|Regionalization at the SGS|
The Shortgrass Steppe Long Term Ecological Research Project has been conducting regional analysis since 1988. Our overall goal in this research has been to understand the current pattern of ecosystem structure and function in the central grasslands of the U.S., and to assess the sensitivity of the region to changes in climate and landuse. This work has been supported in the past by additional funding from the National Science Foundation, and our LTER group and an extended set of scientists is currently supported by funding from the Environmental Protection Agency and the National Institutes of Health.
Our initial analyses, conducted in the late 1980's, focused on the analysis of regional point data, and assessed the relationships between climatic and soil variables and aboveground net primary productivity (Sala et al.. 1988) and soil carbon (Burke et al. 1989).
More recently, we have developed a large spatial database , organized in a geographic information system, of climatic variables ( precipitation and temperature ), soils data , plant species distributions, and landuse. Our three sets of questions have been:
We use two general techniques in this research (Burke et al. 1991). The first is pattern analysis, in which we conduct multivariate analysis on the data, to establish important relationships among variables. The second is simulation analysis, in which we link our spatial database to simulation models to extrapolate across the region and into the future (Coleman et al, 1994). A summary of our most recently completed work is listed in our 1996 progress report
To address the first question on plant species distributions, we have conducted spatial analyses of our regional maps of many climatic and soil factors, and a large spatial database of plant species distributions( C3 plant distribution and >C4 plant distribution ) and primary productivity ( C3 ANPP and C4 ANPP ) (Fan 1993, Epstein et al. in pressa, Epstein et al. in pressb, Epstein et al. in revision, Epstein et al. submitted). We have conducted numerous analysis using remotely sensed data and field data to further assess the relationships between plant productivity and plant functional type across the region (Paruelo 1995, Paruelo and Lauenroth 1995, Paruelo et al. 1995, Paruelo and Lauenroth in press, Paruelo and Tomasel in press, Paruelo et al. in press, Lauenroth et al. submitted, Paruelo et al. submitted, Paruelo and Lauenroth submitted). We have also linked the Steppe model (Coffin and Lauenroth 1990) with our database to predict the effects of global climate change on plant species distributions (Coffin and Lauenroth in press).
To address the second question, regarding the controls over landuse, we have conducted pattern analysis of the relationships among landuse ( Loveland Land Use Map USGS Landuse/Landcover Map ), climate and soils. We have conducted an initial pilot survey (Burke et al. 1994), and are currently completing our assessment for the region at large. This work is being expanded by our new NIH grant, which focuses on the social and economic controls of landuse management.
We have simulated the influence of historical landuse management on soil carbon stores and grain yield . Following a pilot study (Burke et al. 1994), we have conducted an analysis of the entire region; this work is currently in preparation for publication. We are linking ecosystem simulation models with regional atmospheric models (Pielke et al. 1992, Pielke et al. in press) to assess the influence of landuse on regional scale atmospheric dynamics. Our new EPA grant is supporting us to expand this work considerably, to include simulations of trace gas flux, regional climate, primary productivity, and total carbon storage.
Finally, we have utilized our regional, spatial database to address the question: what area does our site adequately represent? To what area can we logically extrapolate the results from our site-level investigations (Burke and Lauenroth 1990). Our results suggest that the climate, soils, and landuse of the Shortgrass Steppe LTER site represent approximately 23% of the shortgrass steppe. For further information please see the site definition in our 1996 NSF Proposal.
For more information on the regional analysis being conducted by the Shortgrass Steppe LTER, please contact Dr. Indy Burke (firstname.lastname@example.org).
Burke, I.C., T.G.F. Kittel, W.K. Lauenroth, P. Snook, and C.M. Yonker. 1991. Regional analysis of the Central Great Plains: Sensitivity to climate variation. BioScience. 41 (): 685-692
Burke, I.C. and W.K. Lauenroth. 1993. What do LTER results mean? Extrapolating from site to region and decade to century. Ecological Modeling 67:19-35.
Burke, I.C., W.K. Lauenroth, W.J. Parton, and C.V. Cole. 1994. Interactions of land use and ecosystem function: A case study in the central Great Plains. pp. 79-95. In Groffman, P.M. and G.E. Likens . Integrated regional models: interactions between humans and their environment. Chapman Hall, New York, NY.
Coffin, D.P. and W.K. Lauenroth. 1990. A gap dynamics simulation model of succession in the shortgrass steppe.Ecological Modeling. 49 (): 229-266
Coffin, D.P. and W.K. Lauenroth. 1996. Transient responses of North American grasslands to changes in climate. Journal of Climatic Change. in press.
Coleman, M.B., T.L. Bearly, I.C. Burke,and W.K. Lauenroth. 1994. Linking ecological simulation models to geographic information systems: an automated solution. pp. 397-412. In Michener, W. and J. Brunt . Environmental Information Management and Analysis: Ecosystem to Global Scales. Taylor and Francis, London..
Epstein, H.E., W.K. Lauenroth, I.C. Burke and D.P. Coffin. Regional productivity patterns of C3 and C4 functional types in the Great Plains of the U.S. Ecology (in press).
Epstein, H.E., W.K. Lauenroth, I.C. Burke and D.P. Coffin. Ecological responses of dominant grasses along two climatic gradients in the Great Plains of the U.S. Journal of Vegetation Science (in press).
Epstein, H.E., W.K. Lauenroth and I.C. Burke. Revealing the effects of temperature and soil texture on ANPP in the Great Plains of the U.S. Ecology (in revision).
Epstein, H.E., W.K. Lauenroth, I.C. Burke and D.P. Coffin. Regional productivity patterns of plant species in the Great Plains of the U.S. Vegetatio (submitted).
Fan, W. 1993. Regional analysis of plant species and environmental variables in eastern Colorado. PhD Dissertation, Colorado State University, Fort Collins, CO.
Lauenroth, W.K., H.E. Epstein, J.M. Paruelo, I.C. Burke, M.R. Aguiar, and O.E. Sala. 1996. Potential effects of climate change on the temperate zones of North and South America. In G.A. Bradshaw and D. Soto. Disruptions in North and South American landscapes: interactions between natural and human processes. Springer Verlag. submitted.
Pareulo, J.M. and W.K. Lauenroth. 1996. Interannual variability of NDVI and their relationship to climate for North American shrublands and grasslands. Remote Sensing of Environment. submitted.
Paruelo, J.M. and W.K. Lauenroth. 1995. Regional patterns of NDVI in North American shrublands and grasslands. Ecology. 76:1888-1898.
Paruelo, J.M., E.G. Jobbagy, O.E. Sala, W.K. Lauenroth, and I.C. Burke. 1996. Regional models in ecology: an evaluation of their predictive power. Ecological Applications. submitted.
Paruelo, J.M., and F. Tomasel. 1996. Prediction of functional characteristics of ecosystems: a comparison of artificial neural networks and regression models. Ecological Modelling. in press.
Paruelo, J.M., H.E. Epstein, W.K. Lauenroth, and I.C. Burke. 1996. ANPP Estimates from NDVI for the Central Grassland Region of the U.S. Ecology 78. in press.
Paruelo, J.M., W.K. Lauenroth, H.E. Epstein, I.C. Burke, M.R. Aguiar, and O.E. Sala. 1995. Regional climatic similarities in the temperate zones of North and South America. Journal of Biogeography. 22: 915-925.
Paruelo, J.M., W.K. Lauenroth. 1996. Climatic controls of the distribution of function types in grasslands and shrublands of North America. Ecological Applications 77. in press.
Paruelo, J.M. 1995. Regional patterns and climatic controls of the structure and function of North American grasslands and shrublands. PhD Dissertation, Colorado State University, Fort Collins.
Pielke, R.A., W.R. Cotton, R.L. Walko, C.J. Tremback, W.A. Lyons, L.D. Grasso, M.E. Nicholls, M.D. Moran, D.A. Wesley, T.J. Lee, and J.H. Copeland, 1992: A comprehensive meteorological modeling system -- RAMS. Meteor. Atmos. Phys., 49, 69-91.
Pielke, R.A., T.J. Lee, J.H. Copeland, J.L. Eastman, C.L. Ziegler, and C.A. Finley, 1996: Use of USGS-provided data to improve weather and climate simulations. Ecological Applications, (in press).
Sala, O.E., W.J. Parton, W.A. Joyce, and W.K. Lauenroth. 1988. Primary production of the central grassland region of the United States: spatial patterns and major controls. Ecology 69: 40- 45.