Mangrove Paleoecological Responses During Holocene Sea Level Changes: A Multiproxy Aapproach

全新世海平面变化期间红树林古生态响应：多代理方法

• 批准号: 0533974
• 负责人: Matthew Wooller
• 金额: --
• 依托单位: University of Alaska Fairbanks Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-07-15 至 2009-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0533974&HistoricalAwards=false
• 关键词: Mangrove; Paleoecological; Responses; During; Holocene

Mangroves (coastal marine forests composed of a number of different tree species) exist in the tropics and sub-tropics at the transition between the ocean and terrestrial environment; a setting that is particularly sensitive to environmental changes such as sea-level rise. Many coastal environments depend on mangrove habitats to reduce erosion, buffer the influence of hurricanes and provide habitats for marine organisms. There is concern about the response of mangroves to future sea-level rise scenarios. However, laboratory and field experiments involving mangroves provide a limited temporal and spatial perspective of mangrove responses to environmental change. Our proposed research presents a novel approach to study past mangrove responses to environmental change throughout the Holocene (the last ~10,000 years), a period during which sea-level is known to have risen. The continuous deposits of mangrove peat present in Belize are the largest in the world and provide an exceptional resource to study past mangrove ecosystems over this period. A number of peat cores have already been collected and will be analyzed during this proposed project. We propose analyzing cores from three different sites to develop a robust picture of regional past mangrove ecology. One core (~8 m in depth) is from Twin Cays and a second core (~8 m in depth) is from Tobacco Range. These sites are ~12 km off of the mainland coast of Belize and are therefore less liable to be influenced by mainland tropical plant species. In addition, by analyzing a core (~6 m in depth) taken from coastal mangroves on the mainland, we will be able to compare and contrast coastal and island mangrove responses to Holocene sea-level changes. Ecosystem changes will be established by studying multiple lines of evidence (multiple proxies of the past vegetation) preserved in these peat cores, which are dated using radiocarbon dating. Peat cores will be analyzed for proxies that include counts of fossil pollen to track changes in vegetation composition, together with bulk and compound specific stable isotopic (C and N) techniques that will monitor physiological changes in mangroves with time. By analyzing a suite of proxies at each site, we will be able to develop detailed histories describing important aspects of these ecosystems, including factors such as species composition, plant morphology and structure, nutrient status and availability, peat accumulation rates, and physiological stress. By analyzing multiple sites, and multiple cores within a site, we will be able to distinguish between site-specific and regional trends, which will allow us to determine a robust assessment of overall ecosystem changes. In turn, these data will be compared with the framework of Holocene sea-level change for the region. We believe that our sites are among the best available to develop long-term records of mangrove ecosystems. Ultimately, knowledge of how these ecosystems responded to past environmental change is important in assessing how tropical ecosystems will function in response to future environmental changes.

红树林（由许多不同树种组成的沿海海洋森林）存在于海洋和陆地环境之间的热带和亚热带过渡地带;这种环境对海平面上升等环境变化特别敏感。许多沿海环境依靠红树林生境来减少侵蚀，缓冲飓风的影响，并为海洋生物提供生境。人们对红树林对未来海平面上升的反应感到关切。 然而，涉及红树林的实验室和野外实验为红树林对环境变化的响应提供了有限的时间和空间视角。我们提出的研究提出了一种新的方法来研究过去的红树林对整个全新世（过去~10,000年）环境变化的反应，在此期间，海平面上升。伯利兹的红树林泥炭的连续沉积是世界上最大的，为研究这一时期过去的红树林生态系统提供了特殊的资源。已经收集了一些泥炭芯，并将在本拟议项目期间进行分析。我们建议分析从三个不同的网站核心开发一个强大的图片区域过去的红树林生态。 一个岩芯（约8米深）来自Twin Cays，另一个岩芯（约8米深）来自Tobacco Range。这些地点距离伯利兹大陆海岸约12公里，因此不易受到大陆热带植物物种的影响。此外，通过分析取自大陆沿海红树林的岩心（深度约6米），我们将能够比较和对比沿海和岛屿红树林对全新世海平面变化的响应。生态系统的变化将通过研究保存在这些泥炭芯中的多条证据线（过去植被的多个代理）来确定，这些泥炭芯使用放射性碳测年法进行测年。将分析泥炭芯的替代物，包括化石花粉计数，以跟踪植被组成的变化，以及散装和复合特定的稳定同位素（C和N）技术，将监测红树林随时间的生理变化。通过分析每个站点的一套代理，我们将能够开发详细的历史，描述这些生态系统的重要方面，包括物种组成，植物形态和结构，营养状况和可用性，泥炭积累率和生理压力等因素。 通过分析多个站点和站点内的多个核心，我们将能够区分特定站点和区域趋势，这将使我们能够确定对整体生态系统变化的可靠评估。 反过来，这些数据将与该地区全新世海平面变化的框架进行比较。 我们相信，我们的网站是最好的发展长期记录的红树林生态系统。 最后，了解这些生态系统如何应对过去的环境变化对于评估热带生态系统如何应对未来的环境变化至关重要。