ICG2022-16

Riparian areas are important ecosystems that need to be restored and protected in the Anthropocene era. In Quebec, Canada, conservation laws and management strategies focus on ecological services provided by riparian communities, such as erosion and flood control, carbon sequestration, and pollutants filtration. However, there is a need to incorporate fluvial biogeomophological approaches to improve our understanding of those systems. Biogeomorphology explores both the impacts of flood regime and disturbances on plant structure and composition and the role of plant communities in altering hydrosedimentary processes. Approaches anchored in biogeomorphology have proven to be efficient to understand interactions and feedbacks between fluvial dynamics and plant ecology in many contrasted environments, from temperate to arid regions and from small streams to large rivers. However, those approaches have never been applied to rivers disturbed by ice dynamics. Ice jams and mechanical breakups are known to disturb fluvial systems, both geomorphologically and ecologically. Moving ice during breakups has the potential to severely erode banks and transport sediment, thus destroying riparian habitat and disturbing plant succession dynamics. Feedback dynamics between plants and rivers are thus obviously affected by ice disturbances regime. There is a need to understand how fluvial biogeomorphic systems respond to such disturbances to assess better management strategies and improve prevision models in a context of climatic change. In this poster, we expose a research project aiming at conceptualizing how ice disturbances regime controls the biogeomorphic interactions in two rivers located in eastern Quebec, Canada. To do so, analyses will be held in three distinct spatiotemporal scales: 1) decennial biogeomorphological trajectories, 2) plant community structure and composition on distinct fluvial landforms and 3) functional traits of ice-disturbed indicator species.

How to cite: Prugne, M., Buffin-Bélanger, T., Boivin, M., and Corenblit, D.: Biogeomorphic interactions in ice-driven fluvial hydrosystems, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-216, https://doi.org/10.5194/icg2022-216, 2022.

Coastal Plain rivers represent sites of extraordinary ecological and biogeochemical importance for many reasons. One such reason is that large wood (LW), which serves to regulate sediment and biogeochemical processes as well as enhance geomorphic complexity, is readily transported and deposited in such systems.  However, most research on LW dynamics has taken place in low order, montane river systems and thus little is known of LW dynamics and the interactions of LW and channel morphology in higher order, coastal plain river systems. One of the challenges to understanding wood dynamics in such systems is the ability to locate and quantify subaqueous wood. This research, funded by the National Science Foundation, presents a case study of the Lumber River, an Atlantic coastal plain blackwater river located in North Carolina, USA in which we investigate wood dynamics. Specifically, we use a SONAR-based approach to mapping subaqueous wood in association with channel bedform. Using a canoe/kayak mounted SONAR unit we develop high resolution images of bed morphology and sub-aqueous wood, and report on the results of remote sensing algorithms that aim to extract wood geometry/volume, which is then assessed within the context of the bed morphology. This will help us gain a better understanding of the relationships between channel morphology and wood transport/deposition in low-gradient, high order river channels, and provide more accurate inputs to wood/carbon transport models.

How to cite: Martin, D., Praskievicz, S., Platt, J., and Stephens, S.: Using SONAR to Investigate Relationships Between Fluvial Wood and Channel Bedform in a Low Gradient, Coastal Plain River, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-192, https://doi.org/10.5194/icg2022-192, 2022.

Shallow landslides are instability events that lead to mass wasting of soil and vegetation in sloping areas and are commonly triggered by intense rainfall. Since vegetation is an important factor influencing the occurrence of rainfall-triggered shallow landslides and reduces the likelihood of landslides through different hydromechanical mechanisms, conducting in-depth research in this field for disaster risk management is meaningful. Investigating vegetation recovery processes after shallow landslides can provide significant insights for improving future disaster habitation works. However, vegetation recovery processes after shallow landslides and their influencing multivariate factors are not well known. Therefore, the objective of this study is to clarify the effects of geology and topography on vegetation recovery after shallow landslides in two research areas, the Shobara district, Hiroshima Prefecture, Japan, and the Obara district, Aichi Prefecture, Japan. Image analysis of historical aerial photographs was used to extract landslide-affected areas. Temporal changes in vegetation-condition indices were accessed from satellite imagery. GIS tools were used to extract topographic and geological indices. The relationships among those factors were quantified using a multivariate analysis of variance. Time series analysis was conducted by using the seasonal autoregressive integrated moving average. The change in time series, climate data, topographic, and geological characteristics were incorporated into a framework for mapping and modeling vegetation recovery. The results have quantitatively revealed both similarities and differences in vegetation recovery between the two areas in relation to geomorphological and geological conditions.

How to cite: Zhong, C. and Oguchi, T.: Effects of topography and geology on vegetation recovery after shallow landslides, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-396, https://doi.org/10.5194/icg2022-396, 2022.

Insects are the largest and most diverse group of living organisms on Earth, playing a critical but underestimated role as agents of geomorphic change. Burrowing insects create micro-scale landforms such as subterranean tunnels and surface mounds and, by this way, have a substantial impact on hydrology, soil erosion and sediment transfer at a wider landscape scale. On another side, geomorphic environments and landform heterogeneity strongly influence insect distribution and diversity. The aim of this presentation is to explore the reciprocal links between geomorphology – the study of landforms – and entomology – the study of insects –, beyond the well-known and classical considerations about the role of social ants and termites as geomorphic agents and ecosystem engineers. Five types of insect-landform relationships are examined in this scope: (1) insect ethology and geomorphic processes, (2) insect ecology and geomorphic environment, (3) insect diversity and landform heterogeneity, (4) insect decline/invasion and Anthropocene geomorphology, and (5) insect conservation and landform management. The evidence of reciprocal links between insects and landforms lays out the contours of an Insect Zoogeomorphology – or Entomogeomorphology – as a potential subfield of biogeomorphology to be developed further. Such zoogeomorphological studies should contribute to a better understanding of the importance of insects in Earth surface processes and landforms, with many useful applications in environmental management projects and strategies (e.g., restoration projects of grasslands and wetlands, translocation strategies for the conservation of species and associated biogenic landforms…).

How to cite: Bétard, F.: Insect zoogeomorphology: Exploring the links between geomorphology and entomology, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-6, https://doi.org/10.5194/icg2022-6, 2022.

In eastern Canada, the retreat of the Laurentide Ice Sheet over the last ~12,000 years, corresponding to the Holocene – the present interglacial period - has left immense quantities of surficial sediments over the entire territory. Today, these sediments still represent in a very variable way in time and space, an abundant source of fine and coarse sediments for fluvial and coastal systems and, to a lesser extent, for mass movements. Although the geomorphological dynamics of landscapes have been studied for a long time, biotic factors and particularly animals have not yet been deeply studied in terms of their interactions with the abiotic world. The present contribution sheds new light on the geomorphological impact of the trophic relationship between red fox (Vulpes vulpes) and bank swallow (Riparia riparia). Indeed, the predator-prey relationship between these two species and their behaviours accentuate the erosion of sandy cliffs where swallows nest, because by red fox makes foraging pits to reach the eggs and young swallows. Even if our data based on a four-year survey indicate low rates of cliff recession related to biotic effects compared to the impact of extreme hydrological events, it remains that they contribute to the sediment budget at short and long term. In that regard, we have documented over the last four years from an original point of view the common relationship predator-prey with a geomorphic perspective and propose to discuss this topic with significant field dataset.

How to cite: Germain, D., Luciano, J., and MIlot, J.-F.: The predator-prey relationship from a zoogeomorphic perspective: An example with red fox (Vulpes vulpes) and bank swallow (Riparia riparia), Canada, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-541, https://doi.org/10.5194/icg2022-541, 2022.

Moles (small insectivorous mammals of the family Talpidae) are widespread across the Northern Hemisphere, with their ranges covering Europe, Asia, and North America. The presence of these subterranean mammals is easily detected through the mounds, or molehills, which they construct as surface bioproducts of tunnel systems excavated underground. These bioconstructions created by moles indicate they may play geomorphologically important roles in sediment systems. The bioturbation of soils by moles has also been shown to be ecologically important as they mix nutrients and aerate soils, suggesting that their role in local sediment systems may be intrinsically linked to ecosystem functioning. However, compared to other fossorial animals (species which dig, e.g. ants, rabbits, badgers etc.) the impact of moles as direct and indirect biogeomorphic agents and their role as ecosystem engineers is poorly understood. For instance, relatively little is known about the impact of moles on microtopography, surface runoff and erosion rates, vegetation cover, and soil properties.

By examining molehills created by the European mole (Talpa europaea) in Oxfordshire, UK, we provide a quantitative assessment of how these landforms evolve over time and space. Following the mapping of molehills at selected sites and regular monitoring over a 6-month period, this study estimates the rate of sediment movement caused by mole activity. We also examine what happens to molehill morphology post-construction, as well as the characteristics of soil bioturbated by moles vs. non-bioturbated soil and the potential impact of molehills on local biodiversity.

How to cite: Baxter, T., Woor, S., and Viles, H.: The geomorphic work of the European mole and its role as an ecosystem engineer. A case study from Oxfordshire, southern England., 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-203, https://doi.org/10.5194/icg2022-203, 2022.

The UK supports 15% of the world’s blanket peat cover but much of this vital resource is significantly degraded. In damaged peatlands runoff is quickly evacuated from hillslopes across bare peat surfaces and through erosional gullies, exacerbating downstream flooding. The restoration of damaged UK peatlands is a major conservation concern, and landscape-scale restoration by revegetation and damming of gullies is extensive in areas of upland Britain. There is increasing evidence that the restoration techniques can significantly slow the flow of water in addition to providing other ecosystem service benefits. More recently, focus has shifted from stabilising eroding surfaces to the reintroducing Sphagnum moss as part of multi-benefit restoration initiatives.

This paper reports the results of long-term post-restoration monitoring on the Kinder Plateau in the southern Pennines of the U.K. Two sites were revegetated using lime-seed-fertiliser-mulch in 2011 and one of the sites was also gully blocked in 2012 and had a further phase of restoration in the form of intensive Sphagnum planting in 2015. A third unrestored control site was also monitored. We present post-intervention biogeomorphological changes spanning 10 years, showing the long-term trajectories of vegetation cover, runoff, sediment production, and water table.

The trajectories of recovery for different functions differ in form and rate. At both treatment sites, vegetation cover increases rapidly then slows as full cover is approached. Sediment production is quickly reduced to levels comparable to intact peatlands within two years and bare peat cover becomes negligible after ~7 years. Key runoff metrics (e.g. peak discharge and lag time) show similar immediate step changes as a result of increased surface roughness from the rapid vegetation expansion, followed by more gradual improvements as species richness develops through time.  The addition of gully blocking enhances the impact of re-vegetation alone, amplifying the step change, but there are no further benefits apparent in the longer-term trajectory. The introduction of Sphagnum provides further roughness, leading to marked increases in lag times and attenuation of runoff. There is also preliminary evidence that the Sphagnum inhibits surface drying, providing resilience to future climatic and anthropogenic stressors.

This study provides the first evidence that the reintroduction of Sphagnum in degraded headwater peatlands can provide additional Natural Flood Management benefits compared to standard restoration techniques aimed at stabilising eroding surfaces. We also show that water table recovery is not at odds with flow attenuation. We also note the importance of control assessing the impact of restoration interventions and the need for investment in longer-term (>10 year) monitoring to better understand the recovery of restored peatlands.

How to cite: Shuttleworth, E., Evans, M., Tim, A., Martin, K., Adam, J., Edokpa, D., Joe Lake, R., David, M., Salim, G., Joseph, H., Michael, P., and Tom, S.: A ten-year trajectory of change in a restored blanket peatland: implications for natural flood management, 10th International Conference on Geomorphology, Coimbra, Portugal, 12–16 Sep 2022, ICG2022-200, https://doi.org/10.5194/icg2022-200, 2022.