Recent advances quantifying the large wood dynamics in river basins: New methods and remaining challenges

Abstract

Large wood is an important physical component of woodland rivers and significantly influences river morphology. It is also a key component of stream ecosystems. However, large wood is also a source of risk for human activities as it may damage infrastructure, block river channels, and induce flooding. Therefore, the analysis and quantification of large wood and its mobility are crucial for understanding and managing wood in rivers. As the amount of large-wood-related studies by researchers, river managers, and stakeholders increases, documentation of commonly used and newly available techniques and their effectiveness has also become increasingly relevant as well. Important data and knowledge have been obtained from the application of very different approaches and have generated a significant body of valuable information representative of different environments. This review brings a comprehensive qualitative and quantitative summary of recent advances regarding the different processes involved in large wood dynamics in fluvial systems including wood budgeting and wood mechanics. First, some key definitions and concepts are introduced. Second, advances in quantifying large wood dynamics are reviewed; in particular, how measurements and modeling can be combined to integrate our understanding of how large wood moves through and is retained within river systems. Throughout, we present a quantitative and integrated meta-analysis compiled from different studies and geographical regions. Finally, we conclude by highlighting areas of particular research importance and their likely future trajectories, and we consider a particularly underresearched area so as to stress the future challenges for large wood research.

Large wood distribution, mobility, and recruitment in an inter‐dam river reach: A comparison with geomorphic process on the Garrison Reach of the Missouri River pre and post the historical 2011 flood

“…Figure 9. This study is notable due to the length and magnitude of the flood, something not shared by the other LW transport studies to date (Ruiz-Villanueva et al, 2016a). The figure demonstrates the two orders of magnitude increase in LW in the Lake Oahe slackwater and the likely majority source of LW 30 to 100 km upstream.…”

“…LW accumulation and dynamics are important for river management and science for a number of reasons including as productive habitat for aquatic organisms, an influence on channel dynamics and island formation, navigation and recreational risks, and as a nutrient exchange substrate (Ruiz-Villanueva et al, 2016a). LW accumulation and dynamics are important for river management and science for a number of reasons including as productive habitat for aquatic organisms, an influence on channel dynamics and island formation, navigation and recreational risks, and as a nutrient exchange substrate (Ruiz-Villanueva et al, 2016a).…”

Brief communication: The curious case of the large wood-laden flow event in the Pocuro stream (Chile)

“…3). To put this value into perspective, the volume of large wood measured within the channel after the event accounts for only 0.3 m 3 hectare −1 of sur- veyed channel area (mean log length and diameter of 1.53 and 0.08 m, respectively), which is well below other values available in the literature for basins of comparable size (see Ruiz-Villanueva et al, 2016). All evidence thus suggests that this was an extreme high-magnitude event, and that virtually all transported logs were recruited from upstream reaches or mass wasting processes at the basin scale, making the estimation of large-wood transport from in-channel large-wood deposition very difficult in these conditions.…”

“…WLF and CWT) and assuming that a third of the cross section was occupied by water, the estimated volume of transported wood is around 3680 m 3 . This volume is remarkably high, provided that in a recent review, Ruiz-Villanueva et al (2016) reported that large wood exported from basins > 100 km 2 generally ranges from 500 to 4000 m 3 (Fig. 3).…”

River logjams cause frequent large-scale forest die-off events in southwestern Amazonia

“…Logjams are also an important component of river ecosystems, as they influence the transfer of solutes, mineral sediment, and organic material within the river channel system and between the river and the floodplain (Coe et al, 2009;Gurnell et al, 2002;Jochner et al, 2015;Wohl and Beckman, 2014). Despite the fact that logjams can have a dramatic impact on fluvial dynamics and fluvial-floodplain exchanges, their systematic study is relatively recent and has mostly been carried out in temperate zones (Dixon, 2016;Ruiz-Villanueva et al, 2016;Wohl, 2017Wohl, , 2013. Very few studies have looked at the wood-river interactions in the neotropics, and these have mostly focused on headwater rivers Wohl, 2011, 2010;Iroumé et al, 2015;Wohl et al, 2012).…”