DISSERTATION RESEARCH: Scaling Plant Physiology to Ecosystem Ecology: Assessing the Role of the Plant Community in Preventing Nitrogen Losses Following Fire

DEB-1601279 Wright，Justin P.，杜克大学：论文研究：将植物生理学扩展到生态系统生态学：评估植物群落在防止火灾后氮素损失中的作用。土壤资源的可用性，如养分和水，影响局部和全球范围内植物的多样性。火灾等干扰会极大地改变植物的资源可获得性。例如，经历频繁火灾的生态系统在火灾发生后也会经历氮素可获得性激增。尽管氮是所有植物的重要资源，但没有被植物捕获的氮可能会被冲走，并造成溪流和湖泊的污染。因此，重要的是要了解如果氮素有效性发生变化，植物多样性可能会如何变化，以及随后植物群落保留氮素的能力可能也会如何变化。研究人员将研究，与没有经历过氮脉冲的植物群落相比，经历过频繁氮脉冲的植物群落是否能够更好地捕获氮并防止其离开生态系统。这项研究将有助于预测植物群落如何对氮素有效性的变化做出反应，以及氮素的滞留和损失模式如何受到火灾频率的影响。作为这个项目的一部分，一名本科生将获得野外生态学和实验室化学分析的实践经验。此外，研究人员将开展教学活动，以提高本科生对局部和全球范围内N自行车的理解。这项研究的数据将被添加到一个用于估计全球碳循环的数据库中。这项研究的结果将在同行评议的期刊和国家会议上传播。该项目是对温室研究中确定的种间脉冲氮同化差异模式的经验实地测试。研究人员将在具有不同历史火灾频率(年度燃烧或灭火)的地点进行同位素分析，追踪氮在长叶松林中不同生态系统隔间的命运。研究人员将测量储存在微生物生物量、优势植物地上和地下生物量以及大量土壤中的同位素数量。通过比较每年燃烧或灭火制度下不同地点不同隔间储存的氮量，他们将评估暴露在频繁氮脉冲下的植物群落在多大程度上适应捕捉这种短暂的资源。此外，他们将测试这些种间捕获脉冲氮能力的差异是否会扩大到影响田间生态系统水平的氮保留模式。研究人员预测，与火灾抑制地点相比，群落组成的变化有利于适应吸收短暂氮素的物种，将导致频繁燃烧地点的氮素滞留增加。

DEB-1601279 Wright, Justin P., Duke University: DISSERTATION RESEARCH: Scaling Plant Physiology to Ecosystem Ecology: Assessing the Role of the Plant Community in Preventing Nitrogen Losses Following Fire.The availability of soil resources, such as nutrients and water, influence the diversity of plants at local and global scales. Disturbances such as fires can drastically change resource availability to plants. For example, ecosystems that experience frequent fires also experience surges of nitrogen availability after the fire. Although nitrogen is a crucial resource for all plants, nitrogen not captured by plants can be washed away and contribute to the pollution of streams and lakes. As such, it is important to understand how plant diversity might change if nitrogen availability changes, and subsequently how the ability of the plant community to retain nitrogen might also change. Investigators will examine whether plant communities that have experienced frequent pulses of nitrogen are better able to capture nitrogen and prevent it from leaving the ecosystem than are plant communities that have not experienced nitrogen pulses. This research will help to predict how plant communities respond to changes in nitrogen availability, and how patterns of nitrogen retention and loss are affected by fire frequency. As part of this project, one undergraduate student will gain hands-on experience in field ecology and laboratory chemical analyses. In addition, the investigators will develop teaching activities to improve understanding of N cycling at local and global scales by undergraduate students. Data from this study will be added to a database used to estimate the global carbon cycle. The findings of the study will be disseminated in peer-reviewed journals and at national conferences.This project is an empirical field test of patterns identified in greenhouse studies of interspecific differences in pulsed nitrogen assimilation. The researchers will trace the fate of nitrogen into different ecosystem compartments in a longleaf pine (Pinus palustris) forest, using isotope analysis in sites with contrasting historical fire frequencies (annual burns or fire suppression). Researchers will measure the amount of isotope stored in microbial biomass, aboveground and belowground biomass of dominant plant species, and the bulk soil pool. By comparing the amount of nitrogen stored in different compartments between sites under annual burn or fire suppression regimes, they will assess the extent to which plant communities exposed to frequent nitrogen pulses are adapted to capturing this ephemeral resource. Further, they will test whether these interspecific differences in the capacity to capture pulsed nitrogen scale up to influence ecosystem-level nitrogen retention patterns in the field. The researchers predict that shifts in community composition favoring species adapted to assimilating ephemeral nitrogen will result in increased nitrogen retention in frequently burned sites, as compared to fire-suppressed sites.