• Large wood in rivers has been a subject of study since the early 20th century, but the field has expanded greatly since the 1980s.
• Roles and regimes of streamflow, sediment, and large wood are now recognized as the essential interactive components of fluvial geomorphic systems.
• Research has made important advances through intensive, sustained investigations focused on critical issues, such as environmental hazards in mountain landscapes, protection and restoration of river ecosystems, and roles in global carbon dynamics.

We developed a riparian forest structure model that predicts shifts in tree size and density as a function of floodplain age on dynamic alluvial rivers. The model uses a Weibull distribution with time-dependent parameters and was calibrated with field inventory data from the middle Sacramento River (California, USA). We generated predictions of large wood inputs based on historical bank retreat rates. Other applications include modelling the response of riparian forest biomass and habitat to different river management and restoration actions.

We investigate the influence of glacial history on hillslope-channel coupling, channel geometry, and morphology in two forested mountain streams in coastal British Columbia. Glaciation of the catchments introduced variable patterns of hillslope–channel coupling, resulting in variability of hillslope sediment and wood input, channel morphology, and channel geometry. We evaluate observed channel geometry against models predicting width, depth, and slope, and results of statistically analyzing model residuals indicate that substantial variability can be explained by slope failure and logjam variables.

Floodplain large wood loads for unmanagedriver corridors reach maximum values in the temperate latitudes. This reflects the combined effects of forest primary productivity and rates of wood decay.

In confined valleys, falling trees usually suspend the channel (A), providing less function for streams than logs inside the channel (B). After nine years, wood decayed, became shorter, but 46.5% of them were still suspending the channel. Wood size and channel geomorphology were the main factors that explained changes in suspended wood. The transition from suspended to non-suspended can be a long-term process that can increase wood residence time and reduce wood in-stream functions in confined valleys.

In the last 13 years, huge fluctuations in wood load were detected from 2006 (592 logs), to 2009 (324 logs), and until 2019 (1329 logs). This fact demonstrated that after two subsequent wildfires (2002 and 2015) the recruitment is already going on, even if there are not so many surficial instabilities and mass movement directly connected to the channel network. Positive correlations were detected between the preferential sub-reaches of deposition and both, mean slope and a newly introduced roughness index.

Floating wood flux is monitored by video on two sites on the Ain and Is?re Rivers, France. The interriver comparison provides a better understanding of the link between wood regime and flood characteristics and some recommendations for installing and calibrating equipment and applying this monitoring technique on different rivers.

We collected evidences from 28 home movies from 7 countries to define and characterize wood-laden flows. We propose a novel classification that encompasses a range from clear water to hypercongested wood debris flows, depending on the composition of sediment, wood and water. And we attempted to simulate this type of flows, discussing the application of different models.

Large wood (LW) load was investigated in the 36 river corridor segments within the inter-dam reach of the Dyje River in the non-flood period 2009–2018 following three major floods. Tagging of LW in 36 river corridor segments together with documenting LW floated to the downstream dam revealed the spatiotemporal pattern of LW recruitment, transport and depletion. A mean export of 7.7 LW pieces per month was recorded in the 2013–2018 period lacking discharges exceeding bankfull stage.

We analysed the large wood characteristics and reach-scale variables in a Mediterranean intermittent river (Evrotas, Greece). Our results indicated high downstream variation in large wood volumes in the fluvial corridor. In-channel and floodplain large wood retention was primarily driven by the hydrological regime of the studied reaches (i.e., perennial or non-perennial) with higher volumes of LW observed in perennial sections. The width of the riparian corridor was an important predictor of large wood storage at the reach scale.

• Land management and tree species exert a major influence on wood inventory and budget in streams.
• Important wood load fluctuations occur at annual and decadal intervals (see figure for wood load along the Vuelta de Zorra segment).
• Harvest legacies must be considered when interpreting large wood dynamics.
• Long-term monitoring has paramount value in robustly assessing wood load fluctuations at a decadal time scale, irrespective of possible short-term changes.

Map of difference in channel-bed elevation between 2009 and 2014. Reach identifiers are at left for each reach and wood load (in m3/ha) is at right. The maximum aggradation was 2.8 m and the maximum erosion was 4.3 m.

Bar colonization by vegetation and subsequent island formation is a key bio-geomorphological process in fluvial landscape evolution. We investigate morphological and ecological evolution of river islands over single floods to decades, focussing on islands initiated by deposited trees that sprout to form vegetated patches.

Debris flows in heavily forested southeast Alaska runout significantly less than debris flows elsewhere around the world. Jamming of logs and root wads at the flow front is the most likely cause of reduced mobility. Vegetation therefore strongly affects hazard severity and the routing of sediment and carbon through the landscape.

This study discusses the reproducibility of a numerical model for simulating the morphodynamics involved in the transport of large pieces of wood in a braided river.

Porosity of wood jams in streams has implications for estimating wood volumes and impacts of jams on geomorphic and ecological processes. We compare methods to estimate jam porosity and wood volume using field data in North America. Accuracy of porosity estimates is still unknown, but visual estimates, although likely underestimated, remain the most time-efficient method. We provide a framework that uses wood piece sorting and structural organization with modeled jam porosity values and methodological recommendations for future studies.

Overall, instream logs do not increase bank erosion rate, but individual logs can increase or decrease bank erosion rate by altering the near-bank hydraulics. A hydraulically isolated log (S2) can increase near-bank velocity and bank erosion rate, but hydraulic interactions between logs (between S2 and M3) can reduce this increase, or even decrease the near-bank velocity. Depending on the near-bank velocity change caused by logs, instream logs (C5) can weaken or reinforce the recirculation flow associated with a curved bank.

Logjam with electrical resistivity sensors deployed across the channel upstream (at left).

• Coarse particulate organic matter (CPOM) transport was measured in a third-order stream in southern Chile.• Peak discharge during each sampling interval did not explain the transported CPOM and we proposed an exponential rating curve using the mean discharge.• Annual CPOM yields were within the range observed in streams in the United States and Brazil but much lower than values observed in European streams.• Two contrasting mechanisms characterize the dynamics of CPOM in rivers: a steady-state input and transport or a fully episodic mode.