An exploratory integrated model to assess management of lake eutrophication

Ecosystem management requires the explicit treatment of interactions betwee n humans and ecosystems. An exploratory model for integrating social and ec ological dynamics was introduced to study ecosystem management strategies. This paper focuses on the management of lake eutrophication. The model was developed to include the dynamics of the lake, the behaviour of agents usin g phosphorus for agricultural purposes, and the interactions between ecosys tem and farmers. Analyses with the model showed that the dominating type of cognitive processing was a relevant factor in the response to uncertainty and policy measures. A higher target level for returns on the use of phosph orus was found to lead to a more intensive use of phosphorus and to higher levels of phosphorus in the lake. Simulated farmers used phosphorus more in tensively in situations with high natural variability. A tax on phosphorus had little effect on the behaviour of the farmers when they felt uncertain and had low target levels for returns. (C) 2001 Elsevier Science B.V. All r ights reserved.