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CENTURY: Modeling Ecosystem Responses to Climate Change, Version 4 (VEMAP 1995)


The CENTURY model, Version 4, is a general model of plant-soil nutrient cycling that is being used to simulate carbon and nutrient dynamics for different types of ecosystems including grasslands, agricultural lands, forests, and savannas. CENTURY is composed of a soil organic matter/ decomposition submodel, a water budget model, a grassland/crop submodel, a forest production submodel, and management and events scheduling functions. It computes the flow of carbon, nitrogen, phosphorus, and sulfur through the model's compartments. The minimum configuration of elements is carbon (C) and nitrogen (N) for all the model compartments. The model structures for C, N, phosphorus (P) and sulfur (S) in organic matter are identical; the inorganic components are computed for the specific inorganic compound. Carbon uptake in CENTURY is controlled primarily by nitrogen availability (VEMAP 1995). Elevated CO2 influences net primary production (NPP) predictions by altering the C:N ratio of decomposing organic matter, as well as soil moisture. The soil organic matter sub-model includes three soil organic matter pools (active, slow, and passive) with different potential decomposition rates, above and below ground litter pools, and a surface microbial pool (decomposition of surface litter). The water budget model calculates monthly evaporation, transpiration, water content of the soil layers, snow water content, and saturated flow of water between soil layers. Both plant production sub-models (a grassland/crop sub-model and a forest production sub-model) assume that the monthly maximum plant production is controlled by moisture and temperature, and that maximum plant production rates depend on the availability of nutrients. The grassland/crop production model simulates plant production for different herbaceous crops and plant communities (e.g., warm or cool season grasslands, wheat, and corn). The forest model simulates the growth of deciduous or evergreen forests in juvenile and mature phases. To simulate savanna or shrubland ecosystems, CENTURY combines the grassland and forest sub-models with simulation of nutrient competition and shading effects.

This archived CENTURY 4.0 product has a specialized gridded structure that was designed and used for VEMAP simulations. This version of the model simulates processes on a cell-by-cell basis for each identified cell of interest within the defined grid. There is no inter-cell communication when running the simulations.

The CENTURY Model Version 4.0 embodied the best understanding to date of the biogeochemistry of carbon, nitrogen, phosphorus, and sulfur. The primary purpose of the model was to provide a tool for ecosystem analysis, to test the consistency of data and to evaluate the effects of changes in management and climate on ecosystems. Evolution of the model continued as our understanding of biogeochemical processes improves. The identification of problem areas where processes were not adequately quantified was key to further developments. Model application lead to the identification of needed research and new experimentation to improve understanding.

The CENTURY V4 Users Manual is included as a companion file and more information can be found at:

Results from the VEMAP model simulations can be found in Kittel et al. (2004) at the ORNL DAAC ( ).

Data Citation:

Cite this data set as follows:

Parton, W. J., D. S. Ojima, and D. S. Schimel. 2005. CENTURY: Modeling Ecosystem Responses to Climate Change, Version 4 (VEMAP 1995). ORNL DAAC, Oak Ridge, Tennessee, USA.


VEMAP, et al., J.M. Melillo, J. Borchers, J. Chaney, H. Fisher, S. Fox, A Haxeltine, A. Janetos, D.W. Kicklighter, T.G.F. Kittel, A.D. McGuire, R. McKeown, R. Neilson, R. Nemani, D.S. Ojima, T. Painter, Y. Pan, W.J. Parton, L. Pierce, L. Pitelka, C. Prentice,B. Rizzo, N.A. Rosenbloom, S. Running, D.S. Schimel, S. Sitch, T. Smith and I. Woodward. 1995. Vegetation/ecosystem modeling and analysis project: comparing biogeography and biogeochemistry models in a continental-scale study of terrestrial ecosystem responses to climate change and CO2 doubling. Global Biogeochemical Cycles 9:407-437. (743)

Kittel, T. G. F., N. A. Rosenbloom, T. H. Painter, D. S. Schimel, H. H. Fisher, A. Grimsdell, VEMAP Participants, C. Daly, and E. R. Hunt, Jr. 2004. VEMAP 1: Selected Model Results. Data set. Available on-line [] from Oak Ridge National Laboratory Distributed Active Archive Center, Oak Ridge, Tennessee, U.S.A.

Parton, W.J., D.S. Schimel, C.V. Cole, and D.S. Ojima. 1987. Analysis of factors controlling soil organic matter levels in Great Plains grasslands. Soil Science Society of America Journal 51 :1173-1179.

Metherall, A.K. (1992) Simulation of soil organic matter dynamics and nutrient cycling in agroecosystems, Ph.D. Dissertation, Colo State University, Ft. Collins.

Metherall, A.K., L.A. Harding, C.V. Cole, W.J. Parton (1993) CENTURY Soil Organic Matter Model Environment Technical Documentation, Agroecosystem Version 4.0, Great Plains System Research Unit, Technical Report No. 4. USDA-ARS, Ft. Collins.

Parton, W.J., D.W. Anderson, C.V. Cole, J.W.B. Stewart (1983) Simulation of soil organic matter formation and mineralization in semiarid agroecosystems. In: Nutrient cycling in agricultural ecosystems, R.R. Lowrance, R.L. Todd, L.E. Asmussen and R.A. Leonard (eds.). The Univ. of Georgia, College of Agriculture Experiment Stations, Special Publ. No. 23. Athens, Georgia.

Parton, W.J., D.S. Schimel, C.V. Cole, D.S. Ojima (1987) Analysis of factors controlling soil organic levels of grasslands in the Great Plains. Soil Science Society of America Journal. 51:1173-1179.

Parton, W.J., R. McKeown, V. Kirchner, D. Ojima (1992) CENTURY Users' Manual, Natural Resource Ecology Laboratory, Colorado State University, Ft. Collins.

Robert L. Sanford, Jr.; William J. Parton; Dennis S. Ojima; D. Jean Lodge. 1991. Hurricane effects on soil organic matter dynamics and forest production in the Luquillo Experimental Forest, Puerto Rico: Results of simulation modeling. Biotropica 23:364-372.

Model Product Description:


This specialized version of the model runs simulations on a cell-by-cell basis for each identified cell of interest within the defined grid. There is no inter-cell communication when running the simulations.

The VEMAP simulations of CENTURY were run for the continental U.S using a 1/2 degree grid.

  • midpoint of the upper left hand corner at latitude -124.25, longitude 48.75

  • midpoint of the lower right hand corner at latitude -67.25, longitude 25.25.

  • The VEMAP grid has 48 rows and 115 columns. 3168 cells were simulated.

    Results from the VEMAP exercise can be found at the ORNL DAAC's VEMAP Project page ( ).

    To run a Gridded Century simulation the model expects to read an initialization file named century.init. This driver file contains information about the type of simulation to be run and the location and file names of the input files that will be used to run the simulation. The weather files used for the VEMAP simulations are in netCDF format. The netCDF file is used to obtain the site specific parameters required to run a single grid cell. The soil texture information for a given grid cell is extracted from ASCII files organized by row and column to match the VEMAP grid.

    Target computer platform(s):

    The VEMAP simulations were run on UNIX using a specialized gridded version of the Century 4.0 model.

    Model build environment:

    A Gridded Century spinup simulation will use the lu*.100 files to get the initial information required for a Century simulation. At the end of the spinup simulation the information that is required for initializating a subsequent simulation, run as a extension of the spinup simulation, will be saved in a netCDF file named The initialization information in the file represents the state of the site at the end of the spinup simulation and will be used to set the initial conditions for the subsequent simulations.

    The phase1.ncdf file contains mean weather data for each of the grid cells simulated in the Century VEMAP runs. There is one year of monthly data for each cell. The,, and files contain several years of monthly transient weather for each grid cell. These files hold precipitation, minimum temperature, and maximum temperature values respectively.

    The mbd1_m1.v2, mcl1_m1.v2, and msa1_m1.v2 files contain bulk density, clay, and sand values, respectively, for the VEMAP grid cells.

    When running a VEMAP simulation Gridded Century will write the simulation output to several netCDF files.

    Source code files:

    *.f - Fortran 77 source code files

    *.inc - Fortran include files

    *.c - C source code files

    *.h - C header files

    Makefile_util - Makefile used to build the Century executable on a SUN OS

    Landuse types as defined for the VEMAP simulations:

    lu Description

    1 Tundra

    2 Subalpine Coniferous Forest

    3 Maritime Coniferous Forest

    4 Continental Coniferous Forest

    5 Cool Temperate Mixed Forest

    6 Warm Temperate/Subtropical Mixed Forest

    7 Temperate Deciduous Forest

    10 Temperate Mixed Xeromorphic Woodland

    11 Temperate Coniferous Xeromorphic Woodland

    13 Temperate/Subtropical Deciduous Savanna

    14 Warm Temperate/Subtropical Mixed Savanna

    15 Temperate Coniferous Savanna

    17 C3 Grasslands

    18 C4 Grasslands

    19 Mediterranean Shrubland

    20 Temperate Arid Shrubland

    21 Subtropical Arid Shrubland

    Parameter files:

    crop.100 - grass/crop options

    cult.100 - cultivation options

    fert.100 - fertilizer options

    fire.100 - fire options

    biome specific fix files:

    arcfix.100 - used for landuse type 1

    borfix.100 - used for landuse type 2

    drygfix - used for landuse types 11, 17, 20, and 21

    drytrpfix.100 - used for landuse type 19

    ffix.100 - used for landuse types 3, 4, 5, 6, and 7

    gfix.100 - used for landuse types 13, 14, 15, and 18

    graz.100 - grazing options

    harv.100 - harvest options

    irri.100 - irrigation options

    omad.100 - organic matter addition options

    tree.100 - tree options

    trem.100 - tree removal options

    <site>.100 - landuse type specific site files


















    Sample initialization files: - example century.init file for a spinup run

    century.tran.vveg1940.NoCO2.No24Burn - example century.init file for a transient weather run

    (NOTE: The Gridded Century executable expects to read a file named century.init. These example files would have to be renamed before running the simulation. The VEMAP simulations did not use the nitrogen deposition grid file or the nitrogen deposition scalers file so these files, referenced in the initialization files, are not included in the archive.)

    Weather files:

    phase1.ncdf - mean weather data - transient precipitation - transient minimum temperature - transient maximum temperature

    Soil files:

    mbd1_m1.v2 - bulk density

    mcl1_m1.v2 - clay

    msa1_m1.v2 - sand

    Technical documentation for Century Version 4.0:

    CENTURY V4 Users Manual

    Document Information:


    Document Review Date: