Spatial ecosystem modelling using parallel processors

Abstract

We have developed a spatial modeling workstation, that consists of a combination of hardware and software tools that allow development, implementation and testing of spatial ecosystem models in a convenient desktop environment. The system links commercially available Geographic Information Systems (GIS) for managing spatial data with a commercially available general dynamic simulation system for developing unit models (STELLA TM) and a Spatial Modeling Package (SMP) that we developed for linking the unit models into a spatial array, handling horizontal exchanges, and running the array as a spatial model. The spatial model code is executed on either: (1) transputers (parallel processors) resident in a desktop microcomputer; or (2) on a remote Connection Machine parallel mainframe computer with 64 K processors. Resulting time series maps are readable by the GIS system for further display and analysis. In this paper we: (1) describe the hardware and software system; (2) describe a hypothetical model of simple diffusion over a landscape that we developed and tested using the system; and (3) describe a practical application of the system to spatial modeling of long-term habitat succession in the coastal Louisiana region. We find that a system using eight transputers on a Macintosh IIci can run spatial ecosystem models in about the same time asa CRAY X/MP.