C. E. Millington’s research while affiliated with Edinburgh Cancer Research and other places

The role of wood in the formation and maintenance of complex dynamic floodplain surfaces is important and to date has received relatively limited attention compared to in-channel habitat processes. This paper explores the role of logjams as important agents of channel:floodplain interaction. We draw on a specific case study as well as examples from the literature to show that although the processes of interaction differ, the resulting dynamic floodplain patchwork is a common feature of rivers with logjams. In addition, we contend that the presence of logjams is an important factor in the evolution and maintenance of multiple channel patterns in both montane and lowland river environments. These observations have important implications for the definition of reference targets for river restoration.The specific results of this research show:1)The presence of a range of types of multiple channel network dissecting the floodplains of low order channels that are strongly associated with the presence of logjams.2)The relatively rapid formation of floodplain channels following logjam formation.3)The dynamic nature of logjams within headwater channels on both seasonal and annual timescales that lead to a highly dynamic habitat mosaic on the floodplain surface.4)An increased frequency of overbank flooding and high rates of floodplain sediment accumulation upstream of logjams and along floodplain channel networks that create the complex topography observed in the case study forested floodplains.

Wood is an important element in many river systems, interacting with channel and floodplain geomorphology, hydrology and ecology. Restoration practices are increasingly re-introducing wood into streams and researchers have started to study the geomorphic and ecological effects of re-introducing wood into rivers. However, little research has attempted to quantify the impacts of river restoration (including the addition of wood jams) on wood retention. Based on tracing dowels to simulate small wood (ranging in length from 0·184 to 1·06 m and diameter from 0·006 to 0·035 m) in three study reaches before and after restoration, this study provides a detailed representation of the influence of restoration on small-wood transport and the relative importance of different trapping sites within a low-order meandering stream in the New Forest, UK. The research specifically addresses the following questions. (i) Does restoration reduce transport of small wood? (ii) Does restoration increase the frequency and type of small-wood trapping sites? (iii) Do wood jams trap more small wood than other trapping sites? (iv) Do shorter pieces of wood travel further than long pieces? The study has demonstrated that (i) different types of restoration have different effects on the frequency and type of small-wood trapping mechanisms, and hence also on small-wood transport; (ii) wood jams were the most effective structures for trapping small wood in this environment; (iii) shorter pieces of wood travelled further than long pieces. Channel–floodplain interactions were also found to be important, allowing the floodplain to function as a trapping site. Copyright © 2007 John Wiley & Sons, Ltd.