1. General Model Information

Name: Rain Forest Growth Simulation Model

Acronym: FORMIX

Main medium: terrestrial
Main subject: forestry, biogeochemistry
Organization level: ecosystem
Type of model: not specified
Main application: research, decision support/expert system
Keywords: physiological processes, tropical forest, rain forest, species composition, timber yield, habitat diversity, forest management, grid mode, gap model


Andreas Huth
Center for Environmental Systems Research
University of Kassel
Kurt-Wolters-Strasse 3
D-34109 Kassel
Phone: +49-561-8042496
Fax: +49-561-8043176
Email: huth@usf.uni-kassel.de



The need for reliable assessment of rainforest growth over the long terms and under changing conditions has led to the development of a dynamic simulation model for the growth of tropical rain forest: FORMIX3.

The diversity of tropical rain forest tree species is aggregated in a few, typically five, species groups. Each species group has its own growth process characteristics and its own typical mature height. For each species group the model calculates biomass and tree number in five distinct canopy layers.

Although light parameters and light conditions differ in each layer, the processes in each layer are structurally identical: photoproduction, respiration, shading of lower layers, transitions of trees from lower to higher layers. Photoproduction and respiration rates lead to biomass, diameter, height, and leaf mass growth in each layer. The insolation into a layer, and the leaf mass of trees within the layer determine p hotoproduction of these trees and light conditions in lower layers (competition for light). Mortality of trees is included in the model as random event (including competition for crown space). Large dying trees can fall down and create gaps in the forest. Production of seeds is assumed to produce a constant seed bank and assure continuous seedling establishment.

These concepts are used to model the growth of rain forest in patches of size 20 m by 20 m. Normally a 1 ha stand composed of 25 patches is simulated.

At present, model structure restricts application to evergreen rainforests at sites where no droughts are to be considered and constant climatic conditions throughout the year can be assumed. The development of a site module accounting for soil properties and topography is in progress.

The model was applied to investigate the long-term impact of different logging strategies in different formations of tropical rainforest in Malaysia: mixed dipterocarp forest (MDF) of the lowlands in Sabah, hill MDF in Sarawak and peat swamp forest in Malaysia Peninsula. Complete model documentation, results of comprehensive model testing and an exemplary model application in Sabah including the discussion of simulation results are available (Huth et al. 1996).

II. Technical Information

II.1 Executables:

Operating System(s): DOS and UNIX

II.2 Source-code:

Programming Language(s): Turbo-Pascal, C

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

Huth, A., T. Ditzer and H. Bossel, 1996
Simulation of the growth of tropical rain forest: FORMIX3. Report for the German Agency for Technical Cooperation (GTZ), Eschborn, Germany (project-no.: 89.2143.9- 01.110): 180 pp.

Huth, A., B. Hahn-Schilling and H. Bossel, 1994
Untersuchung der Auswirkungen von verschiedenen Nutzungsstrategien auf das Wachstum von Moorregenwald - Simulationen mit FORMIX. Zeitschrift für Ökologie und Naturschutz 3: 217-225.

Bossel, H. and H. Krieger, 1994
Simulation of multi-species tropical forest dynamics using a vertically and horizontally structured model. Forest Ecology and Management 69: 124-144.

Bossel, H. and H. Krieger, 1991
Simulation model of natural tropical forest dynamics. Ecological Modelling 59: 37-71. 

V. Further information in the World-Wide-Web

Formix Home-Pagin in German and in English .

VI. Additional remarks

Last review of this document by: October, 19th 1997 M.Sonntag
Status of the document:
last modified by Tobias Gabele Wed Aug 21 21:44:43 CEST 2002

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