| Peatlands are very important archive in global climate changes research, and peat-based paleoclimate reconstruction is an important part of global change science. Peat-based climate reconstruction research since the Ming and Qing Dynasties is of great significance in understanding the future climate change trends and exploring the harmonious development between man and nature.Changbaishan mountains locates in sensitive area of global change with less human disturbance, constantly peat deposition, and well preserved since the Ming and Qing Dynasties, so they are the ideal regions for local climate change and human activity study. In this paper, we studied the peat profile which taken from Tinchuan mire and Jixiang mire in changbai mountain. Taking element geochemistry, phytoliths, granularity and Loss on Ignition as indexes, referncing historical literature record, we explored the relationship between climate change process and LUCC in changbai mountain area since the Ming and qing dynasties by using the AMS14 C and 210 Pb dating techniques, to provide basic information for the research of man-earth relationship.By using the AMS14 C and 210 Pb dating techniques, we establish the five hundred years time scale framework of the peat profile taken from Tinchuan mire and Jixiang mire. The results showed that peat profile 100 cm near-surface is deposited within 1000 AD. And the peat profile is constant, which is of great importance to the ancient climate research since the Ming and Qing dynasty.Principal component analysis and correlation analysis of geochemical elements in the peat profile show that Fe, Mn, Cr, Ni and Co are enriched in the warm and humid climate. Mn /Cr, Mg /Ca, Sr/Ba ratio can reflect the sedimentary environment of peat swamp sediments. The high ratios of Sr /Ba, Mg /Ca and Cr / Mn show that the climate is dry and cold. The low ratio showed that the climate is warm and humid. The trend of trace elements with time is consistent with the land development speed, indicating the pollution and destruction of human land development activities on the environment, corresponding to the rapid growth of land development in Changbai Mountain area.Tinchuan profile granularity frequency curves are given priority to with unimodal, which shows that sedimentary hydrodynamic condition is unitary. From down to up, composition of clay and silt decreases gradually. And the sand composition increases gradually, especially high within 30 cm. This is related to local vegetation degradation, surface runoff and human activity intensity gradually, which corresponds well with Jixiang profile. Silt clay ratio(KD) shows the condition of vegetation coverage. It also indicats the destruction of forest soil erosion.By comparing the contents of arbor and shrub phytoliths and herbaceous phytoliths from Tinchuan and Jixiang profiles, arbor and shrub phytoliths is most abundant in profile surface, which means sponge spicules percentage in the surface layer increased significantly, climate got warmer significantly, and human activity enhanced. This is consistent with geochemistry and granularity analysis. Loss on Ignition of the profile decreases from the bottom up, lowest in 4-5cm, which has some contact with climate change and land utilization type change.The four indexes show the climate process of Changbai mountain since the Ming and qing dynasties. 1580~1750, cold and dry, drought and flood alternately. 1750~1900, dry and cold. 1900~1960, alternating wet and dry changes in temperature. 1960~now, wet and warm. And the result is consistent with historical literature record. 1580~1750, Lia’s cold stage, less human interfered in the study area. 1750~1900, human migranted in and vegetation coverage rate declined. 1900~1960, reclaim wasteland, serious soil erosion. 1960~now, human deforestation, soil erosion more serious. So it’s visible that the land use/cover changes is associated with climate changes, and embodied in peat sediment. |
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