SGS-LTER Ecosystem Stress Area - long-term density dataset following nutrient enrichment stress on the Central Plains Experimental Range in Nunn, Colorado, USA 1975-2011, ARS Study Number 3 (Reformatted to a Darwin Core Archive)

This data package is formatted as a Darwin Core Archive (DwC-A,
event core). For more information on Darwin Core see
https://www.tdwg.org/standards/dwc/. This Level 2 data package was
derived from the Level 1 data package found here: https://pasta.lternet.edu/package/metadata/eml/edi/330/3,
which was derived from the Level 0 data package found here:
https://pasta.lternet.edu/package/metadata/eml/knb-lter-sgs/520/8. The abstract below was extracted from the Level 0
data package and is included for context: 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. The Shortgrass Steppe Long Term Ecological Research (SGS-LTER) project was funded by
National Science Foundation as one of the first sites in the US LTER Network in 1982.
This collaborative, interdisciplinary research project was established in the Natural
Resource Ecology Lab at Colorado State University by ecosystem scientists who learned
novel approaches to study grassland ecosystems during the International Biome Program
(IBP) (1968-1974). The SGS-LTER project was built upon the foundation of data and
information obtained during IBP, as scientists sought to identify and follow, and often
manipulate in experiments, important ecosystem processes over the long-term. The
objectives of the SGS-LTER project were to investigate what mechanisms regulate
processes in the shortgrass steppe. Research questions focused on how biotic and abiotic
components of the ecosystem are coupled, where and when ecosystem components are most
vulnerable to perturbations, disseminating information that would be helpful for
rangeland management and assessing impacts of climate change. Scientists explored
variations in the structure and function of the ecosystem over space and time and sought
to understand how these aspects are governed by climate, natural disturbance, biota,
physiography, and human use. Scientists at the SGS-LTER integrated long-term monitoring
data, designed experimental studies, performed and advanced modeling techniques, and
synthesized data to conduct innovative research, education, and outreach. The core
SGS-LTER research site was established on the Central Plains Experimental Range (CPER)
in Nunn, Colorado, part of the United States Department of Agriculture’s Agricultural
Research Service. The research site sits in the rain shadow of the Rocky Mountains at
the western edge of the shortgrass steppe of North America. The shortgrass steppe
ecosystem evolved with grazing by the American bison, which has now been replaced by
cattle. Grazing by domestic livestock is the primary land use of native grassland, which
occupies about 60% of the land area of the shortgrass steppe. Short grasses dominate the
vegetation community, which have adapted to grazing and less than 400 mm of annual
rainfall. The topography is characterized by gently rolling hills, broad ephemeral
stream courses and low flat-topped terraces. Aspects of physiography regulate the
shortgrass steppe ecosystem, including landscape position, soil age, water holding
capacity, soil depth and surface texture which, in turn, determine such properties as
soil moisture storage, net primary productivity and the distribution of small mammals
such as prairie dogs and pocket gophers. SGS-LTER scientists have expanded their
research studies beyond the CPER to identify similar or different patterns in ecosystem
structure and function in North American grasslands; across the Great Plains region and
along the latitudinal gradient from Wyoming to Mexico. They also conducted cross-site
collaborative research and compared their results and tested theories in grasslands
located in South America, Asia and Africa. Funding from NSF for the SGS-LTER project
ends in 2014, but over thirty years of research has resulted in a scientific team with
diverse expertise, which produced over 1200 journal publications, almost 400 book
chapters and over 200 theses. Data, products and other information produced from the
SGS-LTER are available through the LTER Network Information System, Digital Collections
of Colorado at CSU or upon request through [e-mail].