Authors: Gerling, Charlotte; Schöttker, Oliver;Hearne, John;

Climate change causes range shifts of species and habitats, making existing reserve networks less suitable. Reserve networks may be adapted in two ways: by providing additional funds and/or by allowing for the sale of sites to liquidate funds for new purchases. However, due to general negative ecological consequences, selling is often regulated, thus rendering the optimal reserve site selection a problem of irreversible investment. On the other hand, allowing for sale may be interpreted as an investment with costly reversibility, as involved transaction costs do not allow for full recovery of the initial investment. Whether allowing for sale to increase flexibility under climate change outweighs the costs remains an open question. We develop a conceptual climate-ecological-economic model to find the optimal solution for the reserve site selection problem under changing climatic conditions and different policy scenarios. These scenarios differ in terms of whether and when additional funds are provided, and whether selling of sites is allowed. Our results show that the advantage of allowing for sales is large when no additional funds are available and decreases as the amount of additional capital for adaptation increases. Finally, providing a one-off payment initially instead of regular payments improves habitat protection.