Skip to main content

DAAC Home > Data > Regional/Global > Net Primary Production (NPP) > Data Set Documentation
Get Data


Terrestrial net primary productivity (NPP) estimates are compiled from the literature for 34 grasslands, 14 tropical forest sites, and 5 boreal forest sites. These 53 NPP estimates and associated site climate and biophysical characteristics were reviewed and documented to compile a series of web pages containing detailed data and to produce an overview synthesis paper (Scurlock and Olson 2002). This data set consists of the data published in Appendix A Table A.1 of Scurlock and Olson (2002).

The terrestrial net primary productivity (NPP) database at the Oak Ridge National Laboratory Distributed Active Archive Center (ORNL DAAC) ( contains detailed information from over 60 individual intensive study sites in grasslands, tropical forests, and boreal forests. Location, biome type, annual temperature precipitation, and “best estimates” of NPP (aboveground, belowground and total NPP, based upon numbers reported in the literature and the authors' own evaluation) for 53 of these sites are presented here based on Scurlock and Olson (2002). The distribution of intensive study sites is shown in an associated companion file. Of the 53 sites, 29 have data for belowground biomass or biomass dynamics. The earliest NPP data are from 1939, and the most recent, from 1996; the number of years of data for each site ranges from 1 to 51, and 18 sites have data for more than one “treatment” (fertilized or irrigated plots, different soil types, stand ages, etc.). Aboveground NPP ranges from 35 to 2320 g m-2year-1(dry matter), and total NPP, from 182 to 3538 g m-2year-1 (drymatter).

Criteria for selecting “intensive” study sites included the availability of complete and consistent information on NPP or at least partial NPP(components such as litterfall or biomass increment), together with biomass (standing crop of live matter). Site-description metadata, such as latitude, longitude, and elevation, were considered essential for linking the data to model-driving climate variables (which may be interpolated from actual measurement stations to the NPP study sites). Information on vegetation type (biome), soil type, and land-use history was also a prerequisite for inclusion of a study site in the compilation. At least one reference was required from the peer-reviewed literature, although exceptions were occasionally made when the data were well-known in the research community (e.g., unpublished data from the Matador IBP grassland site, Canada).

Quality assurance included cross-checking the NPP records against other compilations of NPP data, eliminating duplicates or documenting multiple treatments at one study site, mapping the points in geographical space to confirm they coincided with the landforms, and checking data ranges for outlying values. The NPP data were provided or discovered in a variety of forms, ranging from tabulated computer text files to graphs from publications or theses. In addition, we communicated with the original authors, or their successors, to ascertain their interest and to seek additional information, data updates and corrections, and permissions.

In common with many types of ecological and environmental data, our criteria for “consistency” included the use of common systems of names (e.g., species, vegetation classes), units of measure, and place names – conversion or translation was needed in many cases. Geographical coordinates were expressed as decimal degrees, although compass directions were retained instead of positive and negative coordinates. In many cases, we had to reconstruct spatial coordinates (latitude, longitude, elevation) from maps, determining the location of an NPP study site from descriptions of its distance from the nearest town or other landmark.

Mean annual average temperature and total precipitation were compiled from the literature source containing the NPP data, when available. In addition, or when no climate data were published, monthly climate data were compiled for each study site to provide 5-100 years of record (precipitation, mean monthly maximum temperature, mean monthly minimum temperature). If possible, these data were obtained from the original literature or the original authors. Alternatively, we obtained the climate data from the nearest weather station (<10 km distant, and at similar elevation) available from existing collections such as the National Climatic Data Center [] (Asheville, NC, U.S.A.) or the Carbon Dioxide Information and Analysis Center [] (CDIAC, Oak Ridge National Laboratory, Oak Ridge, TN, U.S.A.) – see individual site descriptions for details. In some cases, annual mean climatic values were generated from the monthly data, which are available for individual sites on the ORNL DAAC NPP Web site (see below).

Scurlock et al. (2002) examined various methods for estimating NPP from grassland biomass measurements for 31 sites. While that analysis demonstrated a potential bias of NPP estimates depending on which method was used, the grassland NPP estimates presented here rely primarily on the published estimates of NPP.

References for the source of individual site data and NPP estimates for specific years, biomass, climate, and other associated environmental variables for the 53 detailed study sites are available on the ORNL DAAC NPP Web site ( . Many of the sites have data for multiple treatments as well as ancillary information such as site photographs and graphs of biomass dynamics and climate. The total number of site/treatment/year combinations is over 500.

Data Citation:

as follows:

Scurlock, J. M. O., and R. J. Olson. 2003. NPP Multi-Biome: Grassland, Boreal Forest, and Tropical Forest Sites, 1939-1996. Data set. Available on-line [] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.


and R. J. Olson. 2002. Terrestrial Net Primary Productivity--A brief history and a new worldwide database. Environmental Reviews 10:91-109.

Scurlock, J. M. O., K. Johnson, and R. J. Olson. 2002. Estimating net primary production from worldwide extant grassland biomass dynamics measurements. Global Change Biology8:736-748.

Olson, R. J., K. Johnson, D. Zheng, and J. M. O. Scurlock. 2001. Global and Regional Ecosystem Modeling: Databases of Model Drivers and Validation Measurements.ORNL/TM-2001/196. Oak Ridge National Laboratory, Oak Ridge, Tennessee.

Data Format:

The following variables are included in the summary NPP data file from Scurlock and Olson (2002) Appendix A, Table A.1 with additional columns:

Document Information:

February 4, 2003

Document Review Date:

February 4, 2003

Document Curator:

Document URL: