Introduction

The ecosys modelling program is dedicated to the construction and testing of a comprehensive mathematical model ('ecosys ') of natural and managed ecosystems (agriculture, forests, savannah, grassland, tundra, desert). The long-term objectives of this program are to provide a means to anticipate ecosystem behaviour under different environmental conditions (soils, climates and managements). This research program will support planning for the impacts of climate, land use practices and soil management on primary productivity, soil and atmospheric quality and associated resource requirements (e.g. water, fertilizer) of terrestrial ecosystems as part of several national and international research programs.

The design and scope of ecosys are described in general terms below, and further documentation may be found in the cited literature.

  1. Its development is based on the following guidelines:

  2. It is constructed from basic scientific principle using parameters that may be determined independently of the model itself, and that function at spatial and temporal scales smaller than those at which the model is validated.

  3. It is therefore widely applicable, and will offer a predictive capability for ecosystem behaviour with different soils, climates and managements. It integrates temporal scales from seconds to decades, allowing validation vs. data from experiments that range from short-term laboratory incubations to long-term field studies.

  4. It integrates spatial scales ranging from mm to km in 1, 2 or 3 dimensions, as required, allowing the scaling up of microscale phenomena to the landscape level.

  5. It integrates biological scales, both plant and microbial, from the organ to the community, allowing the representation of complex biomes.

  6. It simulates the transport and transformation of heat, water, carbon, oxygen, nitrogen, phosphorus and ionic solutes through soil-plant-atmosphere systems with the atmosphere as the upper boundary and soil parental material as the lower boundary.

  7. It is constructed entirely in FORTRAN, allowing portability among different computers.