SGS-LTER Graduate Student Research: Belowground Net Primary Production 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, SGS-LTER）项目的科研人员编制，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（包含研究方案、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。
本数据表及配套的元数据文档采用生态元数据语言（Ecological Metadata Language）编写，可通过服务于生态研究社群的其他仓储获取，属于SGS-LTER综合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典型的庞大土壤有机碳库，其碳固存潜力被认为较高。大平原地区的碳输入（即地上净初级生产力）与降水量高度相关，但特定站点的碳库规模变化，受时间维度上相对的碳输入与输出速率共同调控。本研究的目标是量化三种草原群落类型（短草草原、混合草原及高草草原）的生态系统碳响应，以应对降水量的年际变化。

研究团队在大平原沿降水梯度设置的五个站点中，连续三年测定了净初级生产力（Net Primary Production, NPP）、土壤呼吸（Soil Respiration, SRESP）以及枯落物分解速率。结果显示，从短草草原（三项指标分别为175、454、47 g C m⁻² yr⁻¹）到高草草原（净初级生产力、土壤呼吸及枯落物分解速率分别为408、1221、348 g C m⁻² yr⁻¹），上述三项指标均呈递增趋势。

研究年度内生长季降水量的增加，使得几乎所有站点的净初级生产力、土壤呼吸及枯落物分解速率均有所提升。但三者的年际响应区域模式存在差异。本研究数据表明，净初级生产力与土壤呼吸对降水量年际变化的敏感性高于枯落物分解，且短草草原站点相较于混合草原与高草草原站点，对降水量年际波动的响应更为显著。