SGS-LTER Ecosystem Stress Area - long-term point-frame (percent basal cover) dataset following nutrient enrichment stress on the Central Plains Experimental Range in Nunn, Colorado, USA 1982-2011, 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=521 Webpage with information and links to data files for download

本数据集由科罗拉多州立大学管理的短草草原长期生态系统研究（SGS-LTER）项目的研究人员制作。关于SGS-LTER项目的长期数据集和背景信息（提案、报告、照片等）均包含在科罗拉多州数字收藏馆的综合项目收藏中（http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429）。数据表和相关元数据文档，采用生态元语言编制，可能通过服务生态研究社区的其它数据存储库获得，并代表SGS-LTER项目收藏的一部分。自1971年至1975年，对短草草原社区正常承受范围之外的水、氮以及水加氮水平进行了施用，植物密度样本收集直至1977年，随后在1982年重新开始采样，采样频率从每年一次变为每隔一年一次。1970年至1974年的初步采样表明，水和水加氮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，在水的加氮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，水加氮处理区域的外来杂草物种数量增加了十倍（Milchunas和Lauenroth，1995），这一群落变化由于植物组织/土壤有机质反馈机制导致的土壤氮水平持续升高而在该地点持续存在（Vinton和Burke，1995）。1998年，在历史研究站点上叠加了六种新的处理方法：对照、糖、木质素、锯末、木质素和糖以及锯末和糖。2010年起，将每五年对地块进行一次采样。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压力生态系统的意义。更多信息及参考文献材料可查阅：http://hdl.handle.net/10217/83317。本数据集中的资源包括：资源标题：指向HTML文件的网站指针。文件名：网页，网址：https://portal.edirepository.org/nis/mapbrowse?scope=knb-lter-sgs&identifier=521 包含信息和数据文件下载链接的网页。