instream wood, headwater stream, wood mobility, Moravskoslezské Beskydy Mts

We inventoried instream wood in the 0.4 km long Mazák headwater channel in the protected area of the Mazácký Gruník natural monument, Moravskoslezské Beskydy Mts. The studied channel (2<W<4.5 m; 0.20<S<0.40 m/m) was confined by very steep adjacent hillslopes (0.6<S<1.1 m/m). The total number of inventoried instream wood was 90 LWs and 199 SWs. Almost all investigated pieces were European beeches (Fagus sylvatica L.) and only two pieces were Norway spruces (Picea abies (L.) Karst.). We assessed the parameters of wood dimensions, orientation, decay status (four classes), stability (unattached/in contact with hillslopes/attached by bed sediments or other wood), % of influenced channel width by a wood, the geomorphic function of a wood (step, wood jam) and % of length of a wood in channel. In addition, dendrogeomorphic dating of 36 LWs and 17 SWs was performed to obtain residence time of instream wood and to provide some insights into its mobility. The results demonstrated a local increase in the number of LWs in channel-reaches confined by the steepest adjacent hillslopes (especially at 0.15-0.20 km). Increasing downstream amount of SW most likely reflected wood transport dynamics in the stream, and the later deposition of SWs on the lowest channel gradients. Also LWs and SWs in the downstream channel-reaches were more decayed than wood presented in the upper reaches