SGS-LTER Effects of grazing on ecosystem structure and function (GZTX): Vegetation basal cover on the Central Plains Experimental Range, Nunn, Colorado, USA 1992-2011, ARS Study Number 32

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. When the CPER was established in 1939, researchers constructed a .5-1 ha grazing exclosure in each of the pastures. These areas have remained protected from grazing for the past 70 years. The remaining areas have been grazed for the past 20+ years. This collection of pastures and exclosures provided an extraordinary opportunity to reinitiate grazing and protection, and evaluate the balance between degradation and aggradation. We proposed to rearrange fences and expose areas to grazing that have been protected for 50 years, and protect areas from grazing that had been grazed for 50 years. The combinations of grazing conditions were: 1. Long-term protection 2. Long-term grazing (moderate) 3. 50 years of protection followed by grazing 4. 50 years of grazing followed by protection Net primary production, nitrogen dynamics, cattle utilization, and community dynamics of vegetation were measured. Additional information and referenced materials can be found: http://hdl.handle.net/10217/85596.本数据包由参与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（包括研究方案、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。本数据集的数据表及采用生态元数据语言（Ecological Metadata Language）生成的配套元数据文档，亦可通过其他服务于生态研究共同体的仓储平台获取，且均为SGS-LTER综合项目馆藏的组成部分。1939年CPER设立之初，研究人员在每个牧场均设置了一处0.5至1公顷的放牧排除区（grazing exclosure）。该类区域在过去70年间始终免受放牧干扰，其余牧场区域则已持续放牧20余年。这套牧场与放牧排除区的组合布局，为重新调整放牧与保护措施、评估生态退化与恢复的平衡关系提供了绝佳研究契机。本研究计划重新布设围栏：将已受50年保护的区域开放放牧，同时将已放牧50年的区域纳入永久保护范围。本次实验设置了4种放牧条件组合：1. 长期保护；2. 长期适度放牧；3. 50年保护后转为放牧；4. 50年放牧后转为保护。研究团队对净初级生产力、氮素动态、家畜采食率及植被群落动态开展了系统性测定。更多相关信息及参考资料可通过以下链接获取：http://hdl.handle.net/10217/85596。