This article discusses the results of a hydrologic five year study performed in two valleys of the Oberharz mountains (Germany). One valley is completely stocked with spruce, whereas in the other valley the forest was clear cut at the start of the investigation.
The measured differences in the run-off of the two valleys are explained as caused by clear cutting, by natural factors which modify meteorologic conditions (although the valleys are located close to each other), and by the inevitable imperfection of measuring.
The opinion is voiced that the denuded soil has preserved over these five years many properties of a forest soil.