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研究现代地表沉积物有机碳同位素与植被-气候的关系,对于重建过去气候变化过程有重要意义。然而,对于气候变化幅度大、生态环境脆弱的浑善达克沙地,尚缺少相关的研究。本研究对浑善达克沙地进行了全面采样,对42个地表样品进行了有机碳同位素分析。结果表明,浑善达克沙地表土有机碳同位素(δ~13C)介于-25.0‰~-19.4‰之间,平均为-22.2‰。通过两端元方法估算,研究区C_4生物量介于O-46%之间,平均为17.9%,与前人的C_4植被调查结果有很好的可比性。相关分析表明,C_4生物量与年降水量呈显著负相关关系,而与温度关系不大,这表明在该地区年均温差异较小的情况下,降水可能是控制C_4植物生物量的主要因素;另外,推测也可能是研究区C_3生物量的变化主导地表有机碳同位素的变化。建立的δ~13C-年降水量转换函数,预期可用于重建浑善达克沙地全新世降水量的变化。
Studying the relationship between organic carbon isotopes and vegetation-climate in modern surface sediments is of great significance to the reconstruction of past climate change. However, there is still a lack of relevant research on the Hunshandake Sandy Land where the climate change is large and the ecological environment is fragile. In this study, a comprehensive sampling of Hunshandake sandy land was conducted, and 42 surface samples were analyzed for their organic carbon isotopes. The results showed that the organic carbon isotope (δ ~ 13C) of the surface soil of Hunshandake sand land was between -25.0 ‰ and -19.4 ‰, averaging -22.2 ‰. Estimated by the two-terminal method, the biomass of C_4 in the study area was between 0 and 46% with an average of 17.9%, which was in good agreement with the findings of previous C_4 vegetation surveys. Correlation analysis showed that there was a significant negative correlation between C_4 biomass and annual precipitation but not with temperature, indicating that precipitation may be the main factor controlling C_4 plant biomass in the region with small annual difference in temperature In addition, it may be speculated that the change of biomass of C_3 in the study area may be the predominant variation of the surface organic carbon isotope. The established δ ~ 13C-annual precipitation conversion function is expected to be used to reconstruct the changes of Holocene precipitation in Hunshandake Sandy Land.