Generation of a Consistent Terrestrial Net Primary Production Data Set

Principal Investigator: Dr. Prince

This proposal is to continue our contribution to the International Geosphere-Biosphere Program (IGBP) Data and Information System (DIS) Global Primary Production Data Initiative (GPPDI), a coordinated, international program to improve global estimates of terrestrial net primary production (NPP) for parameterization, calibration and validation of NPP models. The first part of this strategy was to develop a reference database of existing field measurements of net primary production (NPP). Significant progress has been made in compiling existing, suitable NPP data for grasslands, boreal forests, and tropical forests as well as documenting several, large existing NPP data collections and archiving these in the Distributed Active Archive Center (DAAC) for Biogeochemical Dynamics at Oak Ridge National Laboratory (ORNL). The next logical step to continue this important activity is to develop gridded NPP data sets that can be easily used by the global modeling community. We propose to accomplish this by applying methodologies that were developed at three international workshops during the first phase of funding. These work-shops attempted to establish the very best procedures and it is now proposed to put these procedures into practice and to develop a working data set of NPP for grid cells suitable for model validation. In addition, we propose to continue to compile high quality field NPP data with complete documentation for key sites in a range of biomes, especially those with high priority as determined by the NPP modeling community.

The proposed work will be conducted in collaboration with a parallel proposal by Dick Olson and Jonathan Scurlock of Oak Ridge National Laboratory. The ORNL component will emphasize point NPP data and forest and grassland systems. While the UMD component will emphasize 0.5 degree grid-cell NPP data and crop systems. Both groups are using consistent methodologies and will organize and participate in international meetings that will review data and documentation, review the scaling of NPP to grid cells, and facilitate the use of the NPP data in modeling and analysis. Data from both groups will be submitted to the ORNL DAAC for distribution and archiving.

Currently, the grid-cell NPP data set consists of 2889 cells developed from 11 different sources worldwide including cropland (220), forestland (583), and grassland (2086). About 98% of the cells are located in the U.S. More data from west Africa, Australia, and Europe are expected.