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.

本数据包由开展短草草原长期生态研究（Shortgrass Steppe Long Term Ecological Research, SGS-LTER）项目的研究人员编制，该项目由科罗拉多州立大学负责管理。SGS-LTER项目的长期数据集及背景资料（包括项目申请书、研究报告、影像资料等）均收录于科罗拉多数字馆藏（Digital Collections of Colorado）的综合项目馆藏中，访问链接为http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429。本数据集附带的数据表与采用生态元数据语言（Ecological Metadata Language）编写的元数据文档，亦可通过服务于生态研究社区的其他仓储获取，属于SGS-LTER大型项目馆藏的组成部分。1971年至1975年间，研究人员向样地施加了超出短草草原群落自然耐受范围的水分、氮肥及水氮复合处理。1971年至1977年期间持续开展植物密度监测，1982年恢复监测工作，并将采样频率从每年1次调整为每2年1次。1970年至1974年的首轮监测结果显示，水分处理与水氮复合处理对植物群落结构的影响最为显著：两类处理均提升了群落生物量，且水氮复合处理样地出现了外来杂草物种。1982年至1991年的后续监测表明，相较于对照组，水氮复合处理样地的外来杂草物种数量增长了10倍（Milchunas与Lauenroth, 1995）。由于植物组织与土壤有机质间的反馈机制引发土壤氮素长期富集，该样地的群落结构变化得以持续维持（Vinton与Burke, 1995）。1998年，研究人员在该历史样地上新增了6组处理，具体为：对照组、蔗糖组、木质素组、锯末组、木质素+蔗糖组以及锯末+蔗糖组。2010年起，样地将每5年采样一次。本研究旨在探究植物群落随时间的演变规律，并探讨此类变化对潜在受胁迫生态系统监测工作的启示。更多相关信息及参考资料可通过以下链接获取：http://hdl.handle.net/10217/83317。