Perception and evaluation of dead wood in streams and rivers by German students

Dead wood is a significant element of natural streams and rivers in temperate climate zones. Established stream management removes wood, whereas some scientists recently promoted the reintroduction of wood in stream rehabilitation and restoration. It is desirable to know if wood in streams and rivers would be accepted. A survey was therefore conducted in order to assess the spontaneous visual perception of 10 stream and 10 river scenes with and without wood in terms of naturalness, risk, aesthetics and need for improvement using visual analog scales. Three hundred and sixty-five German students from five subjects related to water management and from one subject without any professional association to running waters were surveyed before their first contact to teaching of aquatic ecology. They clearly perceived wood in streams and rivers as natural. Scenes with wood were most frequently associated with danger for sport activities while scenes without wood were most frequently associated with danger by flooding. When comparing scenes with and without wood, scenes with wood were clearly considered more positive as significantly more aesthetic, less dangerous and needing less improvement. The disciplinary groups showed variations in the absolute evaluation scores but the relative evaluation of scenes with wood versus scenes without wood was similar among all groups. The results indicate an acceptance for the reintroduction of wood in stream rehabilitation and restoration by young students who are potential future players in water management.