Influence of large woody debris on the morphology of six central European streams

The impact of large fallen trees on channel form is described for six short stream sections in central Europe influenced by large woody debris (LWD sections), five of which are compared to nearby reference sections free of LWD (reference sections). Three-dimensional models of streambed topography were generated by surveying cross-sections with a spacing of 1 per 1/15 channel width. Parameters derived from digital terrain models and cross-sections compared between LWD sections and reference sections include the extent of pools, bars, and cutbanks, streambed and bank complexity, cross-sectional area, width, depth, and cross-section complexity as described by Andrle's [Math. Geol. 26 (1994) 83] ‘angle-measurement-technique’ (AMT analysis), a measure of the deviation of a cross-section line from a straight line. Structural diversity is greater in LWD sections at almost all spatial scales, particularly in terms of pool volume (Mann–Whitney U-test, p<0.01) and cross-section complexity described by median angle of AMT analysis (Mann–Whitney U-test, p<0.05). Large pools are clearly associated with large fallen trees and attain volumes up to 36 m3. With the exception of the ratio of one LWD section where the fallen tree is oriented parallel to flow, the ratio of pool volume to bed planimetric area ranges from 424 to 693 m3/ha, which is in the upper range reported for small, high-gradient streams in Oregon, NW America (229–755 m3/ha) [Can. J. Fish. Aquat. Sci. 47 (1990) 1103]. Pool volume of LWD sections is strongly correlated to the blockage ratio (Spearman rank order correlation, rs=0.93, p<0.01). Differences in channel morphology between the LWD sections and reference sections indicate a strong morphologic control of large woody debris in these central European stream sections.

[1]  Robert Andrle,et al.  The angle measure technique: A new method for characterizing the complexity of geomorphic lines , 1994 .

[2]  M. Bryant.  The Role and Management of Woody Debris in West Coast Salmonid Nursery Streams , 1983 .

[3]  S. Trimble,et al.  Stream channel erosion and change resulting from riparian forests , 1997 .

[4]  D. Hogan.  The influence of large organic debris on channel recovery in the Queen Charlotte Islands, british Columbia, Canada , 1987 .

[5]  L. B. Leopold,et al.  River flood plains: Some observations on their formation , 1957 .

[6]  M. L. Murphy,et al.  Effects of Clear-cut Logging with and without Buffer Strips on juvenile Salmonids in Alaskan Streams , 1986 .

[7]  R. Beschta,et al.  Characteristics of Coarse Woody Debris for Several Coastal Streams of Southeast Alaska, USA , 1990 .

[8]  P. E. Porter,et al.  Effects on bedload transport of experimental removal of woody debris from a forest gravel‐bed stream , 1993 .

[9]  John M. Nestler,et al.  Describing scales of features in river channels using fractal geometry concepts , 2000 .

[10]  F. Swanson,et al.  Dynamics of large woody debris in streams in old-growth Douglas-fir forests , 1987 .

[11]  R. Beschta,et al.  Coarse woody debris and channel morphology interactions for undisturbed streams in southeast Alaska, U.S.A. , 1990 .

[12]  K. Richards,et al.  Developments in monitoring and modelling small‐scale river bed topography , 1994 .

[13]  R. Bilby.  Role of Organic Debris Dams in Regulating the Export of Dissolved and Particulate Matter from a Forested Watershed , 1981 .

[14]  T. Quinn,et al.  Summer Distribution, Survival, and Growth of Juvenile Coho Salmon under Varying Experimental Conditions of Brushy Instream Cover , 1995 .

[15]  Henry A. Froehlich,et al.  Woody debris, channel features, and macroinvertebrates of streams with logged and undisturbed riparian timber in northeastern Oregon, U.S.A. , 1990 .

[16]  A. Elosegi,et al.  Woody Debris in North Iberian Streams: Influence of Geomorphology, Vegetation, and Management , 2001, Environmental management.

[17]  F. Swanson,et al.  Effects of coarse woody debris on morphology and sediment storage of a mountain stream system in western Oregon , 1993 .

[18]  Peter Calow,et al.  The River's handbook: hydrological and ecological principles. Vol. 1 , 1993 .

[19]  D. Montgomery,et al.  LARGE WOODY DEBRIS JAMS, CHANNEL HYDRAULICS AND HABITAT FORMATION IN LARGE RIVERS , 1996 .

[20]  R. Beschta.  Debris Removal and Its Effects on Sedimentation in an Oregon Coast Range Stream , 1979 .

[21]  Michael K. Young,et al.  Summer movements and habitat use by Colorado River cutthroat trout (Oncorhynchus clarki pleuriticus) in small, montane streams , 1996 .

[22]  E. Keller,et al.  Stream channel response to the removal of large woody debris , 1987 .

[23]  D. Hering,et al.  Coarse Woody Debris Quantity and Distribution in Central European Streams , 2000 .

[24]  A. Lemly,et al.  Effects of large woody debris placement on stream channels and benthic macroinvertebrates , 1997 .

[25]  Gordon E. Grant,et al.  When do logs move in rivers? , 2000 .

[26]  K. Gregory,et al.  Interactions between semi-natural vegetation and hydrogeomorphological processes , 1995 .

[27]  C. Townsend,et al.  Distribution and abundance of coarse woody debris in some southern New Zealand streams from contrasting forest catchments , 1993 .

[28]  Marc Gerhard,et al.  Restoration of Streams with Large Wood: Effects of Accumulated and Built-in Wood on Channel Morphology, Habitat Diversity and Aquatic Fauna , 2000 .

[29]  F. Swanson,et al.  EFFECTS OF LARGE ORGANIC MATERIAL ON CHANNEL FORM AND FLUVIAL PROCESSES , 1979 .

[30]  K. Fausch,et al.  Large Woody Debris and Salmonid Habitat in a Small Coastal British Columbia Stream , 1992 .

[31]  B. Finlayson,et al.  Hydraulic guidelines for the re-introduction and management of large woody debris in lowland rivers , 1996 .

[32]  K. Gregory,et al.  The permanence of debris dams related to river channel processes , 1985 .

[33]  J. A. Milne,et al.  Modelling River Channel Topography Using GIS , 1997, Int. J. Geogr. Inf. Sci..

[34]  David R. Montgomery,et al.  Effects of hydraulic roughness on surface textures of gravel‐bed rivers , 1999 .

[35]  H. Piégay,et al.  Input, storage and distribution of large woody debris along a mountain river continuum, the Drôme River, France , 1999 .

[36]  M. Mosley.  The influence of organic debris on channel morphology and bedload transport in a New Zealand forest stream , 1981 .

[37]  R. Beschta,et al.  COARSE WOODY DEBRIS AND CHANNEL MORPHOLOGY: A FLUME STUDY1 , 1989 .

[38]  Gordon E. Grant,et al.  Transport and deposition of large woody debris in streams: a flume experiment , 2001 .

[39]  C. Andrew Dolloff,et al.  Design Considerations for Large Woody Debris Placement in Stream Enhancement Projects , 1998 .