摘要
陆地生态系统古碳储量演化历史既是理解过去区域碳循环过程的基础, 也是预测未来陆地碳库变化趋势的重要参照。以往由于实测记录的缺乏和现代碳循环模型应用的局限, 难于实现过去陆地碳库的准确重建。本研究通过地质时期86个点位的孢粉记录与古碳循环模型模拟的结合, 在定量化重建全新世渭河流域古气候参数空间格局的基础上, 模拟了自然植被时空演化过程及其陆地生态系统碳储量变化。结果表明, 全新世早期到中期, 流域森林面积覆盖度由34%增至63%, 导致陆地生态系统碳储量从2.48PgC增至3.40PgC;全新世中期到晚期, 流域森林面积覆盖度降至20%, 陆地生态系统碳库储量随之减少了1.03PgC。空间上, 流域碳密度变化主要受控于植被类型的分布, 后者又与地貌条件密切相关。全新世中期全球增温情形下渭河流域森林植被大面积扩张和碳储量显著增加的结果, 预示着未来全球变暖背景下该流域陆地生态系统具有较强的碳汇潜力。
Estimation of paleo terrestrial ecosystem carbon storage is crucial for understanding the process of past regional carbon cycle, and it is also an important reference for predicting the change of terrestrial ecosystem carbon pools in the future. However, it is still difficult to make such quantitative estimations due to the lack of observed carbon data in the past, and the direct application of modern carbon cycle models to the past is often limited by their complex inputs. Wei River valley(33.5°~37.5°N and 103.5°~110.5°E) locates in the monsoonal boundary areas, the vegetation evolutions in the valley are sensitive to climate change, and also have been significantly disturbed by human activities.In this study, based on 86 pollen records, biomization method, inverse distance spatial extrapolation technology and paleo carbon cycle model(PCM), the spatially continuous distributions of Holocene climatic variables across the Wei River valley have been reconstructed, which have been further used to force PCM to simulate the regional Holocene vegetation evolutions and corresponding changes of terrestrial ecosystem carbon storages. The reliability of simulation has been validated by well consistency between simulated and reconstructed vegetation types of pollen sites inside the valley during the Holocene.The results showed that, from the Early to the Middle Holocene, the forest cover in the valley has increased from 34% to 63%, which has induced the growth of terrestrial ecosystem carbon storage from 2.48PgC to 3.40PgC. From the middle to the Late Holocene, the forest cover has decreased by more than 40% and the corresponding carbon loss in terrestrial ecosystem has been about 1.03PgC. The spatial variations of ecosystem carbon density have been correlated with the distributions of forest vegetation, which were further related to different landform conditions, because the vegetation and soil carbon densities in forest ecosystems were both significantly higher than that of grassland ecosystems, and the expansion and contraction of forests usually occurred in the mountain and valley areas(e.g. the region between Liupan and Ziwu mountains). In comparison with simulated terrestrial carbon storages during 6~5kaB.P., 1~0kaB.P. and modern observed carbon storage in the valley, the contribution of natural vegetation evolution to the carbon loss from the Middle Holocene to present was about 72.5%. Because the Middle Holocene can be taken as the reference of future global warming due to its higher temperature condition than present, the significant expansion of forest vegetation and increase of terrestrial ecosystem carbon storage in the Wei River valley during the period, suggest the terrestrial ecosystem in the valley would have high carbon absorption potential in the future.
作者
于严严
吴海斌
李琴
孙爱芝
罗运利
YU Yanyan;WU Haibin;LI Qin;SUN Aizhi;LUO Yunli(Key Laboratory of Cenozoic Geology and Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029;CAS Center for Excellence in Life and Paleoenvironment,Beijing 100044;University of Chinese Academy of Sciences,Beijing 100049;School of Geography,Liaoning Normal University,Dalian 116029,Liaoning;Institute of Botany,Chinese Academy of Sciences,Beijing 100093)
出处
《第四纪研究》
CAS
CSCD
北大核心
2023年第2期345-355,共11页
Quaternary Sciences
基金
国家重点研发计划项目(批准号:2020YFA0607700)
国家自然科学基金项目(批准号:41888101、41877441和42177180)
中国科学院(B类)战略性先导科技专项项目(批准号:XDB26000000)共同资助。
关键词
古碳循环
植被格局
全新世
孢粉记录
植被反演
碳循环模型
paleocarbon cycle
vegetation pattern
Holocene
pollen records
inverse vegetation approach
carbon cycle model
作者简介
于严严,女,42岁,副研究员/博士,第四纪地质学专业,E-mail:yyy@mail.iggcas.ac.cn。
