Repository logo

Presentations

Permanent URI for this collection

https://hdl.handle.net/10217/195555

Browse

Browsing Presentations by Author "Burke, I. C., author"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Ecosystem carbon & nitrogen cycling across a precipitation gradient of the central Great Plains
    (Colorado State University. Libraries, 2005) Knapp, A. K., author; Lauenroth, W. K., author; Burke, I. C., author; McCulley, R. L., author; SGS-LTER, Colorado State University, publisher
    Regional analyses have shown that ecosystem pools of carbon (C) and nitrogen (N) increase as precipitation increases from the semi-arid shortgrass steppe to the tallgrass prairie of the Central Great Plains. Models based on our functional understanding of biogeochemical processes predict that ecosystem C and N fluxes also increase across this community gradient; however, few field flux data exist to evaluate these predictions. We measured decomposition rates, soil respiration, and in situ net nitrogen mineralization at five sites across a precipitation gradient in the Great Plains region. Soil respiration (SResp) and the decomposition constant, k, for common substrate litter bags were significantly higher in the sub-humid mixed and tallgrass prairie (growing season average mid-day SResp = 7.20 μmol CO2 m-2 sec-1, k = 0.66 yr-1) than the semi-arid shortgrass steppe (SResp = 4.55 μmol CO2 m-2 sec-1, k = 0.32 yr-1). In contrast, in situ net nitrogen mineralization was not significantly different across sites. The C flux data concur with predictions from current biogeochemical models; however, the in situ net nitrogen mineralization results do not. We hypothesize that this discrepancy results from the difficulties associated with measuring in situ net nitrogen mineralization in soils with vastly different immobilization potentials.
  • Thumbnail Image
    ItemOpen Access
    Shortgrass Steppe Long Term Ecological Research
    (Colorado State University. Libraries, 2005) Moore, J. C., author; Lauenroth, W. K., author; Stapp, P. A., author; Burke, I. C., author; Kelly, E. F., author; Antolin, M. F., author; Pielke, R. A., author; Paustian, K. H., author; Parton, W. J., author; Mosier, A. R., author; Milchunas, D. G., author; Detling, J. K., author; Morgan, J. A., author; SGS-LTER, Colorado State University, publisher
    The shortgrass steppe (SGS) Long Term Ecological Research (LTER) site is part of a network of long-term research sites supported by the National Science Foundation. The network consists of 26 sites representing diverse ecosystems and research emphases, yet maintaining a common mission and sharing expertise and data. We assert that the ecological structure and function of the shortgrass steppe is governed by climate, human use, natural disturbance, biota and physiography. Our conceptual framework, right, depicts the relationship between these factors and our core research areas. Poster presented at the 7th Shortgrass Steppe Symposium held in Fort Collins, Colorado on 1/14/05.