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
Development of a 2001 National Land Cover Database for the United States
Gross primary productivity of the true steppe in central Asia in relation to NDVI: scaling up CO2 fluxes
Intra-seasonal mapping of CO2 flux in rangelands of northern Kazakhstan at one-kilometer resolution
An approach for mapping large-area impervious surfaces: Synergistic use of Landsat-7 ETM+ and high spatial resolution imagery
Derivation of a tasselled cap transformation based on Landsat 7 at-satellite reflectance
Satellite mapping of surface biophysical parameters at the biome scale over the North American grasslands: A case study
Completion of the 1990s National Land Cover Data set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources
Sky type discrimination using a ground-based sun photometer
An analysis of relationships among climate forcing and time-integrated NDVI of grasslands over the U.S. northern and central Great Plains
NDVI, C3 and C4 production, and distributions in Great Plains grassland land cover classes
Grassland canopy parameters and their relationships to remotely sensed vegetation indices in the Nebraska Sand Hills
- 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: 47Development of a 2001 National Land Cover Database for the United States
Multi-Resolution Land Characterization 2001 (MRLC 2001) is a second-generation Federal consortium designed to create an updated pool of nation-wide Landsat 5 and 7 imagery and derive a second-generation National Land Cover Database (NLCD 2001). The objectives of this multi-layer, multi-source database are two fold: first, to provide consistent land cover for all 50 States, and second, to provide aAuthorsCollin G. Homer, Chengquan Huang, Limin Yang, Bruce K. Wylie, Michael CoanGross primary productivity of the true steppe in central Asia in relation to NDVI: scaling up CO2 fluxes
Compared to other characteristics of CO2 exchange, gross primary productivity (P g ) is most directly related to photosynthetic activity. Until recently, it was considered difficult to obtain measurement-based P g . The objective of our study was to evaluate if P g can be estimated from continuous CO2 flux measurements using nonlinear identification of the nonrectangular hyperbolic model of ecosysAuthorsTagir G. Gilmanov, Douglas A. Johnson, Nicanor Z. Saliendra, Kanat Akshalov, Bruce K. WylieIntra-seasonal mapping of CO2 flux in rangelands of northern Kazakhstan at one-kilometer resolution
Algorithms that establish relationships between variables obtained through remote sensing and geographic information system (GIS) technologies are needed to allow the scaling up of site-specific CO2 flux measurements to regional levels. We obtained Bowen ratio-energy balance (BREB) flux tower measurements during the growing seasons of 1998-2000 above a grassland steppe in Kazakhstan. These BREB daAuthorsB.K. Wylie, T.G. Gilmanov, D.A. Johnson, Nicanor Z. Saliendra, K. Akshalov, L.L. Tieszen, B. C. Reed, Emilio LacaAn approach for mapping large-area impervious surfaces: Synergistic use of Landsat-7 ETM+ and high spatial resolution imagery
A wide range of urban ecosystem studies, including urban hydrology, urban climate, land use planning, and resource management, require current and accurate geospatial data of urban impervious surfaces. We developed an approach to quantify urban impervious surfaces as a continuous variable by using multisensor and multisource datasets. Subpixel percent impervious surfaces at 30-m resolution were maAuthorsLimin Yang, Chengquan Huang, Collin G. Homer, Bruce K. Wylie, Michael CoanDerivation of a tasselled cap transformation based on Landsat 7 at-satellite reflectance
A new tasselled cap transformation based on Landsat 7 at-satellite reflectance was developed. This transformation is most appropriate for regional applications where atmospheric correction is not feasible. The brightness, greenness and wetness of the derived transformation collectively explained over 97% of the spectral variance of the individual scenes used in this study.AuthorsChengquan Huang, Bruce K. Wylie, Limin Yang, Collin G. Homer, G. ZylstraSatellite mapping of surface biophysical parameters at the biome scale over the North American grasslands: A case study
Quantification of biophysical parameters is needed by terrestrial process modeling and other applications. A study testing the role of multispectral data for monitoring biophysical parameters was conducted over a network of grassland field sites in the Great Plains of North America. Grassland biophysical parameters [leaf area index (LAI), fraction of absorbed photosynthetically active radiation (fAuthorsB.K. Wylie, D. J. Meyer, L.L. Tieszen, S. MannelCompletion of the 1990s National Land Cover Data set for the conterminous United States from Landsat Thematic Mapper data and ancillary data sources
No abstract available.AuthorsJames E. Vogelmann, Stephen M. Howard, Limin Yang, Charles R. Larson, Bruce K. Wylie, J. Nicholas Van DrielSky type discrimination using a ground-based sun photometer
A 2-year feasibility study was conducted at the USGS EROS Data Center, South Dakota (43.733°N, 96.6167°W) to assess whether a four-band, ground-based, sun photometer could be used to discriminate sky types. The results indicate that unique spectral signatures do exist between sunny skies (including clear and hazy skies) and cirrus, and cirrostratus, altocumulus or fair-weather cumulus, and thin stAuthorsThomas P. DeFelice, Bruce K. WylieAn analysis of relationships among climate forcing and time-integrated NDVI of grasslands over the U.S. northern and central Great Plains
Time-integrated normalized difference vegetation index (TI NDVI) derived from the multitemporal satellite imagery (1989–1993) was used as a surrogate for primary production to investigate climate impacts on grassland performance for central and northern Great Plains grasslands. Results suggest that spatial and temporal variability in growing season precipitation, potential evapotranspiration, andAuthorsLimin Yang, Bruce K. Wylie, Larry L. Tieszen, Bradley C. ReedNDVI, C3 and C4 production, and distributions in Great Plains grassland land cover classes
The distributions of C3 and C4 grasses were used to interpret the distribution, seasonal performance, and potential production of grasslands in the Great Plains of North America. Thirteen major grassland seasonal land cover classes were studied with data from three distinct sources. Normalized Difference Vegetation Index (NDVI) data derived from the National Oceanic and Atmospheric AdministrationAuthorsL.L. Tieszen, Bradley C. Reed, Norman B. Bliss, Bruce K. Wylie, Benjamin D. DeJongGrassland canopy parameters and their relationships to remotely sensed vegetation indices in the Nebraska Sand Hills
Relationships among spectral vegetation indices and grassland biophysical parameters including the effects of varying levels of standing dead vegetation, range sites, and range plant communities were examined. Range plant communities consisting of northern mixed grass prairie and a smooth brome field as well as range sites and management in a Sand Hills bluestem prairie were sampled with a groundAuthorsBruce K. Wylie, Donovan D. DeJong, Larry L. Tieszen, Mario E. Biondini