Large impacts of climatic warming on growth of boreal forests since 1960.
Boreal forests are sensitive to climatic warming, because low temperatures hold back ecosystem processes, such as the mobilization of nitrogen in soils. A greening of the boreal landscape has been observed using remote sensing, and the seasonal amplitude of CO2 in the northern hemisphere has increased, indicating warming effects on ecosystem productivity. However, field observations on responses of ecosystem productivity have been lacking on a large sub-biome scale. Here we report a significant increase in the annual growth of boreal forests in Finland in response to climatic warming, especially since 1990. This finding is obtained by linking meteorological records and forest inventory data on an area between 60° and 70° northern latitude. An additional increase in growth has occurred in response to changes in other drivers, such as forest management, nitrogen deposition and/or CO2 concentration. A similar warming impact can be expected in the entire boreal zone, where warming takes place. Given the large size of the boreal biome - more than ten million km2- important climate feedbacks are at stake, such as the future carbon balance, transpiration and albedo.
Department of Environmental Sciences, University of Helsinki, Helsinki, Finland; Finnish Forest Research Institute (METLA), Vantaa, Finland.
Pekka E
PE
Kauppi
Coordination Centre for Effects (CCE), National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
Maximilian
M
Posch
Climate Service Centre, Finnish Meteorological Institute, Helsinki, Finland.
Pentti
P
Pirinen
D002245:Carbon Dioxide / Q000032:analysis; D017753:Ecosystem; D005387:Finland; D065928:Forests; D005843:Geography; D057232:Global Warming / Q000266:history*; D049673:History, 20th Century; D049674:History, 21st Century; D012044:Regression Analysis; D014197:Trees / Q000254:growth & development*; D014887:Weather
D002245:Carbon Dioxide