With a warmer climate and fewer grazing domestic animals in the Norwegian mountains, the forests are increasingly moving higher up in the mountains. This means that previously open mountain areas dominated by lichens and heathers are slowly turning into areas dominated by shrubs and mountain forests. Because of this, evapotranspiration from the mountain areas in Norway will increase.

A three-year research project (2025-2027) at the Norwegian University of Life Sciences (NMBU) will investigate the effect of the expansion of the treeline on evapotranspiration. Since evapotranspiration is an important component of the water balance, it is expected that more evapotranspiration will reduce runoff to Norwegian streams and rivers. This in turn could reduce Norway’s future hydropower potential, especially when we know that many of the hydropower reservoirs are in mountainous areas subject to forest migration.

The research project will collect field data on evapotranspiration and soil moisture at Dagali. Four field locations have been established, respectively within coniferous forest, mountain birch forest, shrubs, and lichen heaths.

The data collected will provide an important understanding of differences in evapotranspiration for vegetation above and below the treeline.