Consequences of climate change in combination with air pollution for ecosystem services are multiple but hard to predict. To meet future challenges, a way forward is development of supersites in forest research. This chapter will elucidate the development of existing European forest monitoring and research infrastructures, describe harmonisation of databases and knowledge about climate change and air pollution impact on forest ecosystems and present knowledge gap statements from fifty experts affiliated with the COST FP0903 Action. The statements are structured within the following subjects: The carbon cycle in forests (LULUCF accounting), forest health and vitality, forest biodiversity, extent of forest resources, availability of wood and forest biomass, protective functions of forests and socio-economic information about the forest sector. This will provide a base of knowledge with regard to supersites in forest ecosystem monitoring and research.

Conclusions from the individual chapters are integrated into a synopsis, covering achievements and perspectives, and linking challenges for natural and social sciences, provisioning ecosystem services (ESs) under environmental change. The required research and policy making are facilitated by novel understanding of ecosystem functioning and internal factorial interactions with the atmosphere. A basis is provided through methodological progress for establishing forest research ‘supersites’ within global research networks, possessing capacities for creating generic mechanistic knowledge of ecological relevance. On such grounds, provisioning versus regulating ESs must accommodate diversification in the joint production of agricultural and forestry goods, backed by integrative bioeconomic land-use modelling. Advancement requires forest ecosystem-level unification of air pollution and climate change research while strengthening communication between experimentalists, monitoring experts, modellers, policy makers and stakeholders towards tool development for reliable risk assessment. A critical and appreciative view of forest functions and services is demanded in relation to the (post-)Kyoto debate.

This chapter outlines the aims and scope of the book. An introduction is given to the current status of knowledge which is presented on the topic of the book. Arguments are presented for writing the book, in view of continued, long-term and process-based research needed for mitigating ecological and socio-economic risks to forests under global change. The book will conclude on suggestions for decision making and reasons for continued funding of related research.

Untangling the complex effects that different air pollution and climate change factors cause to forest ecosystems is challenging. Supersites, that is, comprehensive measurement sites where research and monitoring of the whole soil–plant–atmosphere system can be carried out, are suggested as a refinement of the current monitoring and research efforts in Europe. This chapter identifies and discusses key measurements to be carried out at such supersites, with a focus on four topical subjects: the carbon, nitrogen, ozone and water budgets. This kind of holistic approach is vital to a realistic translation of the ongoing changes in climate and air quality into research on the impacts on forest ecosystems. Such an integrated effort requires a considerable use of resources at highly instrumented measurement sites and can only be achieved by building on existing infrastructures.