1. General Model Information
Name: Integrated model of leaf photosynthesis, transpiration, and conductance
Main medium: terrestrial
Main subject: biogeochemistry
Organization level: leaf
Type of model: ordinary differential equations, not specified
Main application: research
Keywords: photosynthesis, transpiration, stomatal conductance, nitrogen, climate change, optimization, Farquhar, Monteith
Institute of Terrestrial Ecology, NERC-ITE
Bush Estate, Penicuick, Midlothian EH26 0QB
PGEN is a detailed model of leaf photosynthesis, respiration, transpiration, stomatal conductance, and energy balance. It was designed for use in larger-scale ecosystem, climate and hydrological models concerned with fluxes of CO2, water, and heat. Given a set of environmental and biological parameters, PGEN calculates instantaneous rates of net photosynthesis and transpiration, and associated conductances to CO2 and water. It is intended to predict species-specific behaviour with minimal need for empirical parameterisation.
The biochemical model of photosynthesis is based on the Farquhar approach. This biochemical model is embedded in a model of the leafs energy balance, which is based on the work of Monteith and Jones. Stomatal conductance is calculated using an optimisation concept. In this concept there is an assumed tradeoff between CO2 entering and water leaving the leaf, resulting in a single stomatal conductance for each set of environmental conditions, that maximises a function including the costs and benefits.
A version of PGEN is used with the general ecosystem model HYBRID .
Abstract taken partly from Friend (1995).
II. Technical Information
Programming Language(s): The source code is available from A. Friend upon request.
III. Mathematical Information
Friend, A.D. 1995. PGEN: an integrated model of leaf photosynthesis, transpiration, and conductance. Ecological Modelling, 77: 233-255.
Kramer, K; Mohren, G.M.J.; Smith, T.M. 1996. Sensitivity of FORGRO to climatic change scenarios: a case study on Betula pubescens, Fagus sylvatica and Quercus robur in the Netherlands. Special issue.The application of patch models of vegetation dynamics to global change issues: papers given at the International Geosphere Biosphere Program workshop held at Apeldoorn, Netherlands, 1994. Climatic-Change. 1996, 34: 2, 231-237; 16 ref.. (FORGRO-PGEN)
Kramer, K. 1995. Modelling comparison to evaluate the importance of phenology for the effects of climate change on growth of temperate-zone deciduous trees. Climate-Research.1995, 5: 2, 119-130; 25 ref.. (FORGRO-PGEN)
V. Further information in the World-Wide-Web
VI. Additional remarks
Last review of this document by: M. Sonntag : October, 19th 1997
Status of the document:
last modified by
Tobias Gabele Wed Aug 21 21:44:47 CEST 2002