Dynamic modeling of ecosystems with spatial heterogeneity. A structured approach implemented in Windows environment

A computer software tool, spamod, is developed under Microsoft Windows environment for modeling ecosystems with spatial heterogeneity at Institute of Botany, The Chinese Academy of Sciences. The package consists of four independent programs: spagis, spadef, sparun and spasta. spagis is the interface with Geographical Information System. It takes the rastered category data from GIS as input and converts into either category or continuous data of desired resolution. spadef allows users to specify or define model structure, translates the model into standard C module, compiles and links the model to sparun, the runtime environment of spamod. sparun runs the model interactively with the user and displays the result graphically and in text file. Finally, spasta analyzes and summarizes the modeled spatial patterns for important conclusions drawn from the modeling result. are defined as hierarchical structures in spadef. spadef also allows users to define disturbances to the system in three different ways: (1) as forcing functions to system variables; (2) as Kronecher delta functions; and (3) as dynamic control. In addition to working as a system equation solver, sparun is especially equipped with the capability to parameterize and calibrate the model if an observed time series of the spatial patterns for the system variables is available. ckage takes the advantage of superior feature of Microsoft Windowsʹ memory management, device-independent graphical capability and friendly and flexible user interface. spamod is a feasible alternative for spatial simulation with microcomputers and workstations.