Carbon Flux Quantification in the Great Plains Active
Gross primary production (GPP) and ecosystem respiration (Re) are the fundamental environmental characteristics which drive carbon exchanges between terrestrial ecosystems and the atmosphere (Chapin and others, 2009), although other exchanges of carbon, for example, export or direct oxidation (Lovett and others, 2006) can modify net ecosystem production (NEP).
The long-term accumulation of carbon in terrestrial ecosystems results in systems in which carbon contents of soil organic matter (SOM) often exceeds that of biomass (Post and Kwon, 2000). This SOM pool exists as a steady state between GPP and Re in ecosystems unless drivers change or perturbations (for example, climate) occur. As illustrated by Wilhelm and others (2010), conversion of grasslands to agriculture and cultivation practices can result in reduced soil carbon with the release of CO2 to the air by stimulated oxidation, contributing to higher Re. Specific land-use and management practices, therefore, influences NEP with additional reactions caused by irregular climate conditions (Luo, 2007). The isotopic status of the SOM reflects the net inputs by C3 and C4 systems and therefore in native prairies documents climate change (von Fischer and others, 2008) through the Holocene.
The recent concerns and questions being raised over issues such as climate change and alternative energy have driven significant changes in land management practices, especially in the highly agricultural Midwestern U.S. (Wilhelm, and others, 2010). It is important to insure the sustainability of these and other land management practices and to be aware of the potential impacts that such practices can have on NEP or exchanges of carbon with the atmosphere (Anderson-Teixeira and others, 2009). Since the mid-1990s, a highly advanced and growing network of micrometeorological towers has been utilizing eddy covariance methods to measure the exchanges of carbon dioxide, water vapor, and energy between terrestrial ecosystems and the atmosphere. These towers, also known as flux towers, are being strategically placed throughout North America in an effort to effectively represent major ecosystems and to make these data available to the scientific community. Such a dataset offers a unique and valuable resource for use in the study and quantification of carbon exchanges between terrestrial ecosystems and the atmosphere and can ultimately lead to answering the questions raised about resource sustainability.
The focus of this study has been defined as the North American Great Plains, a region primarily consisting of grassland and cultivated cropland (Figure 1). Currently, more than 100 site-years of flux-tower measurements, represented by over 30 individual cropland or grassland sites throughout the Great Plains, have been accumulated and are being analyzed in conjunction with applicable remotely sensed data. Given the terrestrial composition of the focus area, it is essential to account for both grassland and cultivated cropland ecosystems to achieve a comprehensive quantification of NEP. Recent studies have shown that, through the use of complex regression tree modeling, flux tower measurements and remotely sensed data can be utilized to quantify and map NEP in grassland ecosystems across the Great Plains (Zhang and others, 2011) and the dramatic affect that annual climate and land use has on NEP.
Applying similar quantification methods to the cropland ecosystems of the Great Plains will allow for further expansion of NEP quantification and mapping of the region. Such an application first required that major crop types commonly grown in the Great Plains, such as corn, soybeans, and wheat were known with relatively high spatial and temporal resolution. We developed and implemented a crop type classification model, based primarily on weekly time series normalized differential vegetation index (NDVI) data, to account for these major crop types. The models were originally developed for the Greater Platte River Basin, but have the capability to be expanded to cover larger regions, such as the Great Plains. Our efforts are progressing in the area of cropland NEP quantification in the Great Plains and still require additional acquisition and processing of source flux tower data and the development of carbon flux algorithms for the major crop types in the region. Attaining these lingering aspects of carbon fluxes in the Great Plains will greatly increase our ability to comprehensively quantify NEP in the region.
Through all of our research and development in this area, we have also devised an approach that effectively identifies and maps areas within the Great Plains which are poorly represented by the current flux tower distribution. This information could be utilized for future management and planning purposes of the flux tower network.
We integrate our flux quantification with detailed documentation of the carbon isotope status of soil organic matter (SOM) throughout the soil profile and in various particle size fractions. This allows us to quantify C3 and C4 contributions to the SOM, and our analyses across the latitudes of native prairies in North America allow a reconstruction of past systems from which climate information is derived.
Below are publications associated with this project.
Rapid crop cover mapping for the conterminous United States
Annual crop type classification of the U.S. Great Plains for 2000 to 2011
Detecting the influence of best management practices on vegetation near ephemeral streams with Landsat data
Productivity and carbon dioxide exchange of leguminous crops: estimates from flux tower measurements
Influence of management and precipitation on carbon fluxes in greatplains grasslands
Detecting channel riparian vegetation response to best-management-practices implementation in ephemeral streams with the use of spot high-resolution visible imagery
Net ecosystem productivity of temperate grasslands in northern China: An upscaling study
Optimal placement of off-stream water sources for ephemeral stream recovery
Linking phenology and biomass productivity in South Dakota mixed-grass prairie
Monitoring the status of forests and rangelands in the Western United States using ecosystem performance anomalies
CO2 uptake and ecophysiological parameters of the grain crops of midcontinent North America: estimates from flux tower measurements
Ecosystem performance monitoring of rangelands by integrating modeling and remote sensing
Crop classification modelling using remote sensing and environmental data in the Greater Platte River Basin, USA
- Overview
Gross primary production (GPP) and ecosystem respiration (Re) are the fundamental environmental characteristics which drive carbon exchanges between terrestrial ecosystems and the atmosphere (Chapin and others, 2009), although other exchanges of carbon, for example, export or direct oxidation (Lovett and others, 2006) can modify net ecosystem production (NEP).
The long-term accumulation of carbon in terrestrial ecosystems results in systems in which carbon contents of soil organic matter (SOM) often exceeds that of biomass (Post and Kwon, 2000). This SOM pool exists as a steady state between GPP and Re in ecosystems unless drivers change or perturbations (for example, climate) occur. As illustrated by Wilhelm and others (2010), conversion of grasslands to agriculture and cultivation practices can result in reduced soil carbon with the release of CO2 to the air by stimulated oxidation, contributing to higher Re. Specific land-use and management practices, therefore, influences NEP with additional reactions caused by irregular climate conditions (Luo, 2007). The isotopic status of the SOM reflects the net inputs by C3 and C4 systems and therefore in native prairies documents climate change (von Fischer and others, 2008) through the Holocene.
The recent concerns and questions being raised over issues such as climate change and alternative energy have driven significant changes in land management practices, especially in the highly agricultural Midwestern U.S. (Wilhelm, and others, 2010). It is important to insure the sustainability of these and other land management practices and to be aware of the potential impacts that such practices can have on NEP or exchanges of carbon with the atmosphere (Anderson-Teixeira and others, 2009). Since the mid-1990s, a highly advanced and growing network of micrometeorological towers has been utilizing eddy covariance methods to measure the exchanges of carbon dioxide, water vapor, and energy between terrestrial ecosystems and the atmosphere. These towers, also known as flux towers, are being strategically placed throughout North America in an effort to effectively represent major ecosystems and to make these data available to the scientific community. Such a dataset offers a unique and valuable resource for use in the study and quantification of carbon exchanges between terrestrial ecosystems and the atmosphere and can ultimately lead to answering the questions raised about resource sustainability.
The focus of this study has been defined as the North American Great Plains, a region primarily consisting of grassland and cultivated cropland (Figure 1). Currently, more than 100 site-years of flux-tower measurements, represented by over 30 individual cropland or grassland sites throughout the Great Plains, have been accumulated and are being analyzed in conjunction with applicable remotely sensed data. Given the terrestrial composition of the focus area, it is essential to account for both grassland and cultivated cropland ecosystems to achieve a comprehensive quantification of NEP. Recent studies have shown that, through the use of complex regression tree modeling, flux tower measurements and remotely sensed data can be utilized to quantify and map NEP in grassland ecosystems across the Great Plains (Zhang and others, 2011) and the dramatic affect that annual climate and land use has on NEP.
Applying similar quantification methods to the cropland ecosystems of the Great Plains will allow for further expansion of NEP quantification and mapping of the region. Such an application first required that major crop types commonly grown in the Great Plains, such as corn, soybeans, and wheat were known with relatively high spatial and temporal resolution. We developed and implemented a crop type classification model, based primarily on weekly time series normalized differential vegetation index (NDVI) data, to account for these major crop types. The models were originally developed for the Greater Platte River Basin, but have the capability to be expanded to cover larger regions, such as the Great Plains. Our efforts are progressing in the area of cropland NEP quantification in the Great Plains and still require additional acquisition and processing of source flux tower data and the development of carbon flux algorithms for the major crop types in the region. Attaining these lingering aspects of carbon fluxes in the Great Plains will greatly increase our ability to comprehensively quantify NEP in the region.
Through all of our research and development in this area, we have also devised an approach that effectively identifies and maps areas within the Great Plains which are poorly represented by the current flux tower distribution. This information could be utilized for future management and planning purposes of the flux tower network.
We integrate our flux quantification with detailed documentation of the carbon isotope status of soil organic matter (SOM) throughout the soil profile and in various particle size fractions. This allows us to quantify C3 and C4 contributions to the SOM, and our analyses across the latitudes of native prairies in North America allow a reconstruction of past systems from which climate information is derived. - Publications
Below are publications associated with this project.
Rapid crop cover mapping for the conterminous United States
Timely crop cover maps with sufficient resolution are important components to various environmental planning and research applications. Through the modification and use of a previously developed crop classification model (CCM), which was originally developed to generate historical annual crop cover maps, we hypothesized that such crop cover maps could be generated rapidly during the growing seasonAuthorsDevendra Dahal, Bruce K. Wylie, Daniel HowardFilter Total Items: 47Annual crop type classification of the U.S. Great Plains for 2000 to 2011
The purpose of this study was to increase the spatial and temporal availability of crop classification data. In this study, nearly 16.2 million crop observation points were used in the training of the US Great Plains classification tree crop type model (CTM). Each observation point was further defined by weekly Normalized Difference Vegetation Index, annual climate, and a number of other biogeophyAuthorsDaniel M. Howard, Bruce K. WylieDetecting the influence of best management practices on vegetation near ephemeral streams with Landsat data
Various best management practices (BMPs) have been implemented on rangelands with the goals of controlling nonpoint source pollution, reducing the impact of livestock in ecologically important riparian areas, and improving grazing distribution. Providing off-stream water sources to livestock in pastures, cross-fencing, and rotational grazing are common rangeland BMPs that have demonstrated successAuthorsMatthew B. Rigge, Alexander Smart, Bruce K. Wylie, Kendall de Van KampProductivity and carbon dioxide exchange of leguminous crops: estimates from flux tower measurements
Net CO2 exchange data of legume crops at 17 flux tower sites in North America and three sites in Europe representing 29 site-years of measurements were partitioned into gross photosynthesis and ecosystem respiration by using the nonrectangular hyperbolic light-response function method. The analyses produced net CO2 exchange data and new ecosystem-scale ecophysiological parameter estimates for leguAuthorsTagir G. Gilmanov, John M. Baker, Carl J. Bernacchi, David P. Billesbach, George G. Burba, Saulo Castro, Jiquan Chen, Werner Eugster, Marc L. Fischer, John A. Gamon, Maheteme T. Gebremedhin, Aaron J. Glenn, Timothy J. Griffis, Jerry L. Hatfield, Mark W. Heuer, Daniel M. Howard, Monique Y. Leclerc, Henry W. Loescher, Oliver Marloie, Tilden P. Meyers, Albert Olioso, Rebecca L. Phillips, John H. Prueger, R. Howard Skinner, Andrew E. Suyker, Mario Tenuta, Bruce K. WylieInfluence of management and precipitation on carbon fluxes in greatplains grasslands
Suitable management and sufficient precipitation on grasslands can provide carbon sinks. The net carbon accumulation of a site from the atmosphere, modeled as the Net Ecosystem Productivity (NEP), is a useful means to gauge carbon balance. Previous research has developed methods to integrate flux tower data with satellite biophysical datasets to estimate NEP across large regions. A related methodAuthorsMatthew B. Rigge, Bruce K. Wylie, Li Zhang, Stephen P. BoyteDetecting channel riparian vegetation response to best-management-practices implementation in ephemeral streams with the use of spot high-resolution visible imagery
Heavily grazed riparian areas are commonly subject to channel incision, a lower water table, and reduced vegetation, resulting in sediment delivery above normal regimes. Riparian and in-channel vegetation functions as a roughness element and dissipates flow energy, maintaining stable channel geometry. Ash Creek, a tributary of the Bad River in western South Dakota contains a high proportion of incAuthorsKendall Vande Kamp, Matthew B. Rigge, Nels H. Troelstrup, Alexander J. Smart, Bruce WylieNet ecosystem productivity of temperate grasslands in northern China: An upscaling study
Grassland is one of the widespread biome types globally, and plays an important role in the terrestrial carbon cycle. We examined net ecosystem production (NEP) for the temperate grasslands in northern China from 2000 to 2010. We combined flux observations, satellite data, and climate data to develop a piecewise regression model for NEP, and then used the model to map NEP for grasslands in northerAuthorsLi Zhang, Huadong Guo, Gensuo Jia, Bruce Wylie, Tagir Gilmanov, Daniel M. Howard, Lei Ji, Jingfeng Xiao, Jing Li, Wenping Yuan, Tianbao Zhao, Shiping Chen, Guangsheng Zhou, Tomomichi KatoOptimal placement of off-stream water sources for ephemeral stream recovery
Uneven and/or inefficient livestock distribution is often a product of an inadequate number and distribution of watering points. Placement of off-stream water practices (OSWP) in pastures is a key consideration in rangeland management plans and is critical to achieving riparian recovery by improving grazing evenness, while improving livestock performance. Effective OSWP placement also minimizes thAuthorsMatthew B. Rigge, Alexander Smart, Bruce WylieLinking phenology and biomass productivity in South Dakota mixed-grass prairie
Assessing the health of rangeland ecosystems based solely on annual biomass production does not fully describe plant community condition; the phenology of production can provide inferences on species composition, successional stage, and grazing impacts. We evaluate the productivity and phenology of western South Dakota mixed-grass prairie using 2000 to 2008 Moderate Resolution Imaging SpectrometerAuthorsMatthew Rigge, Alexander Smart, Bruce Wylie, Tagir Gilmanov, Patricia JohnsonMonitoring the status of forests and rangelands in the Western United States using ecosystem performance anomalies
The effects of land management and disturbance on ecosystem performance (i.e. biomass production) are often confounded by those of weather and site potential. The current study overcomes this issue by calculating the difference between actual and expected ecosystem performance (EEP) to generate ecosystem performance anomalies (EPA). This study aims to delineate and quantify average EPA from 2000–2AuthorsMatthew B. Rigge, Bruce Wylie, Yingxin Gu, Jayne Belnap, Khem P. Phuyal, Larry TieszenCO2 uptake and ecophysiological parameters of the grain crops of midcontinent North America: estimates from flux tower measurements
We analyzed net CO2 exchange data from 13 flux tower sites with 27 site-years of measurements over maize and wheat fields across midcontinent North America. A numerically robust “light-soil temperature-VPD”-based method was used to partition the data into photosynthetic assimilation and ecosystem respiration components. Year-round ecosystem-scale ecophysiological parameters of apparent quantum yieAuthorsTagir Gilmanov, Bruce Wylie, Larry Tieszen, Tilden P. Meyers, Vern S. Baron, Carl J. Bernacchi, David P. Billesbach, George G. Burba, Marc L. Fischer, Aaron J. Glenn, Niall P. Hanan, Jerry L. Hatfield, Mark W. Heuer, Steven E. Hollinger, Daniel M. Howard, Roser Matamala, John H. Prueger, Mario Tenuta, David G. YoungEcosystem performance monitoring of rangelands by integrating modeling and remote sensing
Monitoring rangeland ecosystem dynamics, production, and performance is valuable for researchers and land managers. However, ecosystem monitoring studies can be difficult to interpret and apply appropriately if management decisions and disturbances are inseparable from the ecosystem's climate signal. This study separates seasonal weather influences from influences caused by disturbances and manageAuthorsBruce K. Wylie, Stephen P. Boyte, Donald J. MajorCrop classification modelling using remote sensing and environmental data in the Greater Platte River Basin, USA
With an ever expanding population, potential climate variability and an increasing demand for agriculture-based alternative fuels, accurate agricultural land-cover classification for specific crops and their spatial distributions are becoming critical to researchers, policymakers, land managers and farmers. It is important to ensure the sustainability of these and other land uses and to quantify tAuthorsDaniel M. Howard, Bruce K. Wylie, Larry L. Tieszen