The shortgrass steppe (SGS) LTER has been in operation since 1982. The key questions that guide our work are:

Our conceptual framework asserts that SGS ecological structure and function are governed by climate, natural disturbance, physiography, human use, and biotic interactions. SGS-LTER work is divided into three topic areas, 1) Population Dynamics (plants and heterotrophs), 2) Biogeochemical Dynamics, and 3) Land-Atmosphere Interactions. Disturbances are of such importance that they are embedded in each of our topic areas. In addition to continuing our long-term experiments that address our key questions, we are initiating new studies that primarily focus on Question 3. The discussion below focuses mostly on this new work.

Population Dynamics: Plant Dynamics and Ecosystem Interactions: One grass species, Bouteloua gracilis, contributes most to biomass and net primary production (NPP), and has been the focus of most of our past work. We will initiate long-term studies of Opuntia polyacantha (prickly-pear cactus) a species that makes up a small proportion of NPP; its spiny growth form affords protection to other species and therefore may have a large effect under cattle grazing. Even though the SGS has proven quite resistant to invasive plants, the introduction of species that can successfully invade the SGS is inevitable. We propose to study the potential for invasion by plants with different life history attributes, and to survey extensively for new invasions.

Faunal Dynamics: The dynamics of small mammals simultaneously reflect and affect both the structure and function of the SGS ecosystem. We will continue our long-term studies tracking small mammal populations, their resources, and predators. New research will emphasize the dynamics of the black-tailed prairie dog (Cynomys ludovicianus) and its effects on biological diversity and ecosystem function. Prairie dogs were abundant in the past, but have been severely affected by poisoning, shooting, habitat destruction, and, most significantly, by an introduced bacterium that causes plague (Yersinia pestis). The prairie dog is now a candidate for listing under the Endangered Species Act. We will examine prairie dog dynamics as affected by plague.

Biogeochemical Dynamics: We conceive of biogeochemical processes as an integrated function of biotic components and those processes responsible for carbon and nutrient fluxes: primary production, decomposition, weathering, mineralization, and trace gas flux. We will continue to study variations in biogeochemistry as a function of climatic controls, and will initiate new studies that evaluate geologic (textural) and topographic controls, and balancing the N budget.

Land-Atmosphere: The processes with which we are primarily concerned are water, energy, and gaseous fluxes that represent important interactions between the ecosystem and the atmosphere. One of the most important alterations that has occurred and continues to occur on the SGS LTER is land use change. We will evaluate the interactions of human land use, biotic responses, and atmospheric processes at scales from local to regional.

Synthesis: The SGS has a major investment in simulation analysis, and each of our topic areas has simulation components. We will continue to synthesize long-term data both within and across research areas. Our new synthesis volume will be published during this next funding cycle.

Other Activities: Data management supports our research and contributes to ecoinformatics. We will continue to build our interactions with federal land management agencies, NGO’s, and the interested public. Through the use of supplemental funding, the SGS-LTER will focus on K-12 and community outreach through student mentoring, curriculum development, teacher professional development, community partnerships, and education research.

11/22/2002

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To contact us, please email: Sallie Sprague  (Sallie.Sprague@colostate.edu)