Impacts of Spatially Heterogeneous Nitrogen to Grazer Distribution and Activity: Effects on Ecosystem Function in Tallgrass Prairie

在世界各地的草原上，放牧者在最近放牧活动和火灾之间的相互作用中，遇到了整个景观中高度不同的食物质量。该研究项目探讨(A)植物氮和饲草质量的这种空间变异性如何决定北美草原系统中食草动物的分布；(B)放牧活动是否以及如何通过改变生境、营养循环和动植物生物多样性来调节各种其他草原生态系统过程。该项目的主要假设是，火-牧相互作用产生的饲料(蛋白质)中的氮含量和栖息地的物理结构决定了野牛对景观的利用，从而增加了栖息地的异质性。这反过来又会影响其他重要的食草动物，从而影响生态系统功能和生物多样性。研究将在堪萨斯州东部Konza Prairie生物站的高草草原上进行，方法是跟踪野牛的放牧模式与绘制的牧草质量之间的关系，并将使用新的遥感技术进行测量。野牛的活动将使用GPS(全球定位系统)项圈进行跟踪，以提供全年每小时的准确野牛位置。这些数据随后将利用地理信息系统(地理信息系统)技术绘制出饲草氮浓度在精细和粗略空间尺度上的分布情况。植物群落和主要昆虫食草动物(蝗虫)对野牛放牧活动引起的栖息地变化的反应将通过比较实地对利用该地点过去的研究活动和新发现制定的预定预测的反应来评估。此外，栖息地结构和饲料质量对野牛觅食活动和蝗虫多样性和丰度的作用将通过两个独立操纵氮肥和植被高度的大型田间试验来评估。最终，这项研究将评估野牛放牧和火灾干扰下生境异质性的产生和维持，评估其在草原生态系统功能中的作用，并有助于理解世界范围内的放牧系统。拟议的研究结果将立即应用于北美和全球常见的重要经济放牧系统，并为保护世界各地的本土食草动物及其栖息地提供基本的科学基础。该项目的成果将编成正式的网上教育模块，分发给不同的受众，包括学校系统、广大公众、推广方案和保护组织。将为土地管理人员开发和赞助讲习班和网上材料，以解释遥感、地理信息系统和其他技术的前景，这些技术可能有助于管理和养护放牧系统，并提供这些生态系统生态组成部分亟需的摘要。该项目还将促进研究生和本科生的研究培训，并为中学科学教师提供急需的研究机会；将特别鼓励科学方面代表性不足的群体的学生和教师参加。来自堪萨斯州学校系统的一名高中生物教师已经被招募到该项目中，该学校系统中低收入家庭和高流动性的军人家庭所占比例很高。

In grasslands worldwide, grazers encounter highly variable food quality across the landscape in response to recent interactions between grazing activity and fire. This research project examines (a) how such spatial variability in plant nitrogen and forage quality determines the distribution of herbivore grazers in a North American grassland system; and (b) if and how grazing activity then regulates a variety of other grassland ecosystem processes by altering habitats, nutrient cycling and the biodiversity of plants and animals. The overarching hypothesis of this project is that nitrogen content in forage (protein) and physical structure of the habitat resulting from fire-grazing interactions determines landscape use by bison, thereby increasing habitat heterogeneity. This, in turn, affects other important herbivores and thus impacts ecosystem function and biodiversity. Research will be performed in a tallgrass prairie at Konza Prairie Biological Station in eastern Kansas by following patterns of bison grazing in relation to mapped forage quality, which will be measured using new remote sensing technology. Bison movement activity will be tracked using GPS (global positioning system) collars to provide precise bison locations every hour throughout the year. These data will then be mapped on to the distribution of forage nitrogen concentrations at fine and coarse spatial scales using GIS (geographic information system) technology. Responses by plant communities and dominant insect herbivores (grasshoppers) to habitat changes from bison grazing activity will be assessed by comparing field responses to predetermined predictions that were developed using past research activities at the site and new discoveries. In addition, the roles of habitat structure and forage quality to both bison feeding activity and the diversity and abundance of grasshoppers will be evaluated with two large field experiments that independently manipulate N-fertilization and vegetation height. Ultimately, this study will evaluate the creation and maintenance of habitat heterogeneity from disturbance by bison grazing and fire, assess its role in ecosystem functioning of grasslands, and contribute to the understanding of grazing systems worldwide.Results of proposed research will have immediate, practical application to economically important grazing systems commonly found throughout North America and across the globe, and provide basic scientific foundations for conserving native grazers and their habitats worldwide. Results of this project will be developed into formal web-based educational modules to be disseminated to multiple, diverse audiences, including school systems, the public at large, extension programs and conservation organizations. Workshops and web-based materials for land managers will be developed and sponsored to explain the promise of remote sensing, GIS and other technologies that could be helpful in managing and conserving grazing systems as well as provide critically needed summaries of the ecological components of these ecosystems. The project will also contribute to research training for graduate and undergraduate students as well as provide much needed exposure to research by secondary science teachers; students and teachers from groups underrepresented in science will be especially encouraged to participate. A high school biology teacher from a Kansas school system with a high proportion of low income families and highly mobile military families has been recruited to the project.