Wood and sediment storage and dynamics in river corridors

Abstract

Large wood along rivers influences entrainment, transport, and storage of mineral sediment and particulate organic matter. We review how wood alters sediment dynamics and explore patterns among volumes of in-stream wood, sediment storage, and residual pools for dispersed pieces of wood, logjams, and beaver dams. We hypothesized that: volume of sediment per unit area of channel stored in association with wood is inversely proportional to drainage area; the form of sediment storage changes downstream; sediment storage correlates with wood load; the residual volume of pools created in association with wood correlates inversely with drainage area; and volume of sediment stored behind beaver dams correlates with pond area. Lack of data from larger drainage areas limits tests of these hypotheses, but the analyses suggest that sediment volume correlates positively with drainage area and wood volume. The form of sediment storage in relation to wood appears to change downstream, with wedges of sediment upstream from jammed steps most prevalent in small, steep channels and more dispersed sediment storage in lower gradient channels. Pool volume correlates positively with wood volume and negatively with channel gradient. Sediment volume correlates well with beaver pond area.More abundant in-stream wood and beaver populations present historically equated to greater sediment storage within river corridors and greater residual pool volume. One implication of these changes is that protecting and re-introducing wood and beavers can be used to restore rivers. This review of the existing literature on wood and sediment dynamics highlights the lack of studies on larger rivers.

Spatial and temporal patterns of sediment storage over 45 years in Carnation Creek, BC, a previously glaciated mountain catchment

“…; Gomi et al. ; Wohl and Scott, ), logjams are associated with zones of elevated sediment storage. While logjams do not appear to be the dominant mechanisms through which sediment is stored in Carnation Creek, the clear association between storage and logjams in sections SAV and SAVIII lends strength to the argument that logjams are at least locally significant agents of sediment storage in forested systems, increasing sediment trapping efficiency along channels (see Eaton et al.…”

Beavers affect carbon biogeochemistry: both short‐term and long‐term processes are involved

“…). Beavers also cut and transport wood to the water from unflooded shores (Wohl & Scott ). Colonies remove on average 8 Mg (megagram = 10 6 g) of trees (4 Mg of C, Liu & Westman ) per year from the browsing zone around their ponds.…”

“…The persistence of beaver‐induced sediments varies depending on hydrological, geomorphical, and environmental factors. Often, part of the fine sediment is quickly transported out of the former beaver pond after dam breaching (Levine & Meyer , Wohl & Scott ), but considerable long‐term sedimentation may still take place (Polvi & Wohl , Wohl et al. ).…”

Reintroduced large wood modifies fine sediment transport and storage in a lowland river channel

“…Increased sediment storage within the LW signals that the dispersion processes lead to retention of sediment within the LW jam, while the maintenance of channel depth in patches adjacent to the LW reflects more efficient transport of sediment. Increases in spatial variability of sediment transport and storage caused by the reintroduced LW in this artificially over‐widened lowland river channel reflect previous findings from studies of naturally occurring LW in higher energy environments (Nakamura and Swanson, ; Montgomery et al , ; Wohl and Scott, ) and, by creating a more diverse array of physical habitats for aquatic organisms, could help to address legislative requirements like the EU Water Framework Directive (European Union, ).…”