in the region. Decreased irradiance since 5.0 kyr B.P. may have caused climatic cooling and drying. Spatially, the increased main peak values and skewness from BCY, XF to LY sections show that the grain size became fine, the East Asian Winter Monsoon (EAWM) reduced, and climate was warmer and wetter from northwest to southeast. In addition, Md can be used as alternative proxy for EAWM, while χfd is positive with the intensity of EASM under semiarid climate conditions in CLP. [ABSTRACT FROM AUTHOR]