In this thesis, coupling between the delivery of slope material into valley floors and river erosion is considered to be a factor in the evolution of mid-altitude, forested mountains. Analyses of slope-channel interactions were made in ten small catchments with particular emphasis on landsliding-erosion feedback. An original, new dendrogeomorphic approach was applied to determine the cyclic occurrence of landsliding and erosion during recent decades. The results of dendrochronological studies show that the processes studied are strongly interdependent. Fluvial erosion can trigger landsliding by undermining slope bases. Landsliding can intensify erosion by delivering slope material into valley floors. The results of dendrochronological studies have permitted a better understanding of the relief observed in areas where landslides and erosion are coupled. A scheme was established which describes the importance of coupling in the evolution of mid-mountain landscape.