1. General Model Information

Name: Vegetation Model

Acronym: VEGOMAT


Main medium: terrestrial+air
Main subject: biogeochemistry
Organization level: ecosystem
Type of model: individual-based, not specified
Main application:
Keywords: vegetation model, linking models, trees, shrubs, grasses, environmental conditions, gap model, spatial scales

Contact:

W. K. Lauenroth
D. P. Coffin

H. H. Shughart; T. M. Smith
Environmental Sciences Departement
University of Virginia, Charlottesville
Virginia USA.

T. B. Kirchner
Natural Resource Ecology Laboratory
Colorado State University, Fort Collins
Colorado 80523, USA.


Author(s):

Abstract:

VEGOMAT (Smith et al. 1989) is a framework for linking individual-based gap models which can operate simultaneously at number of spatial scales. The prototype version operates at three spatial scales corresponding to plot sizes for simulating the dynamics of herbs, shrubs and trees. Each spatial scale operates as a seperate submodel; these interface via plant influence on environmental conditions and the process of recruitment. The largest spatial scale corresponds to a gap-model plot for trees, with progressively smaller plots for shrubs and grasses. The plots are nested in that each of the smaller plots is a sub-plot of the plot at the next larger scale, thus maintaining the spatial context of nestedness: the shrub plots can be viewed as samples within the larger tree plot, and similarly the grass plots as samples within the shrub plots.
The vertical profile is continuous, with a defined minimum and maximum height for each spatial scale (submodel). Each scale operates as a conventional gap-model; however, as individuals grow they can pass from one scale to the next larger as they increase in height. This process of recruitment from one scale to the next is carried out as a probabilistic process based on sample statistics for replicate plots at the next lower level. In turn, the large plots act as a constraint on the small next lower level. In turn, the large plots act as a constraint on the small scales by modifying the environmental conditions of plots within them. For example, the available light at the top of the vertical profile for a shrub plot is defined by the leaf area of the larger tree plot to which it belongs. Thus, the framework is one of the large plots acting as a context for the small, and the small plots providing a statistical distribution of recruitment to the large.

(from : Lauenroth, W.K.; Urban, D.L.; Coffin, D.P.; Parton, W.J.; Shugart, H.H.; Kirchner, T.B.; Smith, T.M.; 1993 : Modeling vegetation structure - ecosystem process interactions across sites and ecosystems. Ecological Modelling (67), P. 49 - 80.)


II. Technical Information

II.1 Executables:

Operating System(s):

II.2 Source-code:

Programming Language(s):

II.3 Manuals:



II.4 Data:



III. Mathematical Information


III.1 Mathematics


III.2 Quantities


III.2.1 Input

III.2.2 Output


IV. References

Lauenroth, W.K.; Urban, D.L.; Coffin, D.P.; Parton, W.J.; Shugart, H.H.; Kirchner, T.B.; Smith, T.M.; 1993 :Modeling vegetation structure - ecosystem process interactions across sites and ecosystems. Ecological Modelling, (67), P. 49-80.


V. Further information in the World-Wide-Web


VI. Additional remarks

Under xeric conditions, or on mesic sites following disturbance, the model structure is one of independent replicate plots at the smallest scale, and is roughly equivalent to the STEPPE model.Under wetter site conditions or as succession proceeds on mesic sites, woody plants become established and grow. As these individuals increase to a size corresponding to the next largest scale the structure of the model becomes one of a sample of intermediate scaled plots and a series of smaller scale plots nested within. This continues until trees dominate, with the shrub and herbaceous/woody seedling plots representing subsamples of the large forest plot. For closed canopy forests, VEGOMAT should approximate ZELIG; for dry grasslands it should approximateSTEPPE.Thus, this single modeling framework can simulate a range of conditions from grassland to forest using the same model paradigm, and bridges STEPPE and ZELIG. (from : Lauenroth, W.K.; Urban, D.L.; Coffin, D.P.; Parton, W.J.; Shugart, H.H.; Kirchner, T.B.; Smith, T.M.; 1993 :Modeling vegetation structure - ecosystem process interactions across sites and ecosystems. ecological Modelling (67), P. 49 - 80).
Last review of this document by: T. Gabele: Thu Sep 18 1997
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:52 CEST 2002

Go back to Register of Ecological Models (R E M)