This manuscript presents a comprehensive analysis of the eco-hydrology of an Alpine mountain forest. The data series contains monitoring aspects to find effects of the role of fog during mixed rain-fog situations and particularly in an old-grown forest with presence of lichens. This research is a contribution to eco-physiology of forests and their role in regional climate change. The water balance was evaluated of the 2 systems: old forest and young forest. Diverse environmental components were directly measured and calculated to evaluate the effects of fog in old and young forests. The parameters of evapotranspiration were applied separately using time scales and eddy covariance.