An interdisciplinary approach for finding biophysically optimal land use strategies with highest social welfare

Agricultural production needs to generate economic profits and contributes to the social welfare of a society. At the same time, it is one of the biggest threats to biodiversity. While from a narrowly economic viewpoint land should be allocated in a way that best fulfils the demand for agricultural products, ecological disciplines aim to protect nature, e.g. biodiversity. Thus, a socially optimal land use strategy should combine both perspectives. However, in the field of spatial land use allocation, there is a lack of studies that consider both aspects simultaneously. Therefore, we developed a method that finds biophysically optimal land use strategies with the highest social welfare by combining methods from mathematics, ecology and economics. We used the Soil and Water Assessment Tool (SWAT) and a biodiversity model to evaluate the biophysical outcomes of different land uses. Additionally, we calculated the profit contribution of agricultural production and the willingness to pay for biodiversity. Then, we coupled the models with the economic information in an optimization framework and determined the optimal solution. An agricultural landscape in Central Germany served as a case study and the results show that in this area, social welfare is mainly defined by a high level of agricultural production. Consequently, any meaningful increase in biodiversity comes along with relatively high losses in agricultural profit. With the combination of methods from three different fields, this study provides an interdisciplinary approach that helps decision makers in finding optimal land use strategies.