1. General Model Information
Name: Canopy photosynthesis model
Main medium: terrestrial
Main subject: biogeochemistry
Organization level: leaf, canopy
Type of model: 2D
Keywords: photosynthesis, crown,canopy, transpiration,radiation interception
Department of Biological Sciences
MAESTRO/MAESTRA is a model of forest canopy radiation absorption and photosynthesis. The model has a long history, going back to the work of Norman & Jarvis in the 1970's and 80's. Ying Ping Wang improved and tested the model for his PhD thesis, and it was published in Wang & Jarvis (1990) Agric For Meteorol 51:257-280. A lot of other people have worked on the model over the years, and as of 1997 there were several versions of the model in existence, most of which were complicated and difficult to understand or modify.
For the purposes of the ECOCRAFT project, B. Medlyn revised a version of the
MAESTRO model which she obtained in early 1997 from Ying-Ping Wang.
The revised model was renamed to MAESTRA. The major revisions included:
- removing redundant and spaghetti code;
- modularising the code to make the program easier to understand and modify;
- incorporating standard formulations of physiological sub-modules
(Farquhar - von Caemmerer, Ball-Berry).
Abstract taken from the MAESTRA home page with minor changes.
- The forest canopy is represented in the model as an array of tree crowns, whose positions and dimensions are specified.
- Calculations are done for just one crown, the 'target crown.
- The distribution of leaf area within the target crown is specified, as is the leaf angle distribution.
- The main meteorological driving variables are incident radiation, temperature and humidity.
- The target crown is divided into up to120 grid points, and the radiation penetrating to each grid point is calculated for three wavebands (PAR, near infra-red and longwave). Direct, diffuse, and scattered radiation are considered separately.
- The absorbed PAR at each grid point drives the photosynthesis and transpiration routines.
- Photosynthesis is calculated from the Farquhar-von Caemmerer model.
- Stomatal conductance can be calculated from either of the Jarvis, Ball-Berry, or Ball-Berry-Leuning models.
- Transpiration is calculated by applying the Penman-Monteith equation at each gridpoint, and summing over the gridpoints.
II. Technical Information
MAESTRA home page (see section: download).
Programming Language(s): Fortran
Source code, executables and manuals are available from the MAESTRA home page.
III. Mathematical Information
Wang, Y.-P. and Jarvis, P.G. 1990.
Description and validation of an array model . MAESTRO. Agric. For. Meteorol. 51 : 257-280.
Wang, Y.-P.; McMurtrie, R.E.; Landsberg, J.J. 1992.
Modelling canopy photosynthetic productivity. In: Baker, N.R. and H. Thomas (eds) Crop photosynthesis: spatial and temporal determinants. Elsevier Science Publishers B.V. p. 43-67.
V. Further information in the World-Wide-Web
MAESTRA home page.
VI. Additional remarks
Last review of this document by: M. Sonntag : October, 19th 1997
Status of the document:
last modified by
Joachim Benz Fri Apr 20 13:26:59 CEST 2007