Olson's Major World Ecosystem Complexes Ranked by Carbon in Live Vegetation: An Updated Database Using the GLC2000 Land Cover Product (NDP-017b)
In the 1980s, Olson et al. developed a data base and corresponding map following more than 20 years of field investigations, consultations, and analyses of published literature. The original data characterize the use and vegetative cover of the Earth's land surface with a 0.5° × 0.5° grid. The purpose of these world-ecosystem-complex data and the accompanying map were to provide a current reference base for interpreting the role of vegetation in the global cycling of CO2 and other gases and a basis for improved estimates of vegetation and soil carbon, of natural exchanges of CO2, and of net historic shifts of carbon between the biosphere and the atmosphere.
These data were widely used and cited in carbon cycle research. This updated database extends the methodology of Olson et al. to more contemporary land cover conditions of the Global Land Cover Database (GLC2000). The GLC2000 data were developed using remotely sensed imagery acquired in 2000. The updated data are presented in a GIS format and include estimates of mean and maximum carbon density values.
Please refer to the following publication for more information on recent applications of these data: Gibbs, Holly K., Sandra Brown, John O. Niles, and Jonathan A. Foley. 2007. Monitoring and estimating tropical forest carbon stocks: making REDD a reality. Environmental Research Letters 2 045023 (13pp).
This document is an update of Olson, J.S., J.A. Watts, and L.J. Allison. 1985. Major world ecosystem complexes ranked by carbon in live vegetation: A Database. NDP-017, Carbon Dioxide Information Center, Oak Ridge National Laboratory, Oak Ridge, Tennessee. This NDP was originally prepared by R.E. Millemann and T.A. Boden.
This spatially-explicit global data set provides estimates and spatial distribution of the above- and below-ground carbon stored in living plant material, and provides an important input to climate, carbon cycle and conservation studies. The data set was created by updating the classic study by Olson et al. (1983,1985) with a contemporary map of global vegetation distribution (Global Land Cover database; GLC2000).
Source and Scope of the Data
This dataset uses the methodology of Olson et al. (1983, 1985) with a contemporary land cover map (GLC2000) to estimate biomass carbon in vegetation on a global scale. The original Olson data set was derived from vegetation patterns of pre-agricultural vegetation, while this updated data set is based on the land cover conditions in the year 2000 and consequently accounts for human-induced changes in land cover.
Each cell in the gridded data set is coded with a carbon value (metric ton of C per hectare) based upon its land cover class. The gridded data is expressed in decimal degrees, in a geographic projection, with a datum of wgs84. The cellsize for these data is 0.083 decimal degrees.
Applications for the Data
The rates of CO2 release to the atmosphere and its removal from the atmosphere are controlled by factors affecting photosynthesis, respiration, and burning as well as by shifts in land use and climate. An understanding of these relationships together with increased knowledge of the plant pools undergoing change will enhance our ability to integrate information from biology and geography into the geophysical modeling of element cycles and climate.
- The map of Major World Ecosystem Complexes provides a current reference base for interpreting the role of vegetation in the global cycling of CO2 and other gases.
- The data provide a basis for improved estimates of vegetation and soil carbon, of natural exchanges of CO2 and of net historic shifts of carbon between the biosphere and the atmosphere.
Data Limitations and Restrictions
More recent biomass studies supersede Olson's estimates for some regions of the world, but Olson (1983,1985) still provides the only globally-consistent estimate of global carbon stored in vegetation.
While this map represents an improvement over the original Olson (1983) map through improved satellite-based land cover mapping, it does not fully account for the spatial distribution of biomass across the world or within ecosystem complexes. These data represent biomass carbon values at the biome-level and should thus account for major bioclimatic gradients such as temperature, precipitation, and geologic substrate. Biomass, however, varies further within each broad land cover category according to site-level environmental characteristics such as slope, elevation, drainage class, soil type, and land-use history.
Description of Processing Routine
To develop the new data, the Olson land cover classification scheme was translated into the GLC2000 scheme to achieve common land cover classes. First, GLC2000 land cover (glc2000s5m.e00.gz) classes 20 (water) and 23 were set to NODATA (glc2000b.e00.gz). Secondly, broad forest classes from the Food and Agriculture Organization of the United Nations (FAO) global ecological zones map were used to further disaggregate the GLC2000 forest classes into subcategories of boreal, temperate, and tropical dry and humid forest types. Specifically, the 2000 FAO Global Ecological Zones coverage (eco_worldc.e00.gz) was converted to a grid (eco_grid.e00.gz) using the GEZ_TERM variable. Polar/boreal pixels were assigned a value of 1, temperate pixels were assigned a value of 2, tropical pixels were assigned a value of 3, water pixels were assigned a value of 0, and NODATA cells were assigned a value of 15. Thirdly, this grid (eco_grid.e00) was combined with the revised GLC2000 grid (glc2000b) to create a new grid (glceco.e00) containing both land cover class and ecoregion variables for each pixel.
Next, following the assignment of consistent land cover classes, mean and high-end carbon values were applied to each land cover class following the methods of Olson et al. (1983,1985). Specifically, carbon values were assigned to each pixel based upon the combined land cover and ecoregion fields using values contained in Table 4. Please note that if a pixel was coded as water (0) in the ecoregions data yet was classified as a valid land cover class in the GLC2000 data, it was consequently assigned a -9998 in the output carbon grids (with the exception of GLC2000 classes 19,21, or 22 which were assigned a C value of 0 in accordance with the crosswalk table). Furthermore, if pixels were coded as NODATA (15) in the ecoregions grid and were assigned a valid land cover class in the GLC2000 data, they were coded as -9999 in the output carbon grids (with the exception of GLC2000 classes 19, 21, or 22, which were assigned a C value of 0 in accordance with the crosswalk table). Please note that total biomass was converted to carbon assuming a carbon content of 50%. The estimates presented here are for total above- and below-ground biomass, which includes biomass in living trees, litter, and coarse woody debris.
- Olson, J.S., Watts,J.A. & Allison,L.J. 1983. Carbon in live vegetation of major world ecosystems. Oak Ridge National Laboratory, ORNL-5862, Oak Ridge TN.
- Olson, J.S., J.A. Watts, and L.J. Allison, 1985. Major World Ecosystem Complexes Ranked by Carbon in Live Vegetation (NDP-017). Carbon Dioxide Information Center, Oak Ridge National Laboratory, Oak Ridge TN.
- Global Land Cover 2000 Database. European Commission, Joint Research Centre, 2003. http://bioval.jrc.ec.europa.eu/products/glc2000/data_access.php
- FAO Global Ecological Zones are a part of the FAO Global Forest Resources Assessment, 2000. The assessment and related data are available online at [ http://www.fao.org/forestry/index.jsp ] and in print from the Food and Agriculture Organization of the United Nations (FAO), Forestry Department, Rome, Italy.