In 2007, Forest Research Institute of Karelian Research Centre of RAS joined the International Co-operative Programme on Assessment and Monitoring of Air Pollution Effects on Forests (ICP-Forests), which is now one of the world's biggest biomonitoring systems. The data obtained are comparable with data from other countries, so that necessary comparisons and conclusions can be drawn. The indices determined according to ICP-Forests techniques are used to assess the state of forests, the carbon cycle and biological diversity, to fulfill international commitments. We suggest that the newly established monitoring network is viewed as the basis for developing ecological studies in Republic and that the materials are used for comparative analysis of nature use in Еuropean countries and Karelia on forest ecosystems.