SGS-LTER Graduate Student Research: Decomposition Rates as Biochemical Responses of US Great Plains Grasslands to Regional and Interannual Variability in Precipitation (1999-2001)

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. Additional information and referenced materials can be found: http://hdl.handle.net/10217/85531. Carbon (C) sequestration potential in grasslands is thought to be high due to the large soil organic carbon pools characteristic of these ecosystems. Inputs of C (aboveground net primary productivity) are highly correlated to precipitation across the Great Plains region; however, changes in C pool size at a specific site are governed by the relative input and output rates across time. Our objective was to quantify the ecosystem C response of three grassland community types (shortgrass steppe, mixed grass and tallgrass prairie) to interannual variation in precipitation. At five sites across a precipitation gradient in the Great Plains, we measured net primary production (NPP), soil respiration (SRESP), and litter decomposition rates for three consecutive years. NPP, SRESP, and litter decomposition increased from shortgrass steppe (175, 454, and 47 g C m-2 yr-1) to tallgrass prairie (408, 1221, and 348 g C m-2 yr-1 for NPP, SRESP, and litter decomposition respectively). Increased growing season precipitation between study years resulted in increased NPP, SRESP, and litter decomposition at almost all sites. However, the regional patterns of the interannual NPP, SRESP, and litter decomposition responses differ from each other. This data suggests NPP and SRESP are more sensitive to interannual changes in precipitation than litter decomposition, and that shortgrass steppe sites are more responsive to interannual variability in precipitation than mixed grass and tallgrass prairie.本数据包由参与短草草原长期生态研究（Shortgrass Steppe Long Term Ecological Research，缩写SGS-LTER）项目的研究者编制，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（含研究提案、报告、照片等）均收录于科罗拉多数字馆藏的综合项目馆藏中，访问链接为：http://digitool.library.colostate.edu/R/?func=collections&collection_id=3429。以生态元数据语言（Ecological Metadata Language）生成的数据表及关联元数据文档，亦可通过其他服务于生态研究社区的仓储平台获取，且属于更大范围的SGS-LTER项目馆藏的组成部分。更多相关信息及参考资料可访问：http://hdl.handle.net/10217/85531。草原生态系统因拥有规模庞大的土壤有机碳库，其碳固存潜力被学界广泛认为较高。北美大平原地区的碳输入（地上净初级生产力）与降水量呈高度相关关系；但特定站点的碳库规模变化，由跨时间尺度的碳输入与输出相对速率共同决定。本研究的目标是量化三种草原群落类型（短草草原、混合草原与高草草原）的生态系统碳响应，以应对降水量的年际波动。研究团队在北美大平原沿降水梯度设置的五个站点中，连续三年测量了净初级生产力（Net Primary Productivity，缩写NPP）、土壤呼吸（Soil Respiration，缩写SRESP）以及枯落物分解速率。研究结果显示，NPP、SRESP与枯落物分解速率从短草草原（分别为175、454和47 g C m⁻² yr⁻¹）逐步升高至高草草原（NPP、SRESP及枯落物分解速率分别为408、1221和348 g C m⁻² yr⁻¹）。研究年度间生长季降水量增加，导致几乎所有站点的NPP、SRESP与枯落物分解速率均出现提升。不过，年际间NPP、SRESP及枯落物分解的区域响应模式存在显著差异。本数据集表明，相较于枯落物分解，NPP与SRESP对降水量的年际变化更为敏感；且短草草原站点相较于混合草原与高草草原，对降水量的年际变异性响应更为显著。