Estimating crop net primary production using national inventory data and MODIS-derived parameters

Varaprasad Bandaru, Tristram O. West, Daniel M. Ricciuto, R. César Izaurralde

Research output: Contribution to journalArticlepeer-review

43 Scopus citations

Abstract

National estimates of spatially-resolved cropland net primary production (NPP) are needed for diagnostic and prognostic modeling of carbon sources, sinks, and net carbon flux between land and atmosphere. Cropland NPP estimates that correspond with existing cropland cover maps are needed to drive biogeochemical models at the local scale as well as national and continental scales. Existing satellite-based NPP products tend to underestimate NPP on croplands. An Agricultural Inventory-based Light Use Efficiency (AgI-LUE) framework was developed to estimate individual crop biophysical parameters for use in estimating crop-specific NPP over large multi-state regions. The method is documented here and evaluated for corn (Zea mays L.) and soybean (Glycine max L. Merr.) in Iowa and Illinois in 2006 and 2007. The method includes a crop-specific Enhanced Vegetation Index (EVI), shortwave radiation data estimated using the Mountain Climate Simulator (MTCLIM) algorithm, and crop-specific LUE per county. The combined aforementioned variables were used to generate spatially-resolved, crop-specific NPP that corresponds to the Cropland Data Layer (CDL) land cover product. Results from the modeling framework captured the spatial NPP gradient across croplands of Iowa and Illinois, and also represented the difference in NPP between years 2006 and 2007. Average corn and soybean NPP from AgI-LUE was 917gCm-2yr-1 and 409gCm-2yr-1, respectively. This was 2.4 and 1.1 times higher, respectively, for corn and soybean compared to the MOD17A3 NPP product. Site comparisons with flux tower data show AgI-LUE NPP in close agreement with tower-derived NPP, lower than inventory-based NPP, and higher than MOD17A3 NPP. The combination of new inputs and improved datasets enabled the development of spatially explicit and reliable NPP estimates for individual crops over large regional extents.

Original languageEnglish
Pages (from-to)61-71
Number of pages11
JournalISPRS Journal of Photogrammetry and Remote Sensing
Volume80
DOIs
StatePublished - Jun 2013

Funding

We thank the US National Aeronautics and Space Administration, Earth Science Division for support of this research under Project NNH08AI06I. We thank Drs. Roser Matamala and Carl Bernacchi for use of flux site data that are distributed via the Carbon Dioxide Information Analysis Center, AmeriFlux Network. We appreciate Drs. Wilfred M. Post, Allison Thompson, and Craig Daughtry for their suggestions and support during this research. We thank Drs. R. Zurita-Milla and B. Bond-Lamberty for critical and helpful reviews of the manuscript. We thank anonymous reviewers for helpful reviews of the manuscript. Pacific Northwest National Laboratory is operated by Battelle for the U.S. Department of Energy under contract DE-AC05-76RL01830.

Keywords

  • Agriculture
  • Carbon flux
  • Crop production
  • Geospatial scaling
  • Phenology
  • Satellite remote sensing

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