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4 - Five Decades of Modeling Supporting the Systems Ecology Paradigm
- Edited by Robert G. Woodmansee, Colorado State University, John C. Moore, Colorado State University, Dennis S. Ojima, Colorado State University, Laurie Richards, Colorado State University
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- Book:
- Natural Resource Management Reimagined
- Published online:
- 25 February 2021
- Print publication:
- 11 March 2021, pp 90-130
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Summary
Ecosystem modeling, a pillar of the systems ecology paradigm (SEP), addresses questions such as, how much carbon and nitrogen are cycled within ecological sites, landscapes, or indeed the earth system? Or how are human activities modifying these flows? Modeling, when coupled with field and laboratory studies, represents the essence of the SEP in that they embody accumulated knowledge and generate hypotheses to test understanding of ecosystem processes and behavior. Initially, ecosystem models were primarily used to improve our understanding about how biophysical aspects of ecosystems operate. However, current ecosystem models are widely used to make accurate predictions about how large-scale phenomena such as climate change and management practices impact ecosystem dynamics and assess potential effects of these changes on economic activity and policy making. In sum, ecosystem models embedded in the SEP remain our best mechanism to integrate diverse types of knowledge regarding how the earth system functions and to make quantitative predictions that can be confronted with observations of reality. Modeling efforts discussed are the Century ecosystem model, DayCent ecosystem model, Grassland Ecosystem Model ELM, food web models, Savanna model, agent-based and coupled systems modeling, and Bayesian modeling.
11 - Simulated Biogeochemical Impacts of Historical Land-Use Changes in the U.S. Great Plains from 1870 to 2003
- Edited by Daniel G. Brown, University of Michigan, Ann Arbor, Derek T. Robinson, University of Waterloo, Ontario, Nancy H. F. French, Michigan Technological University, Bradley C. Reed, United States Geological Survey, California
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- Book:
- Land Use and the Carbon Cycle
- Published online:
- 05 February 2013
- Print publication:
- 28 January 2013, pp 287-304
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Summary
Introduction
Extensive research has shown that agricultural land-use practices have substantial impacts on the environment, including (1) release of 50 percent of soil carbon (C) following cultivation of the soil, (2) enhanced soil nitrous oxide (N2O) emissions, (3) reduced soil fertility, (4) increases in nitrate (NO3−) leaching into groundwater and streams, (5) changes in plant production, and (6) changes in energy balance and water fluxes (Pielke et al. 2007). By linking observed detailed land-use data for the U.S. Great Plains over the past 150 years to the DayCent ecosystem model (Parton et al. 1998), this review demonstrates how historical changes in land use have affected soil organic carbon (SOC), soil fertility, plant production, and greenhouse gas (GHG) fluxes. A detailed description of the procedure used to link the observed U.S. Great Plains land-use data with the DayCent model, along with a comparison of observed and DayCent simulated historical changes in crop yields for the major crops (corn, wheat, sorghum, hay, and cotton) is presented by Hartman et al. (2011).
The Great Plains region of the United States is unique because by the time it was settled by Euro-American farmers, many modern institutions for information gathering and data analysis were already in place. The settlement and subsequent ecological transformation of this region is therefore well documented in the U.S. censuses of population and agriculture, which contain detailed data at the county level regarding changes in land use, animal production, yields for crops grown under both dryland and irrigated conditions, economic value of animal and crop raising, and movements of human populations, first on the decadal scale and then every five years for agriculture beginning in 1925. These data have been digitized for the Great Plains and are now publicly available in machine-readable form (Gutmann 2005a, 2005b).