Within the NERC/ESRC Land Use Programme ecological change is assumed to be driven principally by agronomic activity. Land use change is defined as being of two types depending on whether there is a complete change of cover or a modification of an existing cover. Some agronomic activities lead to quantitative changes between land cover types and others to more subtle qualitative changes within land cover types. A modelling system based on three distinct models is described for predicting the effects of the two types of change in land cover on the distribution of plants, invertebrates and birds. The potential use of the system in analysing problems of land use change is illustrated using a simple scenario based on changing nitrogenous fertilizer regimes in lowland agriculture.