The GPPDI Workshop was held in Cincinnati, U.S.A., December 1996 (Olson et al., 1997).
Summary (September 1996) by Dick Olson and Steve Prince
from Global Change Newsletter No. 27; International Geosphere-Biosphere Programme: A Study of Global Change (IGBP) of the International Council of Scientific Unions
Global modelling and monitoring of net primary production (NPP) is being given high priority in IGBP owing to increasing concern over issues such as the consequences of perturbations in the carbon cycle, the impacts of global land-use change, global climate change, and global food security. Significant advances have been made in process modelling and in the use of remote sensing to monitor global vegetation. The advances in modelling and remote sensing of NPP have highlighted the lack of readily available, reliable information from field studies with which to parameterise and validate the models. The Global Primary Production Data Initiative (GPPDI) is intended to remedy this problem by identifying existing field data sets of primary production and associated environmental data. The programme is using data sets for representative sites, and extrapolating or regionalising the better data sets to grid cells sizes of up to 0.5º x 0.5º. Emphasis is on variables needed to parameterise and validate primary production models, including above and below ground NPP, standing crop, LAI, climate data, site data and landscape variability.
GPPDI was launched following a meeting of ecosystem modellers organized under the IGBP-DIS (Data and Information System), GCTE (Global Change and Terrestrial Ecosystems) and GAIM (Global Analysis, Interpretation and Modelling) programmes at the Potsdam Institute for Climate Impact Research (PIK) in July 1994. The IGBP- DIS Working Paper No. 12 "Global Primary Production Data Initiative Project Description" was presented and adopted at the first full GPPDI Steering Committee meeting in January, 1995 in Paris and further endorsement of the GPPDI given at a Steering Committee meeting held at the Second Potsdam Modelling Workshop in June 1995 (Prince et al., 1995). An international Steering Committee is assisting IGBP DIS to oversee the activity and identify support. A Project Team and Coordinator are implementing the programme. The GPPDI is expected to develop a working data set in two years.
The GPPDI team consists of four components, each undertaken by a separate laboratory having expertise in the appropriate field, as follows: Oak Ridge National Laboratory (ORNL), USA; Geography Department, University of Maryland, USA; Centre d'Études Spatiales de la BIOsphère (CESBIO), Toulouse, France; and PIK, Germany. Work related to the GPPDI has started at the first three institutions as summarized below.
- ORNL (P.I.- Dick Olson) - Under the auspices of the GPPDI and funding from the National Aeronautics
and Space Administration (NASA), the ORNL Distributed Active Archive Center (DAAC) is compiling data from
existing field measurements of net primary productivity (NPP), for a number of major world ecosystem types.
The emphasis is to select global sites that are representative and have very complete data sets. Under
guidance from the GPPDI, the initial NPP database emphasis was on the compilation of grassland datasets and the
initial NPP data is available through the ORNL DAAC (URL http://www-eosdis.ornl.gov/ - look for "NPP" hot keys)
for use by the broader research community. During 1996-97, the NPP data will be supplemented with NPP data
from tropical forests, boreal forests and other existing extensive datasets (e.g. NPP data for 762 sites
compiled by Esser and Lieth for their Osnabrück Biosphere model and the Woodlands Data Set of 117 sites
compiled under the International Biological Program). The data compilation will be performed by a post
doctoral fellow (Jonathan Scurlock) having contacts with the NPP research community. Individuals are
encouraged to review the existing data on the ORNL WWW site and provide comments and suggestions.
- University of Maryland (P.I. - Steve Prince) - The University of Maryland is funded by NASA under
the auspices of the GPPDI to develop fields of NPP data for grid cells between 1 km2 and 0.5º latitude by
0.5º longitude. The work was started in July 1996 and is being conducted by Holly Strand.
- CESBIO (P.I. - Gerard Dedieu) - This component has been identifying large areas of agricultural
crops for which agricultural yield and NPP are available and, when possible, developing NPP and associated
datasets for uniform regions of between 1 km2 and 0.5º latitude by 0.5º longitude. The group
(including Alberte Fischer, CESBIO/PIK, and Sophie Moulin, post-doc at CESBIO) is working on estimating NPP for
two sites in France with initial results expected in late 1996. No funds are currently available to extend the
work to other agricultural systems.
- PIK (P.I. - Wolfgang Cramer) - The PIK group will create data sets of physical variables, including
appropriate point interpolations and area measures, for point sites and areas for which NPP data are obtained.
They plan to initially concentrate on climatology data; however, no funds are currently available for this
component.
Steve Prince, Department of Geography, University of Maryland, Lefrak Hall, Room 1113, College Park, MD 10742-8225 U.S.A.
References
Prince, S.D., R.J. Olson, G. Dedieu, G. Esser, and W. Cramer (1995) Global Primary Production Data
Initiative Project Description. IGBP-DIS Working Paper No. 12, IGBP-DIS, Toulouse, France.
Olson, R.J., J.M.O. Scurlock, W. Cramer, W.J. Parton and S.D. Prince (1997)
From Sparse Field Observations to a Consistent Global Dataset on
Net Primary Production. IGBP-DIS Working Paper No. 16, IGBP-DIS, Toulouse, France.