Coarse woody debris quantity and distribution in Central European streams

Summarized here are ten investigations concerning the volume of coarse wood y debris (CWD) in Central European streams. Altogether, 69 stream sections were examined ranging from Northern German lowland streams to brooks in alp ine regions. Most of the study streams are according to Central European st andards quasi-natural and are bordered by deciduous forest. The geometric mean of CWD volume related to stream length is 1.44 m(3)/100 meter reach. Related to stream bottom area, the geometric mean of CWD volum e is 0.202 m(3)/100 m(2). The mean number of logs (greater than or equal to 10 cm diameter) is 12.5 logs/100 meter reach, and 3.01/100 m(2) bottom are a (geometric means). Regarding only quasi-natural stream sections (riparian forest currently unmanaged and no removal of CWD for at least 10 years), t he geometric mean of CWD standing stock is 0.45 m(3)/100 m(2) for lowland s treams, 0.38 m(3)/100 m(2) or streams in lower mountainous areas and 0.02 m (3)/100 m(2) for alpine floodplains. From the distribution of size classes and comparison with other studies it is likely, that the current CWD standing stock is considerably less than th e potential amount of CWD. For centuries all of the streams have been influ enced by man. Historic alterations of the stream, its floodplain and the ri parian vegetation may still affect CWD supply and standing stock. We conclu de that virtually all streams in Central Europe are highly altered with res pect to the amount of CWD, and that the importance of CWD is under-represen ted in recent assessment principles for streams in Germany.