RAPID: Plant Species Effects on Rapid Stabilization of Nitrogen in Soil Organic Matter of Mangrove Ecosystems at Risk from the BP Deepwater Horizon Oil Spill

RAPID：植物物种对受 BP 深水地平线漏油威胁的红树林生态系统土壤有机质中氮快速稳定的影响

• 批准号: 1059236
• 负责人: David Lewis
• 金额: $ 16万
• 依托单位: University of South Florida
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1059236&HistoricalAwards=false
• 关键词: RAPID; Plant; Species; Effects; Rapid

This is a Rapid Research Response grant in relation to the BP Deepwater Horizon oil spill. Nitrogen (N) is an essential element for life. Because it is scarce in a biologically usable form, organisms are sensitive to increases in N availability. Human activities have increased the cycling of N in the biosphere, galvanizing interest in the ability of ecosystems to retain N. Nitrogen is effectively stored by the decaying remnants of vegetation, animals, and microorganisms - collectively known as soil organic matter, or SOM. The research described here investigates whether SOM can immobilize N quickly - within minutes to weeks - after N is first introduced to the soil. This research will test the hypotheses (1) that SOM quickly immobilizes N in the stable fraction, which is the subset of SOM that takes years to decompose, and (2) whether immobilization happens at different rates in different forests, which have different kinds of SOM. This research is conducted in intertidal, mangrove forests along the coast of west-central Florida near Tampa Bay, which are at risk for exposure to oil deposition from the BP Deepwater Horizon oil spill. In each forest, investigators will collect soil cores that are 15 cm deep, and inject N as a bio-available form into the cores. After a measured reaction time (hours to weeks), the amount of N incorporated into the stable SOM will be determined. This will allow scientists to calculate the rate at which N gets immobilized in stable SOM. One goal of this project is to determine whether N immobilization in stable SOM differs among forests, so the characteristics of each forest will be described in two ways: with ground surveys and with remote sensing from satellites. The ground surveys will be conducted following standard procedures of the U.S. Forest Service: identifying the species of each tree, measuring several dimensions of tree size (height, girth, canopy cover), identifying trees that have died or newly germinated, and analyzing the chemistry of leaf tissues. The remote sensing will use multispectral and hyperspectral imaging. Spectral signatures, which are the combinations of reflected and absorbed light across the light spectrum, will reveal tree size and the amount and chemistry of foliage. The hypotheses of this project will be supported if scientists discover that N is, indeed, quickly immobilized in stable SOM, and that the rate of N immobilization differs among forests because of difference in the forest characteristics. As oil moves beyond the northern Gulf, it may put Florida Peninsula's western coastline at risk. Oil can affect the functioning of these mangrove ecosystems and alter the interaction between N and SOM in several ways. Not only is oil toxic to plants and soil organisms, crude oil is a source of N and organic matter (hydrocarbons) in its own right, potentially upsetting the pre-existing balance. Understanding baseline conditions in the dynamics of N and SOM mandates that this research be conducted now. In roughly the last 80 years, food and energy production by humans have tripled the amount of biologically usable N circulating through the biosphere. The ecological consequences have been profound, including increases in atmospheric greenhouse gas and smog concentrations, shifts in the composition of forest plants, and conspicuous algal blooms and de-oxygenation in aquatic habitats like the Gulf of Mexico. This research directly elucidates a mechanism for preventing such adverse environmental effects of accelerated N cycling. Academic and public resource agencies will be brought in closer contact, as researchers from the University of South Florida and the University of Florida interact with park and property managers at the mangrove forest sites, and with Forest Service employees. The research also will afford graduate students and undergraduate protégés the opportunity to respond to the concerns of a diverse and engaged citizenry of a large urban area. Finally, the use of remote sensing in the project may lead to tools for rapidly quantifying the impacts of disturbance and targeting restoration effects across west-central Florida's vast and otherwise intractable mangrove forest inventory.

这是一项与 BP 深水地平线漏油事件相关的快速研究响应补助金。 氮（N）是生命的必需元素。由于生物可用形式的氮很稀缺，因此生物体对氮可用性的增加很敏感。人类活动增加了生物圈中氮的循环，激发了人们对生态系统保留氮能力的兴趣。氮被植被、动物和微生物的腐烂残余物有效储存——统称为土壤有机质，或 SOM。这里描述的研究调查了在氮首次引入土壤后，SOM 是否可以在几分钟到几周内快速固定氮。这项研究将检验以下假设：(1) SOM 快速将氮固定在稳定部分，稳定部分是 SOM 的子集，需要数年时间才能分解；(2) 在具有不同类型 SOM 的不同森林中，固定是否以不同的速率发生。这项研究是在佛罗里达州中西部坦帕湾附近海岸的潮间带红树林中进行的，这些森林面临着暴露于英国石油公司深水地平线漏油事件的石油沉积的风险。在每片森林中，研究人员将收集 15 厘米深的土壤核心，并将生物可利用形式的氮注入核心中。经过测量的反应时间（数小时至数周）后，将确定纳入稳定 SOM 的 N 量。这将使科学家能够计算 N 固定在稳定 SOM 中的速率。该项目的目标之一是确定稳定 SOM 中的氮固定在不同森林之间是否存在差异，因此将通过两种方式描述每个森林的特征：地面调查和卫星遥感。地面调查将按照美国林业局的标准程序进行：识别每棵树的物种，测量树木尺寸的几个维度（高度、周长、树冠覆盖度），识别已死亡或新发芽的树木，并分析叶子组织的化学成分。遥感将使用多光谱和高光谱成像。光谱特征是整个光谱中反射光和吸收光的组合，将揭示树木的大小以及树叶的数量和化学成分。如果科学家发现氮确实快速固定在稳定的 SOM 中，并且由于森林特征的不同，森林之间的氮固定率也不同，那么该项目的假设将得到支持。 随着石油移出北部湾，可能会使佛罗里达半岛的西海岸线面临风险。石油可以影响这些红树林生态系统的功能，并以多种方式改变氮和有机质之间的相互作用。石油不仅对植物和土壤生物有毒，而且原油本身就是氮和有机物（碳氢化合物）的来源，有可能破坏预先存在的平衡。了解 N 和 SOM 动态的基线条件要求立即进行这项研究。大约在过去 80 年里，人类生产的食物和能源使生物圈中循环的生物可用氮量增加了两倍。其生态后果是深远的，包括大气中温室气体和烟雾浓度的增加、森林植物成分的变化以及墨西哥湾等水生栖息地的明显藻华和缺氧。这项研究直接阐明了防止加速氮循环对环境产生不利影响的机制。 南佛罗里达大学和佛罗里达大学的研究人员将与红树林遗址的公园和财产管理人员以及林务局员工进行互动，学术和公共资源机构将建立更密切的联系。该研究还将为研究生和本科生提供机会来回应大城市地区多元化和积极参与的公民的担忧。最后，该项目中遥感的使用可能会带来快速量化干扰影响的工具，并针对佛罗里达州中西部广阔且难以处理的红树林资源的恢复效果。