Late Holocene Natural and Human-Induced Environmental Change Reconstructed from Peat Records in Eastern Central China

Abstract

ABSTRACT. We present a high-resolution multiproxy record (geochemistry, macrofossil, and pollen) from a peatland in the Dajiuhu Basin in eastern central China. The chronology of the 120-cm peat profile was controlled by 6 accelerator mass spectrometry (AMS) 14 C dates on plant remains, including 2 post-bomb dates. The age model was based on linear interpolations of calibrated ages. Plant macrofossil results indicate a major transition around 3600 cal BP from Sphagnum section Subsecunda and Drepanocladus sp. to Sphagnum imbricatum dominance, followed by the disappearance of S. imbricatum at 700 cal BP. These changes suggest a general sequence of local environment changes from a wet fen, through a Sphagnum-dominated peatland, to a dry sedge-dominated marsh, which are also reflected by change in peat lithology and composition. The drying trend after 3600 cal BP is in general agreement with the speleothem isotope record from this region and other paleoclimate records from east China, indicating a weakening summer monsoon resulting from a decrease in summer insolation. The shift to a dry environment at 700 cal BP might have been caused by human activities. Appearance of Cerealia pollen at 3600-3200 cal BP suggests the first introduction of crop farming in the region, while its absence at 3200-2000 cal BP could be attributed to abandonment of farmland. The increase of Ti and Si since 1300 cal BP may be related to agricultural activity and landscape erosion. A 2-step increase in Pb concentration at 1600 and 600 cal BP suggests 2 phases of industrial pollution intensity.

Record of environmental change by α-cellulose δ 13C of sphagnum peat at Shennongjia, 4000–1000 aBP

“…This trend is also observed in large fossil plants and pollen records [17] . Stalagmite oxygen isotope at Sanbao cave in Shennongjia reveals a similar history [34] .…”

“…Because of its unique geographic situation, a lot of researches have been conducted in the Dajiuhu Basin. For example, Li and Liu et al [14,15] carried out pollen analysis for paleo-vegetation reconstruction, He et al [16] used magnetic parameters as climatic proxy; Zhao et al [17] suggested geochemical elements variation could be the indicators of human disturbance of the basin; Ma et al [18] reconstructed the history of monsoon variation since Late Glacial. Here we attempt to delineate the paleoclimatic significance of -cellulose  13 C in sphagnum peat, and then discuss the environmental change and monsoon variation of Shengnongjia during Late Holocene.…”

Climate changes in East China since the Late-glacial inferred from high-resolution mountain peat humification records

“…Yet broadleaf trees like birch and deciduous oaks took on high percentage and belonged to deciduous broad-leaved forest, which reflected dry climate condition. Moreover, Zhao et al's study of pollen, plant macrofossils and geochemistry elements to another peat profile of 120 cm (continuous sediments since about 4.7 cal ka BP) in Dajiuhu shows the similar climate feature [36] . Namely, the climate became dry after about 3.6 cal ka BP.…”

Using Ecological Niche Modelling to Predict Spatial and Temporal Distribution Patterns in Chinese Gibbons: Lessons from the Present and the Past

“…Faunal and environmental data both suggest that the subtropical Oriental Realm and its associated mammal fauna extended as far north as the Qinling Mountains throughout the glacial-interglacial cycles of the Late Quaternary [Yang, 1986], and although some (often regional or local) relatively small-scale climatic fluctuations are known from the late Holocene of China, these are much less significant than either the large-scale shift from glacial to interglacial conditions at the Pleistocene-Holocene boundary or even other fluctuations that occurred during the early-middle Holocene [Tao et al, 2006;Zhao et al, 2007]. Indeed, records from the last two millennia almost cer tainly represent climatic conditions that are closely similar to those found today [Roberts, 1998].…”