Long Term Ecological Research-Shortgrass Steppe

摘要（SGS LTER更新建议）短草草原（SGS） LTER自1982年开始运行。三个问题指导其工作：(1)什么因素在空间和时间上调节生态结构和功能？(2)调节生物与非生物组分的结构、功能和耦合的因子在时空上是如何变化的？(3)决定结构和功能影响因素变化脆弱性的阈值是什么？该概念框架认为，生态结构和功能受气候、自然干扰、地理、人类使用和生物相互作用的支配。SGS的工作分为三个主题领域：种群动态（植物和异养生物）、生物地球化学和陆地-大气相互作用。干扰是如此重要，以至于它们嵌入到每个主题领域。除了继续进行长期实验外，SGS还将针对问题3展开新的研究。在种群动态方面，布蒂洛瓦草（boueloua gracilis）对生物量和净初级生产量的贡献最大，是过去大多数研究的重点。对占NPP一小部分的多刺仙人掌（Opuntia polyacantha）进行新的长期研究；它的刺状生长形式为其他物种提供了保护，因此在放牧中可能有很大的作用。尽管SGS已被证明对入侵植物具有相当的抵抗力，但引入能够成功入侵SGS的物种是不可避免的。因此，研究具有不同生活史属性的植物入侵的可能性，并进行调查以发现新的入侵。在区系动态方面，小型哺乳动物同时反映和影响着SGS生态系统的结构和功能。将继续进行长期研究，追踪小型哺乳动物的种群、资源和捕食者。新的研究将强调黑尾草原土拨鼠（Cynomys ludovicianus）的动态及其对生物多样性和生态系统功能的影响。曾经数量众多的草原土拨鼠现在被列入濒危物种法案的候选名单。在生物地球化学方面，SGS认为生物地球化学过程是生物成分和负责碳和养分通量的过程的综合功能：初级生产、分解、风化、矿化和微量气体通量。将继续研究生物地球化学的变化作为气候控制的作用，并将开始评估地质（质地）和地形控制以及氮预算的新研究。关于陆地-大气相互作用，主要关注的过程是水、能量和气体通量。在SGS LTER上已经发生并将继续发生的最重要的变化之一是土地利用变化，将根据人类土地利用、生物反应和大气过程在地方到区域尺度上的相互作用来评估土地利用变化。SGS在模拟分析方面投入了大量资金，每个主题领域都有一个模拟组件。模型将继续用于综合研究领域内和跨研究领域的长期数据。下一个筹资周期将出版一份新的综合卷。最后，数据管理支持SGS研究并有助于生态信息学。将继续与联邦土地管理机构、非政府组织和感兴趣的公众建立新的互动。通过使用补充资金，SGS将通过学生辅导、课程开发、教师专业发展、社区合作伙伴关系和教育研究，将sLTER的重点放在K-12和社区外展上。

Abstract (SGS LTER Renewal Proposal)The shortgrass steppe (SGS) LTER has been in operation since 1982. Three questions guide its work: (1) What factors regulate ecological structure and function over space and time? (2) How do factors that regulate structure and function and coupling of biotic and abiotic components vary spatially and temporally? (3) What are the thresholds that determine the vulnerability to changes in the factors influencing structure and function? The conceptual framework asserts that ecological structure and function are governed by climate, natural disturbance, physiography, human use, and biotic interactions. SGS work is divided into three topic areas, population dynamics (plants and heterotrophs), biogeochemistry, and land-atmosphere interactions. Disturbances are of such importance that they are embedded in each topic area. In addition to continuing long-term experiments, SGS will initiate new studies that primarily focus on Question 3. In the area of population dynamics, one grass species, Bouteloua gracilis, contributes most to biomass and net primary production (NPP) and has been the focus of most past work. New long-term studies of Opuntia polyacantha (prickly-pear cactus), a species that makes up a small proportion of NPP, will be initiated; its spiny growth form affords protection to other species and therefore may have a large effect under cattle grazing. Even though the SGS has proven quite resistant to invasive plants, the introduction of species that can successfully invade the SGS is inevitable. So the potential for invasion by plants with different life history attributes will be studied and surveys conducted to detect new invasions. In the area of faunal dynamics, small mammals simultaneously reflect and affect both the structure and function of the SGS ecosystem. Long-term studies will be continued that track small mammal populations, their resources and predators. New research will emphasize the dynamics of the black-tailed prairie dog (Cynomys ludovicianus) and its effects on biological diversity and ecosystem function. The once abundant prairie dog is now a candidate for listing under the Endangered Species Act. Under biogeochemistry, SGS conceives of biogeochemical processes as an integrated function of biotic components and those processes responsible for carbon and nutrient fluxes: primary production, decomposition, weathering, mineralization, and trace gas flux. Variations in biogeochemistry will continue to be studied as a function of climatic controls, and new studies that evaluate geologic (textural) and topographic controls, and the N budget will be initiated.Regarding land-atmosphere interactions, the processes of primary concern are water, energy, and gaseous fluxes. One of the most important alterations that has occurred and continues to occur on the SGS LTER is land-use change, which will be evaluated in terms of the interactions among human land use, biotic responses, and atmospheric processes at local to regional scales. The SGS has a major investment in simulation analysis, and each of topic areas has a simulation component. Models will continue to be used for synthesizing long-term data both within and across research areas. A new synthesis volume will be published during the next funding cycle.Finally, data management supports SGS research and contributes to ecoinformatics. The building of new interactions with federal land management agencies, NGO's, and the interested public will be continued. Through the use of supplemental funding, SGS will focus its sLTER on K-12 and community outreach through student mentoring, curriculum development, teacher professional development, community partnerships, and education research.