A MODEL OF BRACKEN (PTERIDIUM-AQUILINUM) GROWTH AND THE EFFECTS OF CONTROL STRATEGIES AND CHANGING CLIMATE

1. A mechanistic physiological model for the growth of bracken has bee n developed which describes its yearly cycle in terms of three compart ments: frond biomass, rhizome tissue biomass and rhizome carbohydrate. 2. Difference equations for various processes (including rhizome resp iration, tissue senescence, photosynthesis and fluxes between compartm ents) are presented. 3. These are combined to obtain equations for the three compartments for each stage in the yearly cycle of bracken grow th. Collectively, these equations constitute the bracken growth model. 4. The model can be used to predict the effects of different control measures on the biomass present in the stand. 5. As a number of enviro nmental factors are involved in the model, the effects of changes in t hese variables can be predicted. 6. The deficiencies of the model are discussed and these emphasize areas where research on bracken should b e focused.