Landform Dynamics Research Articles

Analysis of spatio-temporal development of mining landforms using aerial photographs: Case study from the Ostrava–Karviná mining district

Abstract The anthropogenic relief transformations of the mining landscape are characterised by high dynamics of changes over time that can be effectively mapped on a large scale using aerial images. The Karviná part of the Ostrava-Karviná mining district, which stands for significant hard coal mining area in the Czech Republic, has been selected to analyse the spatio-temporal development of anthropogenic landforms. Anthropogenic landforms were visually identified from the aerial images from 1947, 1966, 1971, 1985, 1994, 2009, and 2018. Specific anthropogenic landforms were analysed along with their spatio-temporal changes based on obtained vector data. The total extent and number of anthropogenic landforms increased the most during the periods 1947–1966 and 1971–1985. The same anthropogenic landforms occurred on circa 24 hectares in the entire period 1947–2018. The most anthropogenic landforms remained preserved in the last observed period 2009–2018. The multi-temporal analysis of aerial photographs and overlay operations in GIS enabled to map the age of specific landforms and to identify changed or unchanged anthropogenic landforms. This method is suitable for the study of landform dynamics at mining sites and is particularly relevant for the planning challenges in post-mining reclamation.

Mapping surface sediment characteristics in enclosed shallow‐marine environments using spatially balanced designs and the random forest algorithm

AbstractMapping the sedimentary character of the seafloor in large water‐filled basins is fundamental for understanding landform dynamics to inform research, management, intervention and conservation actions. Seabed mapping methods have undergone considerable development in the last two decades, including the uptake of machine learning approaches for sediment size prediction and classification. However, predictions of surficial sediment characteristics are often hindered by the availability of ground truthing data, their arrangement in space and the modelling approach chosen. Spatially informed sampling designs provide an opportunity to significantly improve the accuracy and uncertainty of predicted sediment distributions. In this study, we apply a machine learning algorithm to predict sediment distributions across Port Phillip Bay, a large (1930 km2) structurally controlled estuary on the southeast coast of Victoria, Australia. Surface sediment samples (n = 252) were collected using a spatially balanced design, ensuring that sampling effort was spread evenly within the embayment with increased sampling intensity placed in more heterogeneous areas. Surficial textural metrics were modelled using the random forest algorithm with bathymetric and hydrodynamic predictor variables. Models highlighted trends in sediment grain size, sorting and composition consistent with predicted wave‐ and current‐induced sediment mobilisation. Model predictions were accurate (normalised‐root mean squared error [NRMSE]: 0.14–0.16); however, standard error was not homogeneous across the study area. Uncertainty maps highlighted areas where additional sampling effort may be needed, including areas where transitional bathymetry impacted surficial sediment character and areas of anthropogenic modifications to the seabed. This study shows the benefits of undertaking spatially informed sample design, block cross‐validation during model fitting and quantifying spatial uncertainty in predictive maps to accurately quantify the fundamental boundary conditions of sediment size. The results of this study are intended to inform local coastal management, including beach renourishment activities. However, approaches outlined are applicable to any study where the seafloor grain size is a fundamental variable in understanding landscape change.

Contemporary research in coastal dunes and aeolian processes

AbstractCoastal dunes are found along the sandy coasts of oceans, seas, and large lakes all around the world. They are dynamic landforms that evolve along complex morphological and biological continua in response to a range on controls linked to climate, sea level, sediment movement, vegetation cover, and land use. By collating research across the full spectrum of processes shaping different types and sizes of dunes and smaller aeolian bedforms, special issues can aid researchers to identify new research directions and methods emerging from the discipline. This editorial summarizes the 25 contributions to the special issue Coastal dunes: links between aeolian processes and landform dynamics. We grouped the contributions into four broad themes: (1) long‐term dune evolution, (2) short‐term aeolian transport, (3) research methods, and (4) coastal dune management. Contributions to the special issue demonstrate that research interest in coastal dunes, and particularly the impacts of human interventions on dunes, continues to grow. It also shows how aeolian research on coastal dunes covers a range of temporal and spatial scales, from ripple dynamics and instantaneous airflow‐transport processes to dune field evolution with rising sea levels and large‐scale dune stage shifts. We highlight potential avenues for future research including vegetation roughness characteristics and their effect on wind flow and sediment transport, the challenges of upscaling short‐ and small‐scale results to larger and longer spatiotemporal scales, and the study of both natural and managed dune landscapes.

Nature-based solutions for coastal resilience in South Africa

ABSTRACT Coastlines globally are sensitive to the effects of sea-level rise, increased coastal storminess and changes in coastal sediment supply and sediment dynamics in the Anthropocene. Coastlines are also influenced by land use change, urbanization and development of built infrastructure. These changes can affect the dynamics of coastal landforms, weaken coastal resilience and make coasts more sensitive to climate hazards. This study critically examines the properties of coastlines that contribute to coastal biophysical resilience in South Africa, highlighting their relativerates of change and dynamic behaviour in response to physical and human forcing factors. Coastal landforms can be considered as ‘green infrastructure’ that can buffer the effects of climate change as well as providing ecosystem and environmental services in their own right. Viewing coastal landforms as green infrastructure provides a ‘nature-based solution’ to mitigate against climate change impacts that can work with – not against – the natural geomorphic, sedimentary and ecological processes of coastlines. Coastal landforms can also contribute to socioecological resilience, where they provide environmental and ecosystem services. The green infrastructure approach to coastal resilience has not been well developed in South Africa but is more effective in supporting coastal sustainable development.

The Strategies of Sustainable Watershed Management at Bedog Sub-Watershed, Special Region of Yogyakarta

A watershed plays significant roles for maintaining the balance of ecosystem, particularly on the fluvial landform dynamics. Bedog Sub-Watershed as a part of Progo Watershed flows across 11 sub-districts from Sleman and Bantul Regency. This sub-watershed indicates rural-urban characteristics and multi-aspects problems, such as the loss of croplands, a massive land-use changes into built-up area, and the decrease of environmental carrying capacity. On the purposes of preventing the negative aftermaths, this research aimed to create the strategies of sustainable environmental management in case of Bedog Sub-Watershed. This research used secondary data from regional planning products, PODES data, and the relevant literature. Primary data was acquired from in-depth interview with BPDASHL Serayu-Opak-Progo and agricultural-related government agency to gain governmental perspective of watershed management. This research used qualitative descriptive technique to analyse the result of interview. Livelihood assets were calculated by scoring index. The SWOT and DPSIR analysis were conducted to create the relevant strategies implying physical, social-economy, and regional development perspectives in the post-COVID-19 pandemic. The strengthening of government’s institutional aspects was the key to the management followed by necessary comprehensive study in Bedog Sub-Watershed management.

Does large dam removal restore downstream riparian vegetation diversity? Testing predictions on the Elwha River, Washington, USA.

Large dams and their removal can profoundly affect riparian ecosystems by altering flow and sediment regimes, hydrochory, and landform dynamics, yet few studies have documented these effects on downstream plant communities. Ecological theory and empirical results suggest that by altering disturbance regimes, reducing hydrochory, and shifting communities to later successional stages, dams reduce downstream plant diversity. Dam removal could reverse these processes, but the release of large volumes of sediment could have unexpected, transient effects. Two large dams were removed on the Elwha River in Washington State, USA, from 2011 to 2014, representing an unprecedented opportunity to study large dam removal effects on riparian plant communities. Our research objectives were to determine: (1) whether the Elwha River dams were associated with lower downstream plant diversity and altered species composition across riparian landforms pre-dam removal, and (2) whether dam removal has begun to restore downstream diversity and composition. To address these objectives, we compared plant species richness and community composition in river segments above, below, and between the two dams. Plant communities were sampled twice before (2005 and 2010) and four times after (2013, 2014, 2016, and 2017) the start of dam removal, with 2013 and 2014 sampled while the upstream dam removal was ongoing. Prior to dam removal, native species richness was 41% lower below dams compared with the upstream segment; 6 years after dam removal began, it increased ~31% between the dams, whereas nonnative species richness and cover were not apparently affected by dams or their removal. Deposition caused by large volumes of released reservoir sediment had mixed effects on native species richness (increased on floodplains, decreased elsewhere) in the lowest river segment. Plant community composition was also different downstream from dams compared with the upstream reference, and has changed in downstream floodplains and bars since dam removal. In the long term, we expect that diversity will continue to increase in downstream river segments. Our results provide evidence that (1) large dams reduce downstream native plant diversity, (2) dam removal may restore it, and (3) given the natural dynamics of riparian vegetation, long-term, multiyear before-and-after monitoring is essential for understanding dam removal effects.

Dynamic river basins and hypsometric analyses: implications to land management and prioritization in Bohol, Central Philippines

ABSTRACT The study presented a method of characterizing landform dynamics that integrates a divide stability metric and hypsometric analysis. Chi (χ) - a proxy for steady-state river channel elevation - indicated a drainage divide stability. Simultaneously, the hypsometric analysis provided information on a basin's geologic development stage and erosion proneness. The study used a 30 m SRTM digital elevation data, the DivideTool/TopoToolbox of MATLAB, and the SWAT model. The tool computed χ values following the stream network, enabled the selection of divide sections, extracted channel head's χ values, determined divide stability by predicting migration direction for unstable divides, and produced histograms of χ values for each divide section. Equal χ values at the channel heads of opposing river networks indicated a stable divide. In contrast, a difference in χ values suggested an unstable divide and a potential to migrate from low χ values towards the divide's high χ values side. The study proposed the mean χ difference (χmd ) metric to indicate the degree of divide mobility. Meanwhile, the SWAT model defined the basins and subbasins and set the hypsometric analysis parameters. Each subbasin's hypsometric integral (HI) was used to create a continuous surface of HI values. The combination of χmd and HI analysis revealed nine subbasins with highly mobile divides and high erosional areas, identifying them as high-priority conservation zones. River basin characterization can utilize the new approach to target areas for location-specific land and water conservation measures and other developmental goals.

Mechanisms of land degradation and their environmental implications in a middle‐latitude desert area of China

AbstractThe movement of aeolian materials and dynamics of dune landforms are results of the transportation and accumulation of sandy sediments under the influence of climate, in which the processes that gave birth to sand dune formations are complex as the arid area has experienced different periods of humidity and aridity. These dynamics are still not well understood at present, especially at the inter‐decadal time scale. Based on a comprehensive analysis of geomorphological, sedimentological, geochemical, and ecohydrological data, this study discussed the dynamical changes of different dune landforms during the past half‐century and their formation mechanism in the Hexi Corridor, northern China. The results show that on the inter‐annual and inter‐decadal scales, the crescent‐shaped dunes move the fastest among different dune types. Dunes in Minqin move the fastest (at 6.2 ± 0.5 m yr−1) and dunes in Dunhuang move the slowest (at 0.8 ± 0.2 m yr−1). The dune sands are mainly medium sand (21.7%–57.4%) and fine sand (23.2%–53.0%) with an average grain size of 0.07 ± 0.01 mm ~0.24 ± 0.06 mm, similar to the world's average particle size of sand dunes. Annual precipitation and spring precipitation, annual average wind speed, and number of annual strong wind days are the main factors affecting the dynamic changes of dunes in the Corridor, indicating a major influence of climatic factors. STC (sufficient transport capacity) is evidenced for both the western and eastern Hexi Corridor, however, SSS (sufficient sand supply) and SA (sand availability) are the favourable factor for dune formation in the east part but is the limiting factor for the west. In the past half‐century, although the vulnerability of land degradation is a function of climate change, geomorphological processes, and anthropogenic pressure in the Hexi Corridor, water resource limitations have been more important.

Sedimentary processes and palaeoenvironments from La Combette sequence (southeastern France): climatic insights on the Last Interglacial/Glacial transition

During the Last Interglacial-Early Glacial transition (MIS5-MIS4; ~73 ka), substantial hydroclimatic changes affected morphogenetic processes, landform dynamics, and ecosystem variability over the Mediterranean sub-alpine valleys. This transition is mainly preserved in the northern Mediterranean region in continuous marine, lacustrine, and peat bog archives. To understand better local-to-regional hydro-sedimentary processes, their climatic significance, and their direct impact on prehistoric settlements, this manuscript reinvestigates a known continental sedimentary record with revised methods. The Middle Palaeolithic site of La Combette in the western Provence region (southeastern France) presents a thick sedimentary key sequence for studying environmental changes from the MIS5 to the MIS3. A review of previous studies with the integration of new micromorphological, sedimentological, physicochemical, malacological, and luminescence ages allows us to characterize the sedimentary processes and environmental patterns during this major climatic transition. Alternating warm and cold conditions and shifting vegetation patterns reflect the strong environmental instability of the end of the Last Interglacial Period. The emergence of a steppe-like ecology dominated by cryo-turbated loess deposition marks the beginning of the Early Würmian Glacial period (MIS4-MIS3; ~73 ka to ~50 ka), contemporaneous with the last Neanderthal occupation at La Combette rock shelter. Comparisons with regional palaeoclimatic data allow us to detail local climatic settings and provide evidence of divergences with larger-scale quantitative reconstructions during a period of significant environmental and socio-cultural shifts.

Quantification of permafrost creep provides kinematic evidence for classifying a puzzling periglacial landform

AbstractMechanical processes operating on the slope surface or at depth control the dynamics of alpine landforms and hold critical information of their geomorphological characteristics, yet they often lack systematic quantification and in‐depth interpretation. This study aims to address a long‐standing issue concerning geomorphological classification from a kinematic perspective. A group of periglacial landforms consisting of several lobes were discovered in the East Kunlun Mountains of China 30 years ago but were ambiguously classified as rock glaciers and later as gelifluction deposits. Here, we use satellite Interferometric Synthetic Aperture Radar to quantitatively characterize the spatial and temporal changes of the surface movement of these landforms. We observe that: (1) its 17 lobes show a pattern of landform‐scale and uniform surface movement, especially during May to October; (2) the lobes move at a spatial mean downslope velocity of 10 to 60 cm/yr and a maximum velocity as high as 100 cm/yr in summer; (3) the landforms are nearly inactive from winter to late spring. Based on these observations, we postulate that the movement of the lobes are driven by deep‐seated permafrost creep which typically occurs in rock glaciers. The debris of Lobe No.4 is composed of both boulders and pebbles supported by fine‐grained matrix generated from the in situ weathering process. It develops a talus‐like oversteepened front around 40° and a convex transverse profile perpendicular to the creep direction, which are also characteristic features of a rock glacier. Piecing these observations together, we identify Lobe No.4 as a debris‐mantled‐slope‐connected rock glacier, with the gelifluction process occurring on the surface as small‐scale and discrete events. © 2020 John Wiley & Sons, Ltd.

Signatures of late Quaternary land-sea interactions and landform dynamics along southern Kerala coast, SW India

The Kerala coast displays a spectrum of varied geomorphic features that are evolved as a function of Late Quaternary land-sea interaction. The southern Kerala coast, south of Achankovil Shear Zone (ASZ) has been characterised by cliffed coast with entrenched estuarine basins, pocket beaches, promontories, older and younger strand plains, etc., that are evolved as a result of the transgressive-regressive phases to which the coast has been subjected during the late Quaternary Period. In spite of having varied geomorphic features, lacuna in comprehending the evolutionary phases of the coastal landform features is the primary impediment that bolstered us to unravel the Late Quaternary land-sea interactions and landform changes of the coast between Thottapally and Vizhinjam. Moreover, the last two centuries are known to have been witnessing many natural as well as human induced environmental perturbations in the area.The present study attempts to reconstruct the late Quaternary landform dynamics based on the satellite data while the last century changes were extracted from the Digital Shoreline Analysis System (DSAS). The evidences based on geomorphic variations suggest that the present study area hosts two distinct paleo-coastlines – 1) coincides with the eastern boundary of the older strand plains (accreted during Late Pleistocene) and, 2) marks the boundary between older and younger strand plains (accreted during Early–Middle Holocene). A sector-wise analysis reveals that the northern half of the study area is characterised by many coast perpendicular estuarine basins with well-developed Bay Head Deltas in its fluvial end, and Flood Tide Islands near the estuarine mouth. On the contrary, the southern half is characterised by pocket beaches and coast parallel backwater bodies developed during the regressive phases of the sea. A high-resolution study of the shoreline changes during the period, 1920–2018 reveals that the younger strandlines are vulnerable to severe coastal erosion and shoreline retreat at many places compared to coastal accretion. The study stresses the imminent need for continuous monitoring and implementation of site-specific mitigation measures for the conservation and management of this coast known for its outstanding natural beauty and strategic beach placer deposits.

Virtual element method for the numerical simulation of long-term dynamics of transitional environments

The prediction of long-term dynamics of transitional environments, e.g., lagoon evolution, salt-marsh growth or river delta progradation, is an important issue to estimate the potential impacts of different scenarios on such vulnerable intertidal morphologies. The numerical simulation of the combined accretion and consolidation, i.e., the two main processes driving the dynamics of these environments, however, suffers from a significant geometric non-linearity, which may result in a pronounced grid distortion using standard grid-based discretization methods. The present work describes a novel numerical approach, based on the Virtual Element Method (VEM), for the long-term simulation of the vertical dynamics of transitional landforms. The VEM is a grid-based variational technique for the numerical discretization of Partial Differential Equations (PDEs) allowing for the use of very irregular meshes consisting of a free combination of different polyhedral elements. The model solves the groundwater flow equation, coupled to a geomechanical module based on Terzaghi's principle, in a large-deformation setting, taking into account both the geometric and the material non-linearity. The use of the VEM allows for a great flexibility in the element generation and management, avoiding the numerical issues connected with the adoption of strongly distorted meshes. The numerical model is developed, implemented and tested in real-world examples, showing an interesting potential for addressing complex environmental situations.

INDICATIVE ANALYSIS OF THE DYNAMICS OF GEOMORPHOLOGICAL PROCESSES IN THE STUDY OF THE TRANSFORMATION OF THE NORTHERN BLACK SEA COASTAL SOIL

The article analyzes the most expressive indicative features of exogenous geomorphologic processes in assessing their role in the transformation of soil cover. Each of the above-mentioned geomorphologic processes is capable of creating in the process of its activity a material mass that can subsequently become a parent species of a certain variety of soil, and the direction and intensity of processes are the basis for assessing the rates of mechanical degradation of soils. It has been established that the spectrum of modern exogenous processes is significant and multifactorial in terms of its manifestation and development, which leads to the need for their recognition and evaluation in the formation, use and transformation of soil cover. Characterized how the massive masses formed by certain geomorphologic processes in the investigated area, in one way or another, influence the formation of varieties of soil differentiation of the region. An attempt has been made to establish the existing, expected and assume the probable impact of a certain geomorphologic process on soil characteristics, which indicates the prospect of ecological and geomorphologic evaluation of the formation, distribution, operation and transformation of the soil cover of the Northern Black Sea coast. This attempt to explain the correlation of the dynamics of forms of relief and the state of soil cover follows from the new methodical approach of taking into account when assessing the correlation of the main properties of the terrain topography. It has been established that modern exogenous geomorphologic processes, due to their activities of denudation, transit and accumulative nature, carry out the constant production of material masses, are an important factor in the formation of soils, taking them into account gives a much more detailed picture of the distribution of differences in the soil cover of the Northern Black Sea region. In the studied territory, the spectrum of modern exogenous processes is significant (deluvial, gravitational complex, linear erosion, fluvial accumulation, karst, subsidence and gleying, suffusion, abrasion, estuary accumulation and multifactorial in manifestation and development, which leads to the need for their recognition and evaluation in the formation, use and transformation of the soil cover. There are morphological, genetic, age and dynamic signs that the material masses that are formed by certain geomorphological processes in the studied area, one way or another, influence the formation of varieties of soil differences in the region. Key words: modern exogenous geomorphologic processes, soil cover; indicative signs; the Northern Black Sea region; correlation of the dynamics of landforms and the state of the soil cover.

Species composition and plant traits: Characterization of the biogeomorphological succession within contrasting river corridors

AbstractPlant communities and dynamics can be characterized according to species composition or plant traits. Here, we used species composition and plant traits to compare their effectiveness in discriminating the biogeomorphological (involving reciprocal feedbacks between physical and biological processes) and ecological (mainly biologically driven) phases of the fluvial biogeomorphological succession (FBS) model. The comparison was done between two French rivers, the largely unchannelized lower Allier and the channelized middle Garonne. One reach representative of each river section was selected for the study. Within each river reach, we chose two contrasted study sites in terms of channel and floodplain dynamics: a reference site (least altered channel and floodplain dynamics) and an altered site (laterally stabilized by riprap and constrained). In the four study sites, we sampled vegetation in 402 plots of 4 m2. The 512 species identified in the plots were characterized in terms of plant traits (20) from a literature review. When comparing reaches in unconstrained ordinations and permutational multivariate analyses of variance, both species composition and plant traits led to a similar identification of the biogeomorphological and the ecological successional trajectories. Nevertheless, the trait approach was less influenced by local and regional bioclimatic, hydrogeomorphological, and anthropogenic settings and thus produced a more comprehensive and general classification of the biogeomorphological and ecological phases of the FBS model. A lower than expected contrast between the four sites was found, because neither species composition nor plant traits could entirely characterize distinct successional trajectories occurring in our reference or altered sites. Furthermore, our results contributed to a better understanding of the multiple successional trajectories that can occur in midlatitude river corridors. It also showed that relating plant traits to their effects on fluvial landform dynamics remains a core challenge in explaining succession including feedback mechanisms between hydrology, morphodynamics, and vegetation dynamics.

Geomorphology of Proglacial Systems: Landform and Sediment Dynamics in Recently Deglaciated Alpine Landscapes

Geomorphology of Proglacial Systems: Landform and Sediment Dynamics in Recently Deglaciated Alpine Landscapes

Block stream characteristics in Southern Carpathians (Romania)

Block streams, as common features in the Southern Carpathians, are essential for understanding the evolution of alpine environments. Despite their widespread occurrence, they have frequently been omitted from previous inventories of periglacial landforms and from the general understanding of landscape development. This study evaluated the environmental controls on spatial distribution and dimensions of 2056 block streams for a better understanding of their evolution and climatic significance. Different lithology classes and topographic characteristics were assessed using standard least-square linear regression and one-way analysis of variance (ANOVA). The majority of the block streams belong to the linear morphological type, but six other types of morphologies were found (e.g. sinuous, curved, and braided). Bivariate and multivariate statistical analysis revealed a high density of landforms on southern slopes (59%), granite terrains (47%), and above 1750 m. Large features occur mainly on southern slopes and in areas with granites. Landform dimensions and spatial distribution are influenced to a certain degree by lithology, slope aspect, and elevation, making it difficult to identify a dominant factor. Block streams developed extensively at the end of the Pleistocene under permafrost conditions. Today, these features suggest inactivity, but during the cool episodes of the Holocene (e.g. Little Ice Age - LIA), the formation of block streams above 2100 m was re-initiated. Future absolute dating and monitoring of landform dynamics will support these findings.

Morphological Dynamics of the Jamuna River in Kazipur Subdistrict

This study identifies and evaluates the morphologically changing trend and process–response mechanisms of Jamuna River. The study considers the bank erosion, bank-line shifting, rate of erosion, accretion, sedimentation, course changing directions, changes in river width, fluvial landform dynamics, and floodplain features. The lower Brahmaputra–Jamuna River (named Jamuna River) at Kazipur subdistrict, Sirajganj district in Bangladesh are the study area. Multispectral Landsat satellite imageries of dry seasons were used for time series analyses of time periods (1972–2016) to interpret the chronological changes of morphology. The outcomes obtained from the analyse, support the historical westward channel shifting of the river, alluvial material properties, explicate fluvial processes, discharge anabranch instability, erosion, and morphological responses.

Niche construction within riparian corridors. Part I: Exploring biogeomorphic feedback windows of three pioneer riparian species (Allier River, France)

Within riparian corridors, biotic-abiotic feedback mechanisms occur between woody vegetation strongly influenced by hydrogeomorphic constraints (e.g., sediment transport and deposition, shear stress, hydrological variability), fluvial landforms, and morphodynamics, which in turn are modulated by the established vegetation. During field investigations in spring 2015, we studied 16 alluvial bars (e.g., point and lateral bars) within the dynamic riparian corridor of the Allier River (France) to assess the aptitude of three pioneer riparian Salicaceae species (Populus nigra L., Salix purpurea L., and Salix alba L.) to establish and act as ecosystem engineers by trapping sediment and constructing fluvial landforms. Our aim is to empirically identify the preferential establishment area (EA; i.e., the local areas where species become established) and the preferential biogeomorphic feedback window (BFW; i.e., where and to what extent the species and geomorphology interact) of these three species on alluvial bars within a 20-km-long river reach. Our results show that the EA and BFW of all three species vary significantly along the longitudinal profile, i.e., upstream-downstream exposure on the alluvial bars, as well as transversally, i.e., the main hydrological connectivity gradient from the river channel toward the floodplain. In the present-day context of the Allier River, P. nigra is the most abundant species, appearing to act as the main engineer species affecting landform dynamics at the bar scale; S. purpurea is established and acts as an ecosystem engineer at locations on alluvial bars that are most exposed to hydrosedimentary flow dynamics, while S. alba is established on the bar tail close to secondary channels and affects the geomorphology in mixed patches along with P. nigra. Our study highlights the role of functional trait diversity of riparian engineer species in controlling the extent of fluvial landform construction along geomorphic gradients within riparian corridors exposed to frequent hydrogeomorphic disturbances.

Latest Holocene depositional history of the southern Venice Lagoon, Italy

Analyzing the signatures of landscape changes in the stratigraphic record is crucial to refine our knowledge of tidal landform dynamics and represents a first step toward the development of predictive morphodynamic models. The southern Venice Lagoon (Italy) is particularly suited to analyze modifications in the depositional environment and, consequently, in the sedimentary record because of the remarkable changes that occurred in the last centuries. We collected 25 cores along a NE–SW linear transect about 5 km long cutting through salt marshes, tidal flats, and subtidal platforms. High-resolution sedimentological analyses defined the spatial arrangement of four deposits along the transect (palustrine, salt marsh, lag, and tidal-flat/subtidal-platform deposits), whose cores were dated through radiocarbon, 210Pb, and 137Cs geochronological analyses. The study succession testifies an evolution from a palustrine freshwater environment to a lagoonal environment over the last 2000 years. The palustrine peat progressively evolved into salt marshes in the 14th century. Salt-marsh aggradation is characterized by different accretion rates over time and occurred in parallel with the decrease in the salt-marsh extent and tidal-flat expansion. Where salt-marsh deposits were locally flooded and impacted by wind waves, a lag deposit developed. As a consequence of the progressive water deepening, organic-rich mud accumulated above the lag. The results, as well as providing the first accretion model for the latest Holocene succession in the southern Venice Lagoon, highlight that the disappearance of salt marshes in this area has to be ascribed to the lateral erosion of their margins, rather than to their progressive drowning.

Biogeomorphology: diverse, integrative and useful

AbstractBiogeomorphology is an umbrella term given to a highly‐active research area within geomorphology that focusses on the many and varied interactions and feedbacks between organisms and the physical Earth. In the last 25 years this interest has developed and diversified to include the direct and indirect influences of microorganisms, plants, animals and humans on earth surface processes and landform dynamics, and the roles of geomorphology in ecological functioning, resilience and evolution. This Commentary introduces a virtual special issue of 16 research papers and three ‘State of Science’ pieces, illustrating the diversity of the field, its continued theoretical and conceptual progression, and the applied relevance of biogeomorphological science in tackling environmental problems. Collectively, these papers demonstrate the merits of – and opportunities for – biogeomorphology as an inherently integrative science in understanding and managing the complexity of living landscapes. Copyright © 2016 John Wiley & Sons, Ltd.