Effects of budget constraints on conservation network design for biodiversity and ecosystem services

• We model expansion of a conservation network for biodiversity and ecosystem services.
• Biodiversity targets are not adversely affected by including ecosystem services in planning.
• Including ecosystem services in the network moderately changes priority areas.
• Stepwise budget allocation decreases cost-effectiveness of a conservation network.

Limited budgets and budget cuts hamper the development of effective biodiversity conservation networks. Optimizing the spatial configuration of conservation networks given such budget constraints remains challenging. Systematic conservation planning addresses this challenge. Systematic conservation planning can integrate both biodiversity and ecosystem services as conservation targets, and hence address the challenge to operationalize ecosystem services as an anthropocentric argument for conservation. We create two conservation scenarios to expand the current conservation network in the Dutch province of Limburg. One scenario focuses on biodiversity only and the other integrates biodiversity and ecosystem services. We varied conservation budgets in these scenarios and used the software Marxan to assess differences in the resulting network configurations. In addition, we tested the network’s cost-effectiveness by allocating a conservation budget either in one or in multiple steps. We included twenty-nine biodiversity surrogates and five ecosystem services. The inclusion of ecosystem services to expand Limburg’s conservation network only moderately changed prioritized areas, compared to only conserving biodiversity. Network expansion in a single time-step is more efficient in terms of compactness and cost-effectiveness than implementing it in multiple time-steps. Therefore, to cost-effectively plan conservation networks, the full budget should ideally be available before the plans are implemented. We show that including ecosystem services to cost-effectively expand conservation networks can simultaneously encourage biodiversity conservation and stimulate the protection of conservation-compatible ecosystem services.