image of the shortgrass steppe

SGS-LTER Research Approaches Over Time

The research objectives of the SGS-LTER project were to investigate what mechanisms regulate processes such as aboveground plant production and nutrient cycling in the shortgrass steppe. Research questions focused on how biotic and abiotic components of the ecosystem are related, and where and when ecological relationships are most vulnerable to perturbations.  Scientists studied variations in the structure and function of the ecosystem at different spatial and temporal scales (Figure 1) and sought to understand how these aspects are governed by climate, natural disturbance, biota, physiography, and human use (Figure 2).


Figure 1. Conceptual framework in use from 1996-2002 to illustrate relationships among the key factors that determine the structure and function of shortgrass steppe ecosystem.  At this time, the spatial scale of SGS-LTER investigations was that of the CPER (6,500 ha) and Pawnee National Grassland (78,100 ha).  The scales at which variations in processes were detected were illustrated over space as a layer and depicted over time as a graph. The stylized map layers represented the relative scale of spatial variability and the associated graph the relative temporal variability.  For example, the spatial variability of climatic variables was considered as relatively small while the temporal variability was pictured as highly dynamic.  By contrast, physiography was depicted as spatially variable at a fairly large scale (km2) but with very little temporal variability.

Figure 2. Conceptual framework used for coordinating SGS-LTER research areas from 2002-2010, illustrated an arrangement of how climate, natural disturbance, physiography, human use, and biotic interactions were studied as the major determinants of ecological structure and function of the shortgrass steppe.

Scientists at the SGS-LTER worked by integrating long-term monitoring data, designing and implementing manipulative experiments, advancing modeling techniques, and synthesizing data to develop innovative research, education, and outreach approaches.  From early on, they were tasked with disseminating information and providing data that would be helpful for managing sustainable rangelands, assessing impacts of global change, and developing GK-12 and university curricula.  Funding from NSF for the SGS-LTER project ended in 2014.  Over 45 years, the IBP and LTER scientists produced almost 1200 journal publications, almost 400 book chapters, over 200 theses, and more than 100 core, long-term datasets with open access.  Scientists continue to use the field research site and the rich legacy of SGS-LTER for new projects including the Summer Soil Institute, the Semi-Arid Grasslands Research Center and the USDA Long-Term AgroEcosystem Research Network.

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 Nicole Kaplan.