A space occupancy model for the vegetation succession that occurs on set-aside

Recent changes in the set-aside scheme in the UK have allowed limited winter grazing of former arable land. The results from field plots show that very different plant communities develop under different cutting and grazing management regimes. A computer model is presented which defines individual plants as three-dimensional entities. The behaviour of these individuals is limited by rules based upon known life-history attributes of the species. However, they have no information about the competitive ability of other species they may encounter. Once defined, the interactions of five different life histories were simulated in three-dimensional arenas in which the environmental parameters could be altered to mimic the experimental treatments applied in the field. This modelling approach was fairly successful in describing five vegetation successions observed in the field. Although many ecological systems undoubtedly operate simultaneously, it is suggested that the descriptive abilities of the modelling approach used may relate to the predominance of a very few systems during the early stages of succession on ex-arable land.