ADAPTING GEPSI (GENERIC PLANT SIMULATOR) FOR MODELING STUDIES IN THE JASPER-RIDGE CO2 PROJECT

In order to conduct modeling studies on the effects of elevated atmosp heric carbon dioxide concentration ([CO2]) on plant and ecosystem proc esses at the Jasper Ridge grassland in northern California, the generi c plant simulator (GePSi) (Chen: J.-L. and Reynolds, J.F., 1997. Ecol. Model., 94: 53-66), is modified to simulate grass dynamics. This modi fication was attempted by the authors of this paper, who had no prior experience with the model. Prior to this project, GePSi, which is impl emented in the object-oriented programming (OOP) language, C++, had on ly been used to model trees and woody shrubs. This exercise addressed several of the concepts presented in this volume concerning the purpor ted benefits of genericness, modularity, and OOP in plant modeling. Th e objective of this paper is to briefly summarize the extent to which these benefits were realized and some of the problems encountered. Our evaluation is presented in terms of: (1) design considerations, inclu ding the importance of how the modules in GePSi were defined; and (2) the implementation phase, which critiques the use of OOP for facilitat ing the transfer of the model. This study suggests that generic, modul ar models such as GePSi will facilitate the interactions of model deve lopers and users and reduce duplication of effort in model development . (C) 1997 Elsevier Science B.V.