Forest environmental monitoring (ForUm) goes back to the forest damage research in the 1980s. In Germany, the assessment of “new types of forest damage” began in 1982. In 1984, the forest condition survey was carried out as a sample survey for the first time throughout what was then Germany and West Berlin. The crown and tree condition are recorded as an indicator of stress on forest ecosystems and the vitality of the trees.

In 1994, the annual forest condition survey, based on a systematic sampling grid, was supplemented by intensive forest environmental monitoring (Level-II) on selected monitoring sites. This programme is designed to record stress and risks in a timely manner and to clarify cause-effect relationships. This includes influences on the forest condition as well as reaction patterns of the forests. Level II monitoring is based on long-term research sites, measurements and methods from forest ecosystem research, so that the longest time series of German forest environmental monitoring in the Solling, for example, go back to the 1960s.

European forest monitoring was established at the same time as forest environmental monitoring in Germany. In 1979, the United Nations Economic Commission for Europe (UNECE) signed the Convention on the Control and Monitoring of Long-range Transboundary Air Pollution (CLRTAP) in response to large-scale sulphur and acid deposition in Scandinavian lakes and forests in Central Europe (“new types of forest damage; forest dieback”). This convention, also known as the Geneva Convention on Air Pollution, came into force in 1983 as an international treaty. Under its framework, the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) was established in 1985. Germany still holds the presidency and maintains the International Programme Coordination Center (PCC) at the Thünen Institute of Forest Ecosystems.

In 1986, the European Community issued Regulation (EEC) 3528/86 to protect forests against air pollution. In addition to monitoring regulations, which adopted the survey procedures developed in Germany and at ICP Forests, it also provided for co-financing of ICP Forests. It was followed by several subsequent regulations, most recently Regulation (EC) No. 2152/2003 on the monitoring of forests and environmental interactions in the Community (Forest Focus). Since its expiry and the associated discontinuation of co-financing, responsibility for forest environmental monitoring has largely been transferred tothe member states.

Based on the data from forest environmental monitoring, national and international environmental policy measures have effectively reduced the input of sulphur into forests. In addition, the adaptability of forests has been significantly increased through changes in forest management. Continued high nitrogen inputs and ozone concentrations, a changing climate and the decline in biodiversity are important challenges that forest environmental monitoring must continue to face and has already successfully adapted to a large extent.