Collaborative Research: Assessing climate-biosphere linkages using Late Holocene records of climate variability and vegetation dynamics from the Brazilian Amazon and Savanna

合作研究：利用巴西亚马逊和稀树草原的全新世晚期气候变化和植被动态记录评估气候与生物圈的联系

• 批准号: 1602958
• 负责人: Lucas Silva
• 金额: $ 9.24万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-15 至 2016-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1602958&HistoricalAwards=false
• 关键词: Collaborative; Research; Assessing; climate; biosphere

This collaborative project aims to investigate the role of changes in the South American Summer Monsoon (SASM) intensity on forest-savanna biome shifts that occurred during the Late Holocene. Development of paleoclimate records from in and near the core of the monsoon region enables an assessment of the strength of the paleo-monsoon signal across the region.The researchers look to generate independent, yet co-located, records of past climate (speleothems) and vegetation (soil profiles) dynamics from the Brazilian Amazon and Cerrado (savanna), for which existing records are absent. Paleoclimate and ecological interpretations will be validated using cave monitoring and proxy system modeling.The researchers intend to evaluate the following questions: i) Do speleothem delta 18-Oxygen values reflect variations in SASM intensity, ii) Do variations in SASM intensity drive corresponding variation in local moisture conditions, iii) What was the nature and driver of Late Holocene variability in SASM intensity and local moisture conditions, and iv) how sensitive were biomes in vegetative transition zones to variability in SASM intensity and local moisture conditions. The project involves the monitoring of modern cave environments to evaluate speleothem delta 18-Oxygen values as a proxy of SASM intensity and speleothem trace element concentrations and Strontium isotope compositions as a proxy of local moisture conditions. The research will extend existing speleothem delta 18-Oxygen records of the last millennium from the Amazon and Cerrado further back in time and develop corresponding records of speleothem trace element and 87- Strontium /86-Strontium and soil organic matter delta 13-Carbon to assess the co-variability between regional monsoon intensity, local moisture conditions, and biome shifts.The project helps promote greater understanding of the SASM and strong collaboration with Brazilian scientists. The SASM is the most important source of rainfall to the region with great socio-economic and environmental relevance, including defining current ecosystem distribution and stability, hydroelectric production, and agriculture.

这个合作项目的目的是调查在南美洲夏季风（SASM）强度的变化对森林稀树草原生物群落的变化，发生在晚全新世的作用。 从季风区的核心和附近的古气候记录的发展，使整个地区的古季风信号的强度进行评估。研究人员希望产生独立的，但共同定位，过去的气候（洞穴）和植被（土壤剖面）动态记录从巴西亚马逊和塞拉多（稀树草原），其中现有的记录是缺席。将使用洞穴监测和代理系统建模来验证古气候和生态解释。研究人员打算评估以下问题：i）洞穴沉积物三角洲18-氧值是否反映了SASM强度的变化，ii）SASM强度的变化是否驱动了当地湿度条件的相应变化，iii）晚全新世SASM强度和当地湿度条件变化的性质和驱动因素是什么，和iv）植被过渡区的生物群落对SASM强度和当地湿度条件的变化有多敏感。该项目涉及监测现代洞穴环境，以评估洞穴沉积物三角洲18-氧值作为SASM强度的代表，以及洞穴沉积物微量元素浓度和锶同位素组成作为当地湿度条件的代表。 这项研究将扩展现有的洞穴沉积物三角洲18-氧记录的上一个千年从亚马逊和塞拉多进一步回到过去的时间，并制定相应的记录洞穴沉积物微量元素和87-锶/86-锶和土壤有机质三角洲13-碳，以评估区域季风强度，当地水分条件，该项目有助于促进对SASM的更深入了解以及与巴西科学家的密切合作。 SASM是该地区最重要的降雨源，具有很大的社会经济和环境相关性，包括确定当前生态系统的分布和稳定性，水力发电和农业。