Ecological services from semi-natural habitats originate at different spatial scales. Some services are local, such as production of wood in woodlots or hedgerows. Others have a strong spatial component and require knowledge of processes operating at several square kilometres, such as pest suppression by natural enemies or pollination (Kremen et al. 2007). In addition to the need to understand biological processes at different scales, sustainable reliance on ecological services from semi-natural habitats requires taking into account stakeholders operating at different scales. Retailers, consumers and recreation seekers perceive ecological services at larger scales, because they are interested in larger volumes produced or because the service is associated with the landscape or regional scale, e.g. cultural heritage. Farmers affect ecological performance through field and farm level management, which may be conventional, innovative or organic. In current conventional farming systems there is little active management of semi-natural habitats to protect, exploit and sustain their ecological services. In contrast, innovative and organic farms are heavily dependent on ecological services but these growers, like conventional farmers, would benefit from information to maximise the impact of semi-natural habitat: which type of habitat of which amount of area and in which configuration will enable a desired service (Rusch et al. 2010). Semi-natural habitats which provide ecological services in one agro-climatic zone, may not do so in other agro-climatic zones (Kremen et al. 2007). In conclusion, enhancing ecological services is not a technology waiting to be adopted but requires more knowledge, proof of concept and local adaptation of potential solutions. Science has a role to play by developing simple, robust techniques to measure and predict ecological services across a range of scales, climatic zones and farming systems, by demonstrating synergies and trade-offs among ecological services, and by identifying areas in Europe where investment in semi-natural habitat enhancement would result in greatest benefits. Developing such knowledge and techniques together with local stakeholders provides a sound basis for enhancing credibility and saliency of results, future acceptance of policy measures and impact on the ground.

The Importance of Scale