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(90-02) Investigating the effects of reduced pesticide usage on farmland plants, insects and birds: Combining monitoring and modelling. Bruus Pedersen, Marianne*,1, Tybirk, Knud2, Axelsen, Jørgen1, Topping, Chris2, Odderskær, Peter2, 1 National Environmental Research Institute, Silkeborg, Denmark2 National Environmental Research Institute, Rønde, Denmark ABSTRACT- The Danish farmers have to reduce the 'treatment index', i.e. the number of times they spray their fields per season with the label rate. This demand has to be fulfilled not by the single farmer, but overall by the farmers in common. The strategy may be either to reduce dosages or to apply the pesticides at a lower frequency. In order to estimate the effects of such reductions on the abundance and distribution of weeds, arthropods and farmland birds, a monitoring programme has been set up to collect data for the development of two modelling tools. Eight times per season, arthropods are sampled by D-Vac in several crops and field boundaries. Concurrently, weed diversity, cover and biomass are sampled within the same plots. All information on pesticide usage and agricultural practice is recorded. The data collected are then utilised by the two models. One model deals with the energetics of direct links between trophic levels, using a 'metabolic pool' approach. In cases where spatial aspects are critical, ALMaSS (Animal Landscape & Man Simulation System), a spatially-explicit agent based model is used. Together, the two models assess the ecological consequences for arable wildlife of changes in the spraying pattern in the different crops. Key words: Pesticide usage, biodiversity, monitoring, models |
