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

这是一项与BP深水地平线石油泄漏有关的快速研究反应赠款。 氮（N）是生命的必需元素。因为它是稀缺的生物可用的形式，生物体是敏感的N可用性的增加。人类活动增加了氮在生物圈中的循环，激发了人们对生态系统保持氮的能力的兴趣。氮被植物、动物和微生物的腐烂残余物有效地储存起来--统称为土壤有机质，或SOM。这里描述的研究调查了SOM是否可以在N首次引入土壤后快速-在几分钟到几周内-吸收N。本研究将验证以下假设：（1）SOM快速固定N在稳定部分中，这是SOM的子集，需要数年才能分解，（2）固定是否在不同的森林中以不同的速度发生，这具有不同的SOM。这项研究是在坦帕湾附近的佛罗里达中西部海岸沿着潮间带的红树林中进行的，这些红树林有暴露于英国石油公司深水地平线漏油事件造成的石油沉积的风险。在每片森林中，调查人员将收集15厘米深的土壤芯，并将N作为生物有效形式注入芯中。在测量的反应时间（小时至数周）后，将确定掺入稳定SOM中的N的量。这将使科学家能够计算出N在稳定的SOM中固定的速率。该项目的一个目标是确定是否N固定在稳定的SOM不同的森林，每个森林的特点将被描述为两种方式：地面调查和卫星遥感。地面调查将按照美国林务局的标准程序进行：识别每棵树的物种，测量树木大小的几个维度（高度，周长，树冠覆盖率），识别已经死亡或新发芽的树木，并分析叶组织的化学成分。遥感将使用多光谱和超光谱成像。光谱特征是整个光谱中反射和吸收光的组合，将揭示树木的大小以及树叶的数量和化学成分。如果科学家们发现，N是，确实，迅速固定在稳定的SOM，和N固定率不同的森林，因为不同的森林特征，该项目的假设将得到支持。 随着石油移出北方海湾，可能会使佛罗里达半岛的西海岸线处于危险之中。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N和SOM之间的相互作用。石油不仅对植物和土壤生物有毒，原油本身也是氮和有机物（碳氢化合物）的来源，可能会破坏原有的平衡。了解基线条件下的动态N和SOM的任务，这项研究现在进行。在过去的大约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。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，森林植物组成的变化，以及墨西哥湾等水生栖息地明显的藻类水华和脱氧。这项研究直接阐明了一种机制，防止这种不利的环境影响加速N循环。 学术和公共资源机构将进行更密切的接触，因为来自南佛罗里达大学和佛罗里达大学的研究人员将与红树林森林遗址的公园和物业管理人员以及林务局的员工进行互动。该研究还将为研究生和本科生提供机会，以回应一个大城市地区的多元化和参与公民的关注。最后，在该项目中使用遥感可能会导致工具，快速量化的干扰和目标的恢复效果，在中西部佛罗里达的广大和其他棘手的红树林森林库存的影响。

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.