SGS-LTER Ecosystem Stress Area - long-term density dataset following nutrient enrichment stress on the Central Plains Experimental Range in Nunn, Colorado, USA 1975-2011, ARS Study Number 3

This data package was produced by researchers working on the Shortgrass Steppe Long Term Ecological Research (SGS-LTER) Project, administered at Colorado State University. Long-term datasets and background information (proposals, reports, photographs, etc.) on the SGS-LTER project are contained in a comprehensive project collection within the Digital Collections of Colorado (http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429). The data table and associated metadata document, which is generated in Ecological Metadata Language, may be available through other repositories serving the ecological research community and represent components of the larger SGS-LTER project collection.
Water, nitrogen, and water-plus-nitrogen at levels beyond the range normally experience by shortgrass steppe communities were applied from 1971 through 1975, plant densities were sampled through 1977, and then sampling resumed in 1982, with sampling frequencies changing from annually to every other year. The initial sampling from 1970 to 1974 showed that the water and water plus nitrogen treatments had the strongest effect on plant community structure, both treatments increased biomass, and exotic weed species were noted on the water plus nitrogen treatment. Later sampling from 1982 to 1991 showed a ten-fold increase in exotic weed species on the water plus nitrogen plots as compared to the controls (Milchunas and Lauenroth 1995), a community change that has persisted on this site due to a chronic elevation of soil nitrogen caused by a plant tissue/soil organic matter feedback mechanism (Vinton and Burke 1995). In 1998, Six new treatments were superimposed on the historic study site. The six new treatments were: control, sugar, lignin, sawdust, lignin and sugar, and sawdust and sugar.In 2010, plots will be sampled every 5 years. Our objective in this study is to examine how plant communities change through time and explore implications of these changes for monitoring potentially stressed ecosystems. Additional information and referenced materials can be found: http://hdl.handle.net/10217/83317. Resources in this dataset:Resource Title: Website Pointer to html file. File Name: Web Page, url: https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-sgs&identifier=520 Webpage with information and links to data files for download

本数据包由致力于短草草原长期生态研究（SGS-LTER）项目的研究人员所制作，该项目由科罗拉多州立大学管理。关于SGS-LTER项目的长期数据集及背景信息（提案、报告、照片等）均收录于科罗拉多州数字收藏馆的综合性项目收藏中（http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429）。数据表及其关联的元数据文档，采用生态元语言生成，可能通过服务于生态研究社区的其它数据存储库获取，并代表SGS-LTER项目收藏的一部分。自1971年至1975年，对短草草原社区通常不会遇到的超出其范围的土壤水分、氮素以及水分与氮素混合物进行了施用，植物密度样本采集直至1977年，随后在1982年重新开始采样，采样频率由每年一次改为每两年一次。1970年至1974年的初始采样结果显示，水分及水分与氮素处理对植物群落结构的影响最为显著，两种处理均增加了生物量，并在水分与氮素混合物处理中记录到了外来杂草物种。1982年至1991年的后续采样显示，与对照相比，水分与氮素混合物处理地块的外来杂草物种数量增加了十倍（Milchunas和Lauenroth，1995），这种由于植物组织与土壤有机质反馈机制导致的土壤氮素慢性升高，使得该地点的群落变化得以持续（Vinton和Burke，1995）。1998年，在历史研究站上叠加了六种新的处理方法：对照、糖、木质素、锯末、木质素与糖以及锯末与糖。2010年起，地块的采样频率将每五年进行一次。本研究的目标是考察植物群落随时间的变化，并探讨这些变化对监测潜在受压生态系统的意义。更多信息和参考材料可查阅：http://hdl.handle.net/10217/83317。本数据集包含的资源：资源标题：指向HTML文件的网站指针。文件名：网页，URL：https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-sgs&identifier=520 包含信息和数据文件下载链接的网页。