1. General Model Information

Name: RECAFS 1.0 - Modelling resource competition and cycling in agroforestry systems.

Acronym: RECAFS

Main medium: terrestrial
Main subject: forestry, agriculture, hydrology
Organization level: ecosystem
Type of model: ordinary differential equations
Main application:
Keywords: evapotranspiration, light interception, light consumtion, nitrogen consumtion, trees, planting pattern, Penman-Monteith equation, herbage growth


Ir. J.G. Conijn.
Research Institute for Agrobiology and Soil Fertility (AB-DLO), Dept. Agrosystems Research, P.O.Box 14, 6700 AA Wageningen, THE NETHERLANDS.
Phone: +31.317.475957
Fax: +31.317.423110
email: j.g.conijn@ab.dlo.nl



Basically, the model simulates the absorption of light, water and nitrogen by each species, the dry matter production as a function of the absorbed resources and the effect of resource depletion by both species upon the availability of light, water and nitrogen. The tree population, as described in the model, consists of a number of trees planted in a rectangular planting pattern. The area per tree has been subdivided into 3 subareas and the herbaceous development of each subarea is simulated separately. Light interception by the trees and remaining light availability at ground level for each subarea is simulated and the production of both species is calculated by using the LUE approach. The potential soil evaporation and the potential herb transpiration per subarea are calculated with the Penman-Monteith equation. For simulating the potential tree transpiration, the WUE approach has been applied. Actual water uptake is modelled as a function of soil water status and root length distribution of both species. A simple soil water balance (storage overflow concept) with a number of horizontal layers has been incorporated separately for each subarea. Lateral soil water movement is thus not modelled. Uptake of nitrogen has been related to availability in the soil, root length distribution and the demand for nitrogen of living plant biomass. Net nitrogen mineralization is calculated in dependence of carbon-nitrogen ratios in the soil organic matter. Growth of several plant parts is simulated by partitioning the biomass production of each species among its plant parts. Death of plant parts has also been modelled providing carbon and nitrogen input for the soil organic matter. Modelling objectives are: 1. to predict the herbage growth underneath and outside the tree crown. 2. to simulate the effects of a tree population on water and nutrient availability of the agro-ecosystem. 3. to calculate the production possibilities of a mixed culture of trees and herbs.

Purpose of the model:

Model parentage:

Source of the Abstract CAMASE Register of Agro-ecosystems Models

II. Technical Information

II.1 Executables:

Operating System(s): VAX computer, IBM compatible PC/AT >= 640 Kb RAM; ROM
Contract necessary:
Costs: : Dfl. 270,=.

II.2 Source-code:

Programming Language(s): Microsoft FORTRAN.

II.3 Manuals:

II.4 Data:

III. Mathematical Information

III.1 Mathematics

III.2 Quantities

Rate variables: Light absorption, water uptake, nutrient uptake/partitioning, dry matter production/partitioning, leaf area growth, rooted depth extension, senescence, soil organic matter input (C & N), organic mater decomposition, net nitrogen mineralization, infiltration and redistribution of soil water, soil nutrient flow.

State variables: Dry weight, N content of leaves, stems, roots and generative organs of the herbaceous species for each subarea (3), dry weight, N content of leaves, stems, branches, roots and generative organs of the tree species, leaf area of both species, root length distribution, water and mineral N content per soil layer, C and N content of the soil organic matter.

III.2.1 Input

Geographical latitude, daily weather data, plant and tree density, tree crown size and form, nutrient input rates, morpho-physiological characteristics of tree and herb species, volumetric soil water content at airdry, wilting point and field capacity, initial amount of C and N in soil organic matter, decomposition constants, critical N/C ratios. Input check in model: No.

III.2.2 Output

Values of all state and rate variables and their cumulative values
Time interval of simulation: 1 day.

IV. References

Conijn, J.G. 1997. Inventorization of grass growth simulation models for the benefit of research into carbon and nitrogen flow in grassland.Inventarisatie van grasgroeisimulatiemodellen ten behoeve van het onderzoek naar koolstof- en stikstofstromen in grasland. Report Research-Institute-for-Agrobiology-and-Soil-Fertility. 1997, No. 71, 22 pp.; 1 appendix; 24 ref.., Wageningen

V. Further information in the World-Wide-Web

VI. Additional remarks

Last review of this document by: T. Gabele: Dec 10 1997
Status of the document:
last modified by Joachim Benz Mon Jul 2 18:31:37 CEST 2007

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