The European Union has decided to reform its agricultural policy, and decouple CAP support partially from production. The aim of this study is to predict diversity effects of agricultural policy reforms in which direct aid payments are disconnected from production, and compare the outcomes with effects of such a policy in which CAP support is coupled. The study employs the dynamic regional sector model of Finnish agriculture. The sector model predicts regional land use, stocking densities, pesticide application areas, and nutrient balances. Diversity of arable land use is measured by Shannon's evenness index which describes diversity at landscape level. The results indicate that if agricultural support is independent from production, the amount of fallow alnd will increase considerably in the future. This will decrease diversity of agricultural land use at landscape level, but may not be harmful at species level since green fallow has some positive effects especially on densities and richness of farmland birds. Instead, the decrease in bovine animals is likely to run down biological diversity, since it simplifies crop rotation and diminishes grazing.