青藏高原东部高寒草甸区域相对花粉产量估算及其应用

Researches on the past vegetation succession and its relationship with paleoclimate provide an indispensable key to understand the response of vegetation to recent global warming, and to predict future vegetation change. Fossil pollen is the most important proxy for reconstructing the paleovegetation change. The relative pollen productivity is an important link to connect vegetation with pollen assemblage. A series of models have been proposed to estimate the relative pollen productivities of plants and then to apply them in paleovegetation reconstruction, including Extended R-value (ERV) model and Landscape Reconstruction Algorithm (LRA). In this project, we plan to investigate the modern pollen assemblages and vegetations in the alpine meadow region of eastern Tibetan Plateau, which is located in the Asian monsoon-margin region. Based on the detailed data of modern pollen assemblage and vegetation, we estimate the RPPs for key taxa of this region using ERV model. On the basis of RPPs estimation, LRA is applied to quantitatively simulate modern vegetation based on the modern pollen data. In turn, the reliability of LRA in the study region is tested by comparing the simulated vegetation with the actual ones. Then, a case study is provided on the application of LRA to reconstruct the Holocene vegetation succession at local scale in eastern Tibetan Plateau, based on the fossil pollen data deriving from a Holocene lacustrine/swampy core in the study region. Finally, based on the original and published fossil pollen data, the LRA is used to quantitatively reconstruct the spatio-temporal patterns of the Holocene vegetation in eastern Tibetan Plateau. This will be a new attempt for studying the mechanism of vegetational response to the Holocene climate change in eastern Tibetan Plateau.

研究过去植被对气候变化的响应为理解今天全球变暖背景下植被的响应机制提供参考，为预测未来植被变化提供依据。花粉化石是古生态研究中最重要的古植被代用指标。相对花粉产量是客观反映花粉与植被数量关系的关键环节，目前国际上已形成一套从估算相对花粉产量，到将其用于古植被定量重建的理论模型，包括ERV模型及其衍生模型景观重建算法。本项目拟在青藏高原东部高寒草甸区域系统开展现代花粉组合和植被调查，利用ERV模型估算该区域植物的相对花粉产量。以此为基础，利用景观重建算法基于现代花粉数据模拟现代植被，通过与实际植被对比检验景观重建算法的有效性。然后，基于研究区域典型钻孔花粉分析结果利用景观重建算法定量重建当地全新世植被演替过程，并分析古植被变化的机制。最后，在更大空间尺度上整合已有的花粉化石记录，利用景观重建算法定量分析研究区域全新世以来的植被时空格局变化，探讨该区域植被对全新世气候变化的响应机制。

研究地质历史时期青藏高原植被对气候变化的响应规律能为理解现今全球气候变暖背景下高寒植被的变化机制、及预测未来气候变化情景下的植被响应提供可靠依据。花粉化石是研究过去植被变化的重要代用指标，相对花粉产量是校正花粉与植被数量关系的关键参数。本项目在青藏高原东部高寒草甸区域系统开展现代花粉组合与植被调查，分析现代花粉与植被的关系，用ERV模型估算出该区域主要植物类群的相对花粉产量，并检验其可靠性；基于新获得的相对花粉产量数据，在高寒草甸区域典型地区若尔盖盆地，整合不同点位的全新世化石花粉序列，用景观重建算法恢复若尔盖盆地全新世植被组成的变化过程，并以此分析了当地植物多样性变化，探讨气候变化和人类活动对青藏高原东部高寒植被的影响；在更大空间尺度上整合高寒草甸区域已有的花粉化石记录，利用景观重建算法定量分析该区域全新世的植被空间格局变化。研究结果为今后在青藏高原高寒草甸区域通过花粉化石序列定量重建古植被演替提供关键参数，为青藏高原古气候模拟及高寒植被保护和恢复提供科学依据。