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Preface: Multiscale Feedbacks in Ecogeomorphology
... Fluvial systems are formed by a wide range of elements with multiple non-linear interactions on different spatial and temporal scales (Knighton, 1998;Rice et al., 2010a;Wheaton et al., 2011;Stoffel et al., 2013). The geomorphological elements of a river system (Newson, 2002;Blue and Brierley, 2015) are key influences on the biological component that often motivates fluvial assessment and restoration (Frissell et al., 1986;Palmer et al., 2010). ...
... The LTUs are delimited on the same level as river basins (50-500 km 2 ) (Montgomery and Buffington, 1998). However, LTUs differ from river basins in that they identify sectors in which different geomorphological processes influence ecological processes (Montgomery, 1996;Brierley et al., 2006;Wheaton et al., 2011). While river basins provide a logical basis for resource management, their spatial limits do not generally coincide with the underlying lithological framework. ...
... The importance of geomorphology for the ecological understanding of a river (Kondolf, 1995;Clarke et al., 2003;Reinhardt et al., 2010;Rice et al., 2010a,b;Wheaton et al., 2011;Bizzi and Lerner, 2012) justifies the addition of a descriptor (LTU) that organizes territory according to geomorphological criteria within the characterization rules of the WFD. In recent years there have been a number of works of ecological state evaluations that incorporate geomorphology (Elosegi et al., 2010;Wyzga and Zawiejska, 2012;Speed et al., 2016). ...
River classification is one of the recommendations of the European Water Framework Directive 2000/60/EC,
which establishes that classifications should be carried out according to different variables hierarchically organized from a smaller to a larger scale. We suggest incorporating into the Directive’s hierarchical system a
geoecological unit (lithotopo unit) that discriminates rivers with similar geomorphological features and ecological funtionality. The lithotopo units are not an alternative to the Directive typology, they are a complement intended to improve it.
Our method is divided into two stages, the first focused on the development of LTUs and the second on their
validation. We applied the concept of lithotopo units to a 30,000 km2 region in the NW of the Iberian Peninsula
(Spain) using a Geographic Information System and field work. Seven kinds of lithotopo units were identified for
the study area, each with its own geomorphological processes and dynamics, and, as a consequence, particular
associated habitats. Cartographic validation was done through the analysis of 122 sample sites distributed in
eight basins. Of the five validation variables originally employed, specific stream power and median grain size
are the two that yielded the best results. Each kind of lithotopo unit displays a range of values of specific stream power and median grain size that is internally homogeneous but different from that of the other units. The methodology thus produced, which can be applied to other regions, is transparent, objective and quantitative.
... Bu yaklaşım, jeomorfolojik özellikler ve canlılar arasındaki etkileşimleri konu alan çalışmalarla ilgilenen yeni bir jeomorfoloji branşıdır. İlk örneklerinin 1800'lü yılların sonunda görülen bu bilim dalına ait araştırmalar, 1990'lı yıllarda popüler bir karakter kazanmıştır (Wheaton vd., 2011: 265). Genellikle biyojeomorfoloji ile eş anlamlı olarak tanımlanan (Hupp vd., 1995: ii) ekojeomorfolojinin ana teması; ekolojik, jeomorfolojik ve hidrografik sistemler arasındaki ilişkidir (Naylor vd., 2002: 4). ...
... Genellikle biyojeomorfoloji ile eş anlamlı olarak tanımlanan (Hupp vd., 1995: ii) ekojeomorfolojinin ana teması; ekolojik, jeomorfolojik ve hidrografik sistemler arasındaki ilişkidir (Naylor vd., 2002: 4). Bu ilişkinin net bir şekilde aydınlatılması ve kavramsal çerçevede ortaya konulması için ilgili sistemler arasındaki yapısal ve işlevsel bağlantının incelenmesi gerekir (Wheaton vd., 2011: 268). Söz konusu inceleme daha çok erozyon veya sedimantasyon süreçleri konusundaki uygulamaları kapsamaktadır (Mondal, 2014: 1). ...
... Şekil 1. Ekojeomorfolojik araştırmalarının temel unsurları (Wheaton vd., 2011: 266'dan düzenlenerek) ...
This study aims to examine the eco-geomorphological features of the Ganos (Işıklar) Mount. This aim was constructed within the framework of the cycle of geo (geomorphology-landform systems, slope, and aspect), eco (ecology-habitats), and hydro (hydrography-water erosion), which are the key elements of eco-geomorphological research. Various materials obtained from different sources were used, and two different methods were employed in the study. Erosion analysis was made through GIS (Geographic Information Systems) based RUSLE (Revised Universal Soil Loss Equation) while the relationship between erosion and factors influential on eco-geomorphology was analyzed based on frequency ratios. GIS techniques were used in analysis and preparation of thematic maps. The eco-geomorphological susceptibility of the study area was determined and mapped through spatial analysis of the factors influential on eco-geomorphological features according to erosion risk classes. It was seen that the average susceptibility of the study area corresponds to high susceptibility class (35.60%). Since the distribution patterns of susceptibility values in the mountainous area represent the general character of vegetation formations, there is a spread from the central to the periphery. The areas where susceptibility values are lower include moist forests while the areas with higher susceptibility values contain dry forests or maquis. In terms of main landforms, these areas correspond to mountain (DI) and plateau (DII and DIII) areas respectively. This distribution points out anthropogenic influence intensity, too. Susceptibility is higher in the areas where such influence is more intense and vice versa. The research results revealed the existence of a complex relationship between anthropogenic influence and eco-geomorphology in the study area. Handling this relationship eco-geomorphologically proved to be effective in showing the intensity of the effect of erosive activities on ecosystem. Therefore, GIS techniques may be considered effective for similar works and future plans. Similar research should be carried out in other ecologically important areas, too. In this sense, great responsibilities fall to geographers.
... However, Erle C. Ellis (2015) used anthroecology to couple 'ecology with society across evolutionary time through integrative scientific frameworks including anthroecosystems, anthrosequences, anthrobiogeography, anthroecological guilds and anthroecological succession' (Ellis 2015). Source: Partly adapted from Wheaton et al. (2011) 20 2.1 A hillslope as a system, showing storages (waste mantle), inputs (e.g. wind deposition and debris production), outputs (e.g. ...
... However, Erle C. Ellis (2015) used anthroecology to couple 'ecology with society across evolutionary time through integrative scientific frameworks including anthroecosystems, anthrosequences, anthrobiogeography, anthroecological guilds and anthroecological succession' (Ellis 2015). Source: Partly adapted from Wheaton et al. (2011) ...
... The growth of fluvial geomorphology as applied science can also be deduced from the significant technological advances made in geomorphological analysis and monitoring (Piégay et al., 2020;Wheaton et al., 2011), with a level of detail unthinkable just two decades ago (Kondolf and Piégay, 2016). The essential geomorphological knowledge acquired for a range of complex river typologies is fundamental for effective river management (Thorndycraft et al., 2008;Downs and Thorne, 1996;Fryirs and Brierley, 2016). ...
... We have found multiple ways that the 'geo' aspect of multidisciplinary concepts is diluted. One is that terms such as ecohydraulics, hydroecology or ecohydrology do not emphasize geomorphology, but they are often used by environmental agencies to implicitly include the geomorphological perspective (Wheaton et al., 2011). A second is a tendency, following the WFD technocratic language diffusion, to simplify the word "hydrogeomorphology" by removing the root 'geo'. ...
Is geomorphology at the forefront of river management? The aims of this article are to explore potential answers to this question in terms of role, barriers, motivation and prospects for river management in the Anthropocene Era. We justify and execute our analysis, first through the growing interest in applied geomorphology and its role to improve river ecology and river policy design; second, by interviewing 24 specialists (researchers (i.e., biologists, ecologists, geomorphologists), engineers, river managers, planners) from different countries. We detected three barriers (academic, management and social) that prevent geomorphology from being more involved in river policy. We then propose three principles for living with rivers, considering geomorphology one of the key factors: (i) working across disciplinary frontiers, (ii) promoting integrated approaches, and (iii) improving fluvial education. Our conclusions look to rivers as natural and dynamic systems where geomorphological knowledge can improve the skills of engineers, ecologists and embrace a transdisciplinary approach. The new riverscape that we propose for the Anthropocene Era must be conceived using negotiation and discussion between an interconnected network of actors, regulators, scientists (sometimes), and natural and cultural values, where management objectives are raised and designed.
... Fluvial geomorphology studies the interactions between river channel forms and processes in a range of space and time scales (Charlton 2008). Geomorphology is key for understanding the interaction of biophysical processes (Urban and Daniels 2006;Rice et al. 2010;Wheaton et al. 2011;Stoffel et al. 2013), and therefore for understanding fluvial ecology. A wide range of classifications exist, developed under hydrological, chemical and biological criteria. ...
... The second principle alludes to the self-classification fluvial concept (Stølum 1996;Sapozhnikov and Foufoula-Georgiou 1999;Hooke 2007;Fryirs 2015). The processes and shapes of the natural river are in balance with the fluvial system, and this derives in the generation of a specific ecogeomorphological environment (Wheaton et al. 2011;Stoffel et al. 2013). Whatever morphology, for example, riffle-pool, is generated in specific SSP and MGS conditions (Montgomery and Buffington 1997), which additionally involves a hydraulic geometry adjusted to those terms of balance (e.g., width:depth ratio). ...
The classification of rivers based on geomorphological criteria played, in the past, a secondary role for management decision making, although in the last years they have experienced a shift from the scientific field to that of the technical. Currently, managers require the most simplified form of classifications in order to use them in plans and planning projects, management and restoration. On the one hand, this means that classifications should be directed toward simplifying the diversity of fluvial environments in a number of manageable types, and on the other hand, to apply to each geomorphic type a management model. In this study, we have developed a method of “Geomorphic Classification of Rivers” according to specific stream power variables and median grain size. The new method is dynamic (ability to readjust and gain robustness with the incorporation of new data) and predictive. We obtained six types directly from the method, although we added a seventh type (bedrock rivers) for its special singularity. Each geomorphic type presents concrete values of specific stream power and median grain size, which additionally involves a hydraulic geometry adjusted to terms of balance. The change from a geomorphic type to another would reflect a geomorphologic imbalance in the form of greater power and sediment size. Our results have been compared with six commonly used classifications (e.g., Rosgen Classification System or River Styles Framework). “Geomorphic Classification of Rivers” stands as a flexible tool that allows the development of a “personalized” geomorphic classification for rivers of the same geomorphological province. Through the temporary revision of various sites that act as control points, we can learn, should the case arise, the intensity and geomorphic change of the site. “Geomorphic Classification of Rivers” acts as an alert system for any geomorphologic disturbance. Its simple application and interpretation facilitate the implementation in the administrative environment, or its attachment to other commonly used classifications.
... Much more recently, a wide array of papers, volumes, and symposia has attempted to squarely integrate the fast emerging, now increasingly distinct field of biogeomorphology as termed by Viles (1988). Ecogeomorphology is essentially synonymous with biogeomorphology and perhaps is better reflective of the field (Hupp et al., 1995;Wheaton et al., 2011). The editors of the present volume have had a relatively long appreciation for the body of work relating biota and geomorphic form and process (Butler, 1995;Hupp et al., 1995) and hope our efforts here continue to underscore the scientific value of ecogeomorphology. ...
... Ecogeomorphology (or biogeomorphology) as a symposium topic began in 1990 with the British Geomorphic Research Group (Thornes, 1990). The following two decades have experienced a tremendous increase in the number of ecogeomorphic publications including symposia proceedings (Hupp et al., 1995;Bennett and Simon, 2004;Hession et al., 2010;Wheaton et al., 2011). This increase in ecogeomorphic publications was documented by Hession et al. (2010) where they searched in the Web of Science using the keywords 'vegetation and geomorphology ' and found 7 publications between 1977-86, 95 between 1987-96, 425 between 1997-2006, and 186 in just the three years 2007-09. ...
... In this article, we propose an alternative and more comprehensive view of stream evolution as an ecological-or more precisely, ecogeomorphic-process (sensu Wheaton et al. 2011). We provide a conceptual model for incised stream evolution that describes stream succession as a process dependent on the interaction of living organisms with hydrologic and sediment dynamics. ...
... Therefore, where biogenic features are present, they largely control the extent of trench widening in a classic ecogeomorphic feedback loop (Wheaton et al. 2011). Where these features are absent, the extent of widening is controlled by erosivity of the bank walls relative to stream power, and incision trench width can be substantially greater (Simon and Rinaldi 2006). ...
Biogenic features such as beaver dams, large wood, and live vegetation are essential to the maintenance of complex stream ecosystems, but these features are largely absent from models of how streams change over time. Many streams have incised because of changing climate or land-use practices. Because incised streams provide limited benefits to biota, they are a common focus of restoration efforts. Contemporary models of long-term change in streams are focused primarily on physical characteristics, and most restoration efforts are also focused on manipulating physical rather than ecological processes. We present an alternative view, that stream restoration is an ecosystem process, and suggest that the recovery of incised streams is largely dependent on the interaction of biogenic structures with physical fluvial processes. In particular, we propose that live vegetation and beaver dams or beaver dam analogues can substantially accelerate the recovery of incised streams and can help create and maintain complex fluvial ecosystems.
... Geomorphology, hydrology, and climate are essential components determining macroscale variation in VCE processes 9 . As a result, each VCE has a set of environmental conditions that control the type and rate of sediment supply, origin of organic carbon (autochthonous vs. allochthonous), organic matter diagenesis, and C storage in vegetation and soil pools 10,11 . ...
Vegetated coastal ecosystems (mangroves, seagrasses, and saltmarshes, often called Blue Carbon ecosystems) store large carbon stocks. However, their regional carbon inventories, sequestration rates, and potential as natural climate change mitigation strategies are poorly constrained. Here, we systematically review organic carbon storage and accumulation rates in vegetated coastal ecosystems across the Central and Southwestern Atlantic, extending from Guyana (08.28°N) to Argentina (55.14°S). We estimate that 0.4 Pg organic carbon is stored in the region, which is approximately 2-5% of global carbon stores in coastal vegetated systems, and that they accumulate 0.5 to 3.9 Tg carbon annually. By ecosystem type, mangroves have the largest areal extent and contribute 70-80% of annual organic carbon accumulation, with Brazil hosting roughly 95% of mangrove stocks. Our findings suggest that organic carbon accumulation in the region is equivalent to 0.7 to 13% of global rates in vegetated coastal ecosystems, indicating the importance of conserving these ecosystems as a nature-based approach for mitigating and adapting to climate change.
... In this thesis, I regard these two terms to be synonym and use biogeomorphology. Nevertheless, some authors point to slight differences in the foci of eco-and biogeomorphology (see e.g.Wheaton et al., 2011). ...
In the arid and semi-arid climate of Central Asia, the endorheic rivers and their ecosystems play a crucial role as regional hotspots of biodiversity and for the provision of ecosystem services for local people. The Naryn River in Kyrgyzstan as the object of interest of this thesis is one of these rivers. On a flow length of more than 600 km, it is still in a widely natural condition making it an interesting study object in a world where most large rivers are distorted by anthropogenic activities. Despite this relevance, no comprehensive scientific studies are available about the Naryn River except water resource related research. In particular, large scale information about the structure and functioning of the Naryn River system from an interdisciplinary perspective is missing. Against this background, this thesis aims to fill the research gap and deliver up-to-date information about the Naryn River corridor with a special focus on biogeomorphology, i.e. the dynamic interaction between hydromorphology and vegetation. First, this thesis delivers the necessary background information about the Naryn River corridor including a general overview, an assessment of ecosystem services, a field based overview of the structure of the riparian ecosystems and an in-depth analysis of hydrology. Basing upon this background, remote sensing methods adapted to the data-scarce environment of Central Asia are used to derive various parameters of the structure of the Naryn River on the scale from reaches to the entire river corridor. Then, the large scale biogeomorphological structures and dynamics are assessed based on dense time series of multispectral satellite imagery. From the results, it becomes obvious that the structure of the corridor of the Naryn River is heterogeneous and mainly controlled by geological contraints. Only in a laterally unconfined segment, dynamic braided river reaches can form. In these reaches, the majority of biogeomorphological interactions take place. The outcome of this thesis is on the one hand the provision of large scale and up-to-date information about the structure and functioning of the Naryn River corridor as a basis for further research or decision making. On the other hand, this thesis presents innovative remote sensing methods for large scale characterization of river corridors. In particular, an approach for the characterization of dynamic processes of biogeomorphological interactions on a large scale is developed based on time series analysis of satellite imagery. This approach can complement biogeomorphological research on smaller spatial scales by delivering spatially and temporally continuous information for entire river corridors. This has the potential to obtain new insights of the processes and emergence of structure in river systems across multiple scales.
... Biogeomorphology (or ecogeomorphology) focuses on the interface between the earth and biological sciences, which considers the two-way feedbacks between ecological and geomorphic processes and how these processes influence ecosystems and landform evolution (Viles, 1988;Naylor et al., 2002;Wheaton et al., 2011). Although the term "biogeomorphology" was first coined by Viles (1988), early ecologists "recognised the need for the documentation of geomorphic form and process" (e.g., Cowles, 1899Cowles, , 1901Clements, 1916) to explain species distributions (Hupp et al., 1995). ...
Mangrove forests (Avicennia marina) occupy New Zealand's northern estuaries, which range in size from 1 to 750 km². Contrary to the global pattern of forest loss, areal expansion of New Zealand's mangrove forests has averaged 4% yr⁻¹ since the 1930s. These modern mangrove forests have colonized intertidal flats as they have progressively accreted above mean sea level (MSL), following catchment deforestation (mid–late 1800s) and soil erosion resulting in 10-fold increases in estuary sedimentation rates. The fate of these mangrove ecosystems under rising sea levels depends on maintaining intertidal sedimentary environments. Data from 18 estuaries show that potential mangrove habitat (i.e., intertidal area above MSL) is well predicted by an exponential relationship with the ratio of catchment annual sediment load to estuary tidal-prism volume (r² = 0.69, P < .001). Coastal embayments have the smallest areas of intertidal habitat above MSL due to limited fluvial sediment supply. Barrier-type estuaries have the largest intertidal areas above MSL and have also experienced the largest increases in mangrove forest habitat. A case study is presented from the Firth of Thames, where mangroves have colonized some 11 km² of rapidly accreting intertidal flat since the early 1960s. Seedling recruitment is largely governed by tidal and stochastic variations in water level and substrate disturbance by waves. Sediment delivery to the mangrove forest is controlled by spring-tide inundation coupled with onshore winds that resuspend intertidal muds. Surface-elevation gain is constrained by sediment desiccation and compaction during the summer. Simulations of future sea-level rise and sediment-supply scenarios indicate that intertidal habitats in small tidal creeks (0.1-km fetch [F]) and estuaries (1-km F) will maintain their elevation relative to MSL at relatively low sediment-supply rates. By contrast, intertidal flats in the largest estuaries (10-km F) will be vulnerable to inundation by rising seas. Sediment-supply rates twofold higher than historically will be required to sustain these larger systems. The potential for landward retreat of mangrove forests will be limited by storm-defence infrastructure.
... biogeomorphology, integrating concepts from ecology, evolutionary biology, engineering, geomorphology, geology and Quaternary science (e.g. Knox, 1972;Naylor, 2005;Wheaton et al., 2011;Larsen et al., 2018;Viles, 2019). Viles (2019) recognizes three key thematic areas, which represent geomorphological units, for which a brief review of the state of science is given below. ...
Biogeomorphology has been expanding as a discipline, due to increased recognition of the role that biology can play in geomorphic processes, as well as due to our increasing capacity to measure and quantify feedbacks between biological and geomorphological systems. Here, we provide an overview of the growth and status of biogeomorphology. This overview also provides the context for introducing this special issue on biogeomorphology, and specifically examines the thematic domains of biogeomorphological research, methods used, open questions and conundrums, problems encountered, future research directions, and practical applications in management and policy (e.g. Nature based solutions). We find that whilst biogeomorphological studies have a long history, there remain many new and surprising biogeomorphic processes and feedbacks that are only now being identified and quantified. Based on the current state of knowledge, we suggest that linking ecological and geomorphic processes across different spatio‐temporal scales emerges as the main research challenge in biogeomorphology, as well as the translation of biogeomorphic knowledge into management approaches to environmental systems. We recommend that future biogeomorphic studies should help to contextualise environmental feedbacks by including the spatio‐temporal scales relevant to the organism(s) under investigation, using knowledge of their ecology and size (or metabolic rate). Furthermore, in order to sufficiently understand the ‘engineering’ capacity of organisms, we recommend studying at least the time period bounded by two disturbance events, and recommend to also investigate the geomorphic work done during disturbance events, in order to put estimates of engineering capacity of biota into a wider perspective. Finally, the future seems bright, as increasingly inter‐disciplinary and longer‐term monitoring are coming to fruition, and we can expect important advances in process understanding across scales and better informed modelling efforts.
... Biogenic factors add complexity to incised channels and begin to reduce stream power with physical obstructions. The added roughness causes reduced stream power, stream flow deflection, bank erosion, and point bar deposition, synergistically driving the process of channel widening, aggradation and revegetation to rebuild anastomosing and ecologically resilient stream systems(Montgomery & Buffington 1997, Wheaton et al. 2011, Levine & Mayer 2013, Cluer & Thorne 2014. Reintroducing several biogenic factors in series may be a feasible approach to repairing the severe channel scouring occurring after large wildfires followed by significant precipitation events. ...
... Over evolutionary and geological timescales Cotterill and De Wit (2011) have proposed the term 'geoecodynamics'. Wheaton et al. (2011) provide a good review of the changing terminology. Within ecology, parallel developments have also occurred, with overlapping but rather broader concepts such as 'ecosystem engineering' becoming firmly rooted and widely utilised (Jones et al., 1994). ...
Since the 1970s there has been a considerable expansion in biogeomorphological research which considers the complex, two-way relationships between biological, ecological and geomorphological systems over a wide range of spatial and temporal scales. Advances have been made in theoretical, methodological, thematic and applied aspects of biogeomorphology. A review of key publications and symposia over the period illustrates growth in biogeomorphology with particular advances in quantitative understandings of biogeomorphic interactions, in interdisciplinary participation, and in theoretical framings. Theoretical advances have been influenced by the desire to answer four fundamental questions: How do ecological and geomorphological systems interact? Is there a geomorphological signature of life? How important is biodiversity to landscape evolution and vice versa? How have life and landscape co-evolved? A review of methodological advances in biogeomorphology confirms the continuing importance of field monitoring, and the increasingly tight collaboration between experimental and modelling-based research. Thematically, particularly strong progress has been made in disentangling the complex bidirectional biogeomorphic interactions in coastal sedimentary environments, and fluvial and riparian systems. It is increasingly obvious that variation in ecological traits leads to large differences in biogeomorphic impacts of different species in different circumstances. This poses challenges for applications of biogeomorphology to environmental management and conservation. Seven key topics emerge from this review and provide the basis for a biogeomorphological research agenda to usher in the next 50 yr of progress.
... An emergent property that identifies the large fluvial systems of the planet is the high environmental heterogeneity which is a consequence of the interaction of geomorphological, hydrological and biological organization levels (Thorp et al. 2006, Wheaton et al. 2011, besides the increasing influence of anthropogenic factors (Sitzia et al. 2016). This heterogeneity determines that their floodplains present a mosaic where landforms contrast in age and formation processes, and where plant com-munities of very variable diversity currently co-exist in similar hydro-sedimentological regimes (Kollmann et al. 1999, Neiff 2004, Latrubesse 2008, Hupp & Osterkamp 2013. ...
The high environmental heterogeneity of large fluvial systems is reflected by the coexistence of contrasting plant communities and landforms. The main objective of this study was to assess the forest diversity changes in islands of the Middle Paraná River (Argentina) in order to discuss an integrative question: how synchronized are the major changes in the features of islands and forests? Persistence age, elevation and flood regime of 11 main channel islands were determined. Variables related to the vascular plant community and the tree stand structure of forests were also measured in 400 m 2 plots. Islands were classified as young or old (YIs or OIs), according to their persistence age, which ranged from two to 108 years. Both island classes differed in their elevation but not in the proportion of low water phase. Only three out of nine tree species were dominant: Tessaria integrifolia and Croton urucurana (restricted to YIs and OIs, respectively), and Salix humboldtiana (distributed in both island classes). Alpha diversity was positively correlated with the age of the YIs and reach the highest value in the oldest island forest. Beta diversity was mainly due to processes of species replacement which differentiate floodplain forests. Gamma diversity reached 101 species, being the perennial herbs a clear majority. The stand structure and the complete floristic composition were significantly different between YIs and OIs, with three and seven indicator species of each island class, respectively. Considering integrative models of succession, our findings suggest that the biogeomorphic phase, recognised by the fluvial biogeomorphic model, prevailed in the whole range of island persistence ages. Therefore, it seems that the increase in forest diversity in a large river is restricted to spatial refugia defined by major hydrogeomorphic shifts.
... Along with microbial life and vegetation (biogeomorphology: Viles, 1988), animals can affect sediment fluxes and moderate landform development, a process regime referred to as zoogeomorphology (Butler, 1995;Hall and Lamont, 2003;Butler and Sawyer, 2012;Holtmeier, 2015). Intricate ecogeomorphological feedbacks can affect the responsible organism or wider community (Naiman et al., 2000;Wheaton et al., 2011;Beschta and Ripple, 2012), in which case the geomorphological effect is a form of ecosystem engineering (Jones et al., 1994;Moore, 2006;Wright and Jones, 2006;Jones, 2012). Zoogeomorphological contributions to ecosystem engineering are therefore part of the evolutionary process that entwines the biotic and abiotic elements of the Earth's surface in the co-development of life and landscape (Meysman et al., 2006;Corenblit et al., 2007;Steiger and Corenblit, 2012). ...
... Wave power, tidal and fluvial processes, along with regional climate, represent the main subsidiary energies of coastal zones, and the relative contribution of these environmental drivers produces conspicuous coastal environmental settings (CES), including deltas, estuaries, lagoons, composite deltas and lagoons, bedrock, and carbonate settings 3,4 (see Methods for a summary of these CES). Built on this ecogeomorphology framework 5 , the CES approach recognizes hydrology, geomorphology and climate as the main components of macroscale variation in coastal wetland ecological processes 3,4 . Hence, each coastal setting has a conspicuous environmental signature that controls both the type and rate of sediment supply to the coastline, nutrient load and limitation (for example, the nitrogen-to-phosphorus stoichiometric ratio), organic matter diagenesis, and, ultimately, carbon storage in vegetation (above-and below-ground biomass) and soil pools 1,3,4,6,7 (Supplementary Fig. 1). ...
Because mangroves store greater amounts of carbon (C) per area than any other terrestrial ecosystem, conservation of mangrove forests on a global scale represents a potentially meaningful strategy for mitigating atmospheric greenhouse‐gas (GHG) emissions. However, analyses of how coastal ecosystems influence the global C cycle also require the mapping of ecosystem area across the Earth's surface to estimate C storage and flux (movement) in order to compare how different ecosystem types may mitigate GHG enrichment in the atmosphere. In this paper, we propose a new framework based on diverse coastal morphology (that is, different coastal environmental settings resulting from how rivers, tides, waves, and climate have shaped coastal landforms) to explain global variations in mangrove C storage, using soil organic carbon (SOC) as a model to more accurately determine mangrove contributions to global C dynamics. We present, to the best of our knowledge, the first global mangrove area estimate occupying distinct coastal environmental settings, comparing the role of terrigenous and carbonate settings as global “blue carbon” hotspots. C storage in deltaic settings has been overestimated, while SOC stocks in carbonate settings have been underestimated by up to 50%. We encourage the scientific community, which has largely focused on blue carbon estimates, to incorporate coastal environmental settings into their evaluations of C stocks, to obtain more robust estimates of global C stocks.
... Wave power, tidal and fluvial processes, along with regional climate, represent the main subsidiary energies of coastal zones, and the relative contribution of these environmental drivers produces conspicuous coastal environmental settings (CES), including deltas, estuaries, lagoons, composite deltas and lagoons, bedrock, and carbonate settings 3,4 (see Methods for a summary of these CES). Built on this ecogeomorphology framework 5 , the CES approach recognizes hydrology, geomorphology and climate as the main components of macroscale variation in coastal wetland ecological processes 3,4 . Hence, each coastal setting has a conspicuous environmental signature that controls both the type and rate of sediment supply to the coastline, nutrient load and limitation (for example, the nitrogen-to-phosphorus stoichiometric ratio), organic matter diagenesis, and, ultimately, carbon storage in vegetation (above-and below-ground biomass) and soil pools 1,3,4,6,7 (Supplementary Fig. 1). ...
... Wave power, tidal and fluvial processes, along with regional climate, represent the main subsidiary energies of coastal zones, and the relative contribution of these environmental drivers produces conspicuous coastal environmental settings (CES), including deltas, estuaries, lagoons, composite deltas and lagoons, bedrock, and carbonate settings 3,4 (see Methods for a summary of these CES). Built on this ecogeomorphology framework 5 , the CES approach recognizes hydrology, geomorphology and climate as the main components of macroscale variation in coastal wetland ecological processes 3,4 . Hence, each coastal setting has a conspicuous environmental signature that controls both the type and rate of sediment supply to the coastline, nutrient load and limitation (for example, the nitrogen-to-phosphorus stoichiometric ratio), organic matter diagenesis, and, ultimately, carbon storage in vegetation (above-and below-ground biomass) and soil pools 1,3,4,6,7 (Supplementary Fig. 1). ...
Global-scale variation in mangrove ecosystem properties has been explained using a conceptual framework linking geomorphological processes to distinct coastal environmental settings (CES) for nearly 50 years. However, these assumptions have not been empirically tested at the global scale. Here, we show that CES account for global variability in mangrove soil C:N:P stoichiometry and soil organic carbon (SOC) stocks. Using this ecogeomorphology framework, we developed a global model that captures variation in mangrove SOC stocks compatible with distinct CES. We show that mangrove SOC stocks have been underestimated by up to 50% (a difference of roughly 200 Mg ha⁻¹) in carbonate settings and overestimated by up to 86% (around 400 Mg ha⁻¹) in deltaic coastlines. Moreover, we provide information for 57 nations that currently lack SOC data, enabling these and other countries to develop or evaluate their blue carbon inventories.
... The ecogeomorphological approach taken in this study (e.g. Murray et al. 2008;Wheaton et al. 2011) explicitly explores the co-relationships between land surface properties and selected biotic components. These relationships have been most commonly explored in deglaciating mountain landscapes where the land surface is unstable because of glacigenic slope relaxation, and where pioneer species are colonizing across virgin terrain (Caviezel et al. 2014;Klaar et al. 2015;Eichel et al. 2016;Tampucci et al. 2017). ...
In the Drakensberg Range of eastern Lesotho, periglacial sorted circles, stone-banked and turf-banked lobes, blockfields, block streams and wetland thúfur (earth hummocks) are present. These features are of varying ages (likely from Last Glacial Maximum to contemporary) and have been disturbed by soil formation and vegetation growth. This study uses a mixed methodology to investigate relationships between periglacial landforms, slope aspect and their associated ecosystems, and the relative age relationships of these components at Mafadi Peak on the Lesotho–South Africa border. A distinctive alpine flora, belonging to the Drakensberg Alpine Centre of the wider Afromontane phytochorion, is found in association with different periglacial landforms. Vegetation quadrat analysis shows that slope and aspect have no significant effect on vegetation cover, plant species abundance and bare ground cover. The most likely microscale relationships are with surface geomorphic features. The relative surface hardness and thus age of clasts within and outside of the stone/turf-banked lobes show that even within single landforms, variations in weathering exist, likely related to episodic and seasonal alpine cryoturbation. Major soil physical properties (grain size, organic and C/N content) and soil depth were measured. Weathering and soil development, influenced by climate, provide a substrate for a nutrient-deficient, sparse alpine flora and vegetation assemblage. The relationships between periglacial geomorphology and alpine ecosystems are not well understood from southern African high mountain regions, but are important with respect to ecosystem responses to ongoing climate change.
... Los sistemas fluviales se caracterizan por un funcionamiento muy complejo con múltiples variables interactuantes a diferentes escalas espaciales y temporales (Wheaton et al., 2011). Entre ellas, son especialmente relevantes los caudales líquidos y los caudales sólidos, que son las variables externas, que ejercen principalmente el control del sistema (Malavoi & Bravard, 2010). ...
Hydrological and geomorphological studies have increased in recent years indicating their importance to understand the functioning of river systems. In this research, the hydrogeomorphological quality of the Utcubamba River, located in the Amazon basin, was evaluated. By applying the Hydrogeomorphological Index (IHG) along its main watercourse the basin was divided into eight river sections. The results showed that the Utcubamba River is affected by significant anthropogenic impacts which modify the hydrogeomorphological conditions, with an increasing damage of them from its river source to his mouth. The quality of the riverbanks is most affected along the entire basin, mainly in the lower course due to extensive agriculture and livestock farms that are dominant in this part. Moreover, the IHG showed a complete adaptability to the conditions of the study area, in a different geographical area and far from the Iberian Peninsula.
... In recent years, much work has been done on feedbacks in "biogeomorphology" and/or "ecogeomorphology" (Fisher et al. 2007, Darby 2010, Hession et al. 2010, Reinhardt et al. 2010, Rice et al. 2010b, Wheaton et al. 2011, Schoelynck et al. 2012. ...
... In the last five years journal special issues have emerged that focus on particular aspects of biogeomorphology. These include ecogeomorphology (Wheaton et al., 2011), zoogeomorphology (Butler and Sawyer, 2012), vegetation and disturbance regimes (Stoffel et al., 2013), biopedturbation (Whitesides and Butler, 2015) and fluvial ecosystem engineering (Harvey and Bertoldi, 2015). With a few exceptions (e.g. ...
Biogeomorphology 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 3 ?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. This article is protected by copyright. All rights reserved.
... Addressing both first-and second-order effects of nonstationarity greatly expands the domain of hydrologic inquiry, and generates a series of new challenges of its own: (i) identifying whether or not systems are coupled to each other; (ii) describing the mechanisms that mediate this coupling; and (iii) parameterizing these functional relationships. The explosion of research activity in interdisciplinary subfields of hydrology-ecohydrology (Smettem, 2008;Rodriguez-Iturbe, 2000), eco-geomorphology (Wheaton et al., 2011), eco-hydraulics (Nepf, 2012), hydro-climatology (DeAngelis et al., 2010), hydro-pedology (Lin et al., 2005), and socio-hydrology (Sivapalan et al., 2012) subsystems. However it is unclear whether the processes generally targeted by interdisciplinary hydrology describe all relevant interactions exhaustively. ...
Globally, many different kinds of water resources management issues call for
policy- and infrastructure-based responses. Yet responsible decision-making
about water resources management raises a fundamental challenge for
hydrologists: making predictions about water resources on decadal- to century-long timescales. Obtaining insight into hydrologic futures over 100 yr
timescales forces researchers to address internal and exogenous changes in
the properties of hydrologic systems. To do this, new hydrologic research
must identify, describe and model feedbacks between water and other
changing, coupled environmental subsystems. These models must be constrained
to yield useful insights, despite the many likely sources of uncertainty in
their predictions. Chief among these uncertainties are the impacts of the
increasing role of human intervention in the global water cycle – a
defining challenge for hydrology in the Anthropocene. Here we present a
research agenda that proposes a suite of strategies to address these
challenges from the perspectives of hydrologic science research. The
research agenda focuses on the development of co-evolutionary hydrologic
modeling to explore coupling across systems, and to address the implications
of this coupling on the long-time behavior of the coupled systems. Three
research directions support the development of these models: hydrologic
reconstruction, comparative hydrology and model-data learning. These
strategies focus on understanding hydrologic processes and feedbacks over
long timescales, across many locations, and through strategic coupling of
observational and model data in specific systems. We highlight the value of
use-inspired and team-based science that is motivated by real-world
hydrologic problems but targets improvements in fundamental understanding to
support decision-making and management. Fully realizing the potential of
this approach will ultimately require detailed integration of social science
and physical science understanding of water systems, and is a priority for
the developing field of sociohydrology.
... Following the approach proposed by Wheaton et al. [66] , we analysed the trends of published articles containing the above terms ( Fig. 2 b), considering both the alternative ending in "-morphology" and "-morphodynamics" (hereafter reported as "-morph…"). The numbers are scaled with a reference set containing the total number of articles that refer to fluvial and estuarine environments ( Fig. 2 a). ...
... It is consequently essential for promoting both, litter decomposition (Hättenschwiler and Gasser 2005) and physical–chemical soil parameters (Gabet et al. 2003). Therefore, these organisms have the potential to influence geomorphological processes like soil erosion ( Wheaton et al. 2011; Butler 1995). recently linked ecological principles to geomorphological aspects in general. ...
Soil erosion is a serious environmental problem in many parts of the world, especially in ecosystems with high anthropogenic influences. It is also a serious challenge in subtropical China, but forest stands mitigate soil loss rates in this area. Forests provide a multi-storey canopy layer which largely influences rain throughfall patterns as well as a leaf litter layer on the forest floor which protects the soil against direct raindrop impact and modifies the water flow and storage capacities. Nevertheless, only little research has been conducted on biodiversity and species effects on soil erosion control under forest stands. Furthermore, the processes within a protective leaf litter cover as well as the impact of soil mesofauna and macrofauna are not yet clear.
This thesis investigated the effects of species diversity, species identity, functional traits and soil fauna on soil erosion in subtropical forest ecosystems. It focused on interrill soil erosion rates determined by micro-scale ROPs under natural and simulated rainfall. Additionally, investigations with splash cups were carried out on changes in throughfall kinetic energy during the canopy passage of raindrops. Measurements took place in a forest biodiversity and ecosystem functioning experiment in the PR China (BEF China).
Results showed that tree species richness did not affect sediment discharge, runoff and TKE, although a negative trend was visible. This could be attributed to an absence of species richness effects on canopy characteristics in early successional forest stands. Nevertheless, stands with multiple species seemed to ensure a more balanced and homogenous soil cover. Furthermore, results showed that leaf litter species diversity did not influence the litter cover and thus soil erosion rates. Nonetheless, we could show that species identity influenced initial soil erosion processes under forest. That also applied to the leaf litter cover, where single leaf species showed significantly different influences on sediment discharge. Therefore, the appropriate choice of tree species during the establishment of plantations plays a major role in erosion control, even in young forest stages. Moreover, species-specific functional traits affected soil erosion rates. High crown cover and leaf area index reduced soil erosion, whereas it was slightly increased by increasing tree height. Investigations on the kinetic energy of raindrops showed that low LAI, low tree height, simple pinnate leaves, dentate leaf margins, a high number of branches and a low crown base height effectively minimized TKE. At last, the presence of soil mesofauna and macrofauna increased soil erosion and thus effects of this fauna group on sediment discharge have to be considered in soil erosion experiments.
... Energy from life rather than from elevation can make significant contributions to sediment fluxes. Wheaton et al., 2011;Beschta and Ripple, 2012] that have implications for the responsible organisms and the wider ecosystem [ecosystem engineering: Jones et al., 1994;Wright and Jones, 2006;Moore, 2006;Jones, 2012]. Despite increasing recognition of zoogeomorphological activity there is a pervasive but untested assumption that the impact of animals on sediment flux is minor relative to geophysical forcing. ...
Sediment transport is regarded as an abiotic process driven by geophysical energy, but zoogeomorphological activity indicates that biological energy can also fuel sediment movements. It is therefore prudent to measure the contribution that biota make to sediment transport, but comparisons of abiotic and biotic sediment flux are rare. For a stream in the UK, the contribution of crayfish bioturbation to suspended sediment flux was compared with the amount of sediment moved by hydraulic forcing. During baseflow periods, biotic fluxes can be isolated because nocturnal crayfish activity drives diel turbidity cycles, such that night-time increases above day-time lows are attributable to sediment suspension by crayfish. On average, crayfish bioturbation contributed at least 36% (430 kg) to monthly baseflow suspended sediment loads; this biotic surcharge added between 4.7 and 13.54 t (0.19 to 0.55 t km-2 yr-1) to the annual sediment yield. As anticipated, most sediment was moved by hydraulic forcing during floods and the biotic contribution from baseflow periods represented between 0.43 and 1.24% of the annual load, but this may be a conservative estimate because of unusually prolonged flooding during the measurement period. In addition, we measured direct entrainment of sediment by crayfish, not their potentially greater role in making mobile sediment available to floods via burrowing. These results suggest that in rivers, during baseflow periods, bioturbation can entrain significant quantities of fine sediment into suspension with implications for the aquatic ecosystem and baseflow sediment fluxes. Energy from life rather than from elevation can make significant contributions to sediment fluxes.
... D'Alpaos). between water fluxes, sediment transport, and vegetation dynamics 6 is an important and fascinating question [53] [60] [63] [75], which, how- 7 ever, has remained rather unexplored [18]. In the case of salt-marsh 8 landscapes the issue is relevant also because salt marshes provide 9 a substantial ecological and economic value: They provide a signif-10 icant part of coastal primary production, are characterized by high 11 biodiversity, and deliver valuable ecosystem services [7] [42] [77]. ...
... Simultaneously the activities of biota can affect the nature and rates of geomorphological processes (Viles, 1988;Butler, 1995;Naiman et al., 2000;Reinhardt et al., 2010). While the potential importance of this biotic-abiotic interaction for Earth surface sediment dynamics has been widely discussed (Darby, 2009;Hession et al., 2010;Wheaton et al., 2011;Rice et al., 2012b), understanding of the impact of biota on sediment transport processes, landform generation and sediment yields remains rudimentary. ...
Benthic foraging by fish can modify the nature and rates of fine sediment accrual and the structure and topography of coarse-grained fluvial substrates, with the potential to alter bed material characteristics, particle entrainment thresholds, and bedload transport fluxes. However, knowledge of what controls the nature, extent, and intensity of benthic foraging and the consequent influence of these controls on geomorphic impact remain rudimentary. An ex-situ experiment utilising Barbel Barbus barbus and Chub Leuciscus cephalus extended previous work by considering the role of fish size and species as controls of sediment disturbance by foraging and the implications for bed material characteristics and bedload transport. In a laboratory flume, changes in bed microtopography and structure were measured when a water-worked bed of 5.6–22.6 mm gravels was exposed to four size classes of Barbel (4–5″, 5–6″, 6–8″, 8–10″ in length) and a single size class of Chub (8–10″). In line with other studies that have investigated animal size as a control of zoogeomorphic agency, increasing the size of Barbel had a significant effect on measured disturbance and transport metrics. Specifically, the area of disturbed substrate, foraging depth, and the fish's impact on microtopographic roughness and imbrication all increased as a function of fish size. In a comparison of the foraging effects of like-sized Barbel and Chub, 8–10″ in length, Barbel foraged a larger area of the test bed and had a greater impact on microtopographic roughness and sediment structure. Relative to water-worked beds that were not foraged, bed conditioning by both species was associated with increased bedload transport during the subsequent application of high flows. However, the bedload flux after foraging by Barbel, which is a specialist benthivore, was 150% higher than that following foraging by Chub, which feed opportunistically from the bed, and the total transported mass of sediment was 98% greater. An interesting implication of these results, given the abundance and widespread distribution of foraging fish, is that numerous fish species belonging to a variety of functional groups may be acting as zoogeomorphic agents in rivers, directly affecting bed material conditions and sediment transport fluxes in proportion to their body size and feeding traits.
... El paradigma que aquí se presenta, " medicina fluvial " , se erige como una herramienta de gran utilidad en la gestión de ríos. El paradigma considera a la geomorfología como un elemento primordial dentro de un sistema fluvial (Brierley y Fryirs, 2005; Wheaton et al., 2011). Desde una óptica jerárquica, todo sistema fluvial está condicionado por las componentes climática y, muy especialmente, estructural, esto es, la litología y la tectónica (Montgomery, 1996). ...
Resumen Se establece una metáfora entre salud humana y salud del ecosistema fluvial. El concepto de salud del río (salud del ecosistema) alude al estado de naturalidad en que se encuentra un sistema natural, y cómo podría equiparase con una persona enferma que necesita ayuda para la plena recuperación de sus condiciones fisiológicas (restauración fluvial). Abstract A metaphor between human health and health of the river ecosystem is established. The concept of river health (ecosystem health) refers to the state of naturalness that is a natural system, and how it could be equated with a sick person who needs help for full recovery of their physiological conditions (river restoration).
... Further, the available geomorphic understanding needs to be integrated with other disciplines to enable a better understanding for the sustainable management of the large river systems. Especially, geomorphology-ecology relationship has become an important issue for the assessment of the ecological health of a river, as well as for determining the role of anthropogenic influences 134,[147][148][149][150] . Geomorphology plays an important role in this research area as landscape/landform and its changes determine the type of ecosystem. ...
Significant advances have been made towards understanding the dynamics of geomorphic systems through the development of new concepts. In the last two decades, these developments were partly guided by the change in the scale of geomorphic analysis from local (landform) to regional (landscape) scale and partly due to the emergence of new scientific tools and quantitative models. The process-based understanding of some geomorphic systems of the Indian subcontinent has also advanced in a significant way and a substantial dataset is now available, especially on the Ganga river system. However, conceptual advancements in geomorphic studies have not been incorporated with the available database on large river systems, especially the Ganga river basin. This article attempts to provide a brief review of geomorphic concepts, i.e. scale, magnitude- frequency, equilibrium, threshold, hierarchy, sensitivity, connectivity, nonlinearity, complexity and multidisciplinarity, and their application for understanding the geomorphology of a large river system, i.e. the Ganga river system. This re-evaluation and synthesis of the geomorphic data of the Ganga riverscape provides useful insights into the dynamics of this multi-scale dispersal system, and thereby also helps in the identification of gaps in knowledge that need to be addressed on a priority basis. The major gaps at longer timescales (103-105 years) include lack of understanding of connectivity in river response to external forcing, the quantification of threshold of geomorphic change, and the integration of data across scales in terms of forms and processes. At modern timescale, the major challenge is to integrate the geomorphic dataset with ecological and hydrological attributes in order to develop a holistic understanding of rivers for their management.
... It is consequently essential for promoting both, litter decomposition (Hättenschwiler and Gasser 2005) and physical–chemical soil parameters (Gabet et al., 2003). By that, these organisms have the potential to influence geomorphological processes like soil erosion (Butler 1995; Wheaton et al., 2011; Butler and Sawyer 2012). Allen et al. (2014) recently linked ecological principles to geomorphological aspects in general. ...
Although the protective role of leaf litter cover against soil erosion is known for a long time, little research has been conducted on the processes involved. Moreover, the impact of soil meso- and macrofauna within the litter layer on erosion control is not clear. To investigate how leaf litter cover and diversity as well as meso- and macrofauna influence sediment discharge in subtropical forest ecosystems, a field experiment has been carried out in South-East China. A full-factorial random design with 96 micro-scale runoff plots and 7 domestic leaf species was established and erosion was triggered by a rainfall simulator. Our results demonstrate that leaf litter cover protects soil from erosion (-82 % sediment discharge on leaf covered plots) by rainfall and this protection is removed as litter decomposes. This protective effect is influenced by the presence or absence of soil meso- and macrofauna. Fauna presence increases soil erosion rates significantly by 58 %, while leaf species diversity shows a non-significant negative trend. We assume that the faunal effect arises from arthropods slackening and processing the soil surface as well as fragmenting and decomposing the protecting leaf litter covers. Even though the diversity level did not show a significant influence, single leaf species in monocultures show rather different impacts on sediment discharge and thus, erosion control. In our experiment, runoff plots with leaf litter from Machilus thunbergii showed the highest sediment discharge (68.0 g/m2) whereas plots with Cyclobalanopsis glauca showed the smallest rates (7.9 g/m2).
... Ecologically, physical disturbances result in the death or displacement of resident organisms56 . Recent literature has emphasized the basis of [7], the need for [8], and results from (see [9] for review) studies that investigate interactions between abiotic and biotic responses to physical disturbance in order to describe how the timing and intensity of habitat disturbance, controlled by spatial and temporal variability in geomorphic processes, play an essential role in structuring biological communities. In the context of dam removal, the sediment pulse released with decommissioning a dam can be considered a discrete event that acts as both a geomorphic and an ecological disturbance [10], and the biotic and abiotic responses to that disturbance can vary depending on the sensitivity of individual reaches to disturbance [11]. ...
Dams are known to impact river channels and ecosystems, both during their lifetime and in their decommissioning. In this study, we applied a before-after-control-impact design associated with two small dam removals to investigate abiotic and biotic recovery trajectories from both the elimination of the press disturbance associated with the presence of dams and the introduction of a pulse disturbance associated with removal of dams. The two case studies represent different geomorphic and ecological conditions that we expected to represent low and high sensitivities to the pulse disturbance of dam removal: the 4 m tall, gravel-filled Brownsville Dam on the wadeable Calapooia River and the 12.5 m tall, sand and gravel-filled Savage Rapids Dam on the largely non-wadeable Rogue River. We evaluated both geomorphic and ecological responses annually for two years post removal, and asked if functional traits of the macroinvertebrate assemblages provided more persistent signals of ecological disturbance than taxonomically defined assemblages over the period of study. Results indicate that: 1) the presence of the dams constituted a strong ecological press disturbance to the near-downstream reaches on both rivers, despite the fact that both rivers passed unregulated flow and sediment during the high flow season; 2) ecological recovery from this press disturbance occurred within the year following the restoration action of dam removal, whereas signals of geomorphic disturbance from the pulse of released sediment persisted two years post-removal, and 3) the strength of the press disturbance and the rapid ecological recovery were detected regardless of whether recovery was assessed by taxonomic or functional assemblages and for both case studies, in spite of their different geomorphic settings.
... In recent years, much work has been done on feedbacks in "biogeomorphology" and/or "ecogeomorphology" (Fisher et al. 2007, Darby 2010, Hession et al. 2010, Reinhardt et al. 2010, Rice et al. 2010b, Wheaton et al. 2011, Schoelynck et al. 2012. ...
Physical modelling is a key tool for generating understanding of the complex interactions between aquatic organisms and hydraulics, which is important for management of aquatic environments under environmental change and our ability to exploit ecosystem services. Many aspects of this field remain poorly understood and the use of physical models within eco-hydraulics requires advancement in methodological application and substantive understanding. This paper presents a review of the emergent themes from a workshop tasked with identifying the future infrastructure requirements of the next generation of eco-hydraulics researchers. The identified themes are: abiotic factors, adaptation, complexity and feedback, variation, and scale and scaling. The paper examines these themes and identifies how progress on each of them is key to existing and future efforts to progress our knowledge of eco-hydraulic interactions. Examples are drawn from studies on biofilms, plants, and sessile and mobile fauna in shallow water fluvial and marine environments. Examples of research gaps and directions for educational, infrastructural and technological advance are also presented.
... In recent years, much work has been done on feedbacks in "biogeomorphology" and/or "ecogeomorphology" (Fisher et al. 2007, Darby 2010, Hession et al. 2010, Reinhardt et al. 2010, Rice et al. 2010b, Wheaton et al. 2011, Schoelynck et al. 2012. ...
... Simultaneously the activities of biota can affect the nature and rates of geomorphological processes (Viles, 1988;Butler, 1995;Naiman et al., 2000;Reinhardt et al., 2010). While the potential importance of this biotic-abiotic interaction for Earth surface sediment dynamics has been widely discussed (Darby, 2009;Hession et al., 2010;Wheaton et al., 2011;Rice et al., 2012b), understanding of the impact of biota on sediment transport processes, landform generation and sediment yields remains rudimentary. ...
The plants and animals that inhabit river channels may act as zoogeomorphic agents affecting the nature and rates of sediment recruitment, transport and deposition. The impact of benthic-feeding fish, which disturb bed material sediments during their search for food, has received very little attention, even though benthic feeding species are widespread in rivers and may collectively expend significant amounts of energy foraging across the bed. An ex-situ experiment was conducted to investigate the impact of a benthic feeding fish (Barbel Barbus barbus) on particle displacements, bed sediment structures, gravel entrainment and transport fluxes. In a laboratory flume changes in bed surface topography were measured and grain displacements examined when an imbricated, water-worked bed of 5.6-16 mm gravels was exposed to feeding juvenile Barbel (on average, 0.195 m in length). Grain entrainment rates and bedload fluxes were measured under a moderate transport regime for substrates that had been exposed to feeding fish and control substrates which had not. On average, approximately 37% of the substrate, by area, was modified by foraging fish during a four-hour treatment period, resulting in increased microtopographic roughness and reduced particle imbrication. Structural changes by fish corresponded with an average increase in bed load flux of 60% under entrainment flows, whilst on average the total number of grains transported during the entrainment phase was 82% higher from substrates that had been disturbed by Barbel. Together, these results indicate that by increasing surface microtopography and undoing the naturally stable structures produced by water working, foraging can increase the mobility of gravel bed materials. An interesting implication of this result is that by increasing the quantity of available, transportable sediment and lowering entrainment thresholds, benthic feeding might affect bedload fluxes in gravel-bed rivers. The evidence presented here is sufficient to suggest that further investigation of this possibility is warranted. This article is protected by copyright. All rights reserved.
... We seek to complement the existing literature reviews that detail the mean and turbulent flow fields over and through extended patches of aquatic vegetation (Nepf, 2012), the abiotic factors influencing plant species dynamics, aquatic habitat, and plant communities (Bornette and Puijalon, 2011), detailed dynamics operating in marshes (Andrea, 2011;Larsen and Harvey, 2011), and physical-biological feedbacks in ecogeomorphology (Darby, 2011;Reinhardt et al., 2010;Wheaton et al., 2011). Feedback between woody debris accumulations, sediment storage, and channel hydraulics at the reach scale has been documented for steep and low sloped channels (Abbe and Montgomery, 1996;Bennett et al., 2008), and recent research has quantified and correlated the distribution and transport of individual wood pieces and wood jams with channel planform morphology (Curran, 2010;Moulin et al., 2011). ...
... Biogeomorphology (Viles, 1988;Hupp et al., 1995;Naylor et al., 2002;Stallins, 2006;Francis et al., 2009;Stine and Butler, 2012) and ecogeomorphology/ecomorphology (Frothingham et al., 2002;Thoms and Parsons, 2002;Parsons et al., 2003;Fisher et al., 2007;Murray et al., 2008) are the terms most widely used for describing the study of bidirectional influences of geomorphic and biologic processes on each other. Other common interdisciplinary riverine-related terms include ecohydrology, hydroecology (Baird and Wilby, 1999;Kundzewicz, 2002;Hannah et al., 2004) and hydrogeomorphology (Sidle and Onda, 2004;Wheaton et al., 2011); however, the former two lack a geomorphic element, whereas the latter lacks a distinct biological inference. Clarke et al. (2003) and Vaughan et al. (2009) suggested the development of an ecohydromorphology field of river sciences which is defined as 'the interactions of the biological entities and ecological processes of a river with the hydrological and geomorphological forms and dynamics'. ...
... Addressing both first-and second-order effects of nonstationarity greatly expands the domain of hydrologic inquiry, and generates a series of new challenges of its own: (i) identifying whether or not systems are coupled to each other; (ii) describing the mechanisms that mediate this coupling; and (iii) parameterizing these functional relationships. The explosion of research activity in interdisciplinary subfields of hydrology-ecohydrology (Smettem, 2008;Rodriguez-Iturbe, 2000), eco-geomorphology (Wheaton et al., 2011), eco-hydraulics (Nepf, 2012), hydro-climatology (DeAngelis et al., 2010), hydro-pedology (Lin et al., 2005), and socio-hydrology (Sivapalan et al., 2012) subsystems. However it is unclear whether the processes generally targeted by interdisciplinary hydrology describe all relevant interactions exhaustively. ...
Globally, many different kinds of water resources management issues call
for policy and infrastructure based responses. Yet responsible decision
making about water resources management raises a fundamental challenge
for hydrologists: making predictions about water resources on
decadal-to-century long timescales. Obtaining insight into hydrologic
futures over 100 yr timescales forces researchers to address internal
and exogenous changes in the properties of hydrologic systems. To do
this, new hydrologic research must identify, describe and model
feedbacks between water and other changing, coupled environmental
subsystems. These models must be constrained to yield useful insights,
despite the many likely sources of uncertainty in their predictions.
Chief among these uncertainties are the impacts of the increasing role
of human intervention in the global water cycle - a defining challenge
for hydrology in the Anthropocene. Here we present a research agenda
that proposes a suite of strategies to address these challenges. The
research agenda focuses on the development of co-evolutionary hydrologic
modeling to explore coupling across systems, and to address the
implications of this coupling on the long-time behavior of the coupled
systems. Three research directions support the development of these
models: hydrologic reconstruction, comparative hydrology and model-data
learning. These strategies focus on understanding hydrologic processes
and feedbacks over long timescales, across many locations, and through
strategic coupling of observational and model data in specific systems.
We highlight the value of use-inspired and team-based science that is
motivated by real-world hydrologic problems but targets improvements in
fundamental understanding to support decision-making and management.
... The actively developing discipline of biogeomorphology (cf. Wheaton et al., 2011) offers a large potential to enhance this understanding by jointly investigating vegetation and geomorphic dynamics in glacier forefields. The term 'biogeomorphology' was coined by Viles (1988, p. 1) as 'approach to geomorphology which considers the role of organisms.' ...
... [2] Ecogeomorphologic systems exhibit highly nonlinear interactions between physical and biological factors [National Research Council, 2010;Wheaton et al., 2011] that lead to the emergence of remarkable and intriguing landform-vegetation patterns [Corenblit and Steiger, 2009;Reinhardt et al., 2010;Saco and Rodriguez, 2013]. These self-organizing patterns result from the coevolution of landforms and biota, which makes the understanding and prediction of landscape responses to change highly challenging. ...
[1] Nonlinear interactions between physical and biological factors give rise to the emergence of remarkable landform-vegetation patterns. Patterns of vegetation and resource redistribution are linked to productivity and carrying capacity of the land. As a consequence, growing concern over ecosystem resilience to perturbations that could lead to irreversible land degradation imposes a pressing need for understanding the processes, nonlinear interactions, and feedbacks, leading to the coevolution of these patterns. For arid and semiarid regions, causes for concern have increased at a rapid pace during the last few decades due to growing anthropic and climatic pressures that have resulted in the degradation of numerous areas worldwide. This paper aims at improving our understanding of the ecogeomorphic evolution of landscape patterns in semiarid areas with a sparse biomass cover through a modeling approach. A coupled vegetation-pattern formation and landform evolution model is used to study the coevolution of vegetation and topography over centennial timescales. Results show that self-organized vegetation patterns strongly depend on feedbacks with coevolving landforms. The resulting patterns depend on the erosion rate and mechanism (dominance of either fluvial or diffusive processes), which are affected by biotic factors. Moreover, results show that ecohydrologic processes leading to banded pattern formation, when coupled with landform processes, can also lead to completely different patterns (stripes of vegetation along drainage lines) that are equally common in semiarid areas. These findings reinforce the importance of analyzing the coevolution of landforms and vegetation to improve our understanding of the patterns and structures found in nature.
Pioneer naturalists such as Whewell, Lyell, Humboldt, Darwin and Wallace acknowledged the interactions between ecological and evolutionary forces, as well as the roles of continental movement, mountain formation and climate variations, in shaping biodiversity patterns. Recent developments in computer modelling and paleo‐environmental reconstruction have made it possible for scientists to study in silico how biodiversity emerges from eco‐evolutionary and environmental dynamic processes and their interactions. Simulating emergent biodiversity enables the experimentation of multiple interconnected hypotheses in a largely fragmented scientific landscape, with the final objective of successfully approximating natural mechanisms (i.e. hypothetical spatio–temporally unrestricted generalizations that hold across multiple empirical biodiversity patterns). This new interdisciplinary approach opens unprecedented scientific pathways, facilitating the communication and contemplation of causal implications of complex eco‐evolutionary and environmental interactions. In this review I provide a comprehensive overview of the available population‐based spatially explicit mechanistic eco‐evolutionary models (MEEMs) that rely on paleo‐environmental reconstructions, critically discussing their relevance and limitations for our understanding of biodiversity. To achieve this, I first introduce diverse biodiversity models and contextualize MEEMs. Second, I define MEEMs and synthesize the major insights from studies using MEEMs combined with deep‐time environmental dynamics (> 0.1 Ma). Lastly, I discuss the challenges and perspectives of solving long‐standing biodiversity enigmas by coupling eco‐evolutionary mechanisms with deep‐time environmental dynamics. Studies show that linking dynamic environments and eco‐evolutionary processes is necessary to reproduce multiple large‐scale biodiversity patterns simultaneously. Mechanisms related to adaptations (e.g. niche evolution), dispersal abilities and other eco‐evolutionary interactions (e.g. those resulting in speciation or extinction events) show universal importance, although their signatures across spatial and temporal scales remain largely unknown. Investigations with MEEMS spanning multiple levels of complexity in space and time foster interdisciplinary cooperation across the natural sciences and show promise for solving some of the enigmas in Earth's biodiversity.
Over the last several decades, the study of Earth surface processes has progressed from a descriptive science to an increasingly quantitative one due to advances in theoretical, experimental, and computational geosciences. The importance of geomorphic forecasts has never been greater, as technological development and global climate change threaten to reshape the landscapes that support human societies and natural ecosystems. Here we explore best practices for developing socially-relevant forecasts of Earth surface change, a goal we are calling “earthcasting”. We suggest that earthcasts have the following features: they focus on temporal (~1 to ~100 years) and spatial (~1 m to ~10 km) scales relevant to planning; they are designed with direct involvement of stakeholders and public beneficiaries through the evaluation of the socioeconomic impacts of geomorphic processes; and they generate forecasts that are clearly stated, testable, and include quantitative uncertainties. Earthcasts bridge the gap between Earth surface researchers and decision-makers, stakeholders, researchers from other disciplines, and the general public. We investigate the defining features of earthcasts and evaluate some specific examples. This paper builds on previous studies of prediction in geomorphology by recommending a roadmap for (i) generating earthcasts, especially those based on modeling; (ii) transforming a subset of geomorphic research into earthcasts; and (iii) communicating earthcasts beyond the geomorphology research community. Earthcasting exemplifies the social benefit of geomorphology research, and it calls for renewed research efforts toward further understanding the limits of predictability of Earth surface systems and processes, and the uncertainties associated with modeling geomorphic processes and their impacts.
Rivers are complex biophysical systems, constantly adjusting to a suite of changing governing conditions, including vegetation cover within their basins. This review seeks to: (i) highlight the crucial role that vegetation’s influence on the efficiency of clastic material fluxes (geomorphic connectivity) plays in defining mountain fluvial landscape’s behavior; and (ii) identify key challenges which hinder progress in the understanding of this subject. To this end, a selective literature review is carried out to illustrate the pervasiveness of the plants’ effects on geomorphic fluxes within channel networks (longitudinal connectivity), as well as between channels and the broader landscape (lateral connectivity). Taken together, the reviewed evidence lends support to the thesis that vegetation-connectivity linkages play a central role in regulating geomorphic behavior of mountain fluvial systems. The manuscript is concluded by a brief discussion of the need for the integration of mechanistic research into the local feedbacks between plants and sediment fluxes with basin-scale research that considers emergent phenomena.
Soil and regolith creep have been analyzed for at least the last 140 years, using many methodological configurations and temporal and spatial scales. The general concept of creeping soil and its mechanism, first proposed by W.M. Davis and G.K. Gilbert at the end of the 19th century, evolved since the 1940s towards theoretical models and precise short- and long-term field measurements. This fruitful epoch continued with results enhanced at the turn of the 20th century by the application of new research methods (e.g. radiometry) and a redefinition of the term soil creep to encompass the sum of stochastic shallow subsurface and near-surface processes causing net downslope movement of soil or regolith. Simultaneously, another possibility of creep detection was noticed in dendrochronology, and since the 1970s, in the formally defined discipline of dendrogeomorphology, indirect evaluations of creep activity were performed based on tree-ring analyses of bent trees. This method found many followers, but was also heavily criticized as imprecise and lacking in evidence of which kind of tree trunk curvature (e.g. “pistol-butt”- like deformation, S-shape curvature) could be ascribed to creep movement.
From the beginning, soil creep was associated with the activity of living organisms on hillslopes. However, this aspect of creep studies has never been fully developed, in spite of the solid foundations and directions of potential studies pointed out by Charles Darwin at the end of the 19th century.
In this paper we focus on the historical context of soil creep studies, and highlight forest ecosystems as probably the most active environment of biogenic creep, mainly due to tree uprooting and other biomechanical effects of living and dead trees (root channel infilling, tree root mounding etc.) that are a factors in biotransport. In the final sections the position of biogenic creep in the structure of biogeomorphic systems is discussed in relation to such important conceptual frameworks as the biogeomorphic ecosystem, biogeomorphic feedback window and ecosystem engineering. We also describe several hypotheses that should be carefully tested in the future, and propose several research methods that have the ability to further our knowledge about soil creep: radiometry, laser scanning and soil micromorphology.
A perspective is given on important themes in geomorphology over the last decade and the challenges ahead. Earth System Science and Earth Surface Processes are wider research themes through which the profile of geomorphology is emphasized. Developments in areas of landscape and catchment modeling, extraterrestrial geomorphology, and biogeomorphology illustrate the integrative and scale-transgressive character of geomorphology. Advances in technologies for data acquisition, handling, and visualization are providing information at unprecedented scales and resolutions. Aeolian geomorphology has experienced resurgence largely due to data on extraterrestrial surfaces. Dating has progressed through optically stimulated luminescence and terrestrial cosmogenic nuclide dating applications, and the development of age models.
The biogeosciences are a rapidly expanding field, and for this reason the full scope of possible topics falling under this heading is not always recognized. The biogeosciences cover all fields of the biological sciences and their interactions with the relevant Earth spheres (i.e. atmosphere, hydrosphere, lithosphere), and are studied over a wide range of temporal and spatial scales. While interdisciplinary work has been recognized for many years, it is recommended that all biogeosciences studies should ultimately strive to understand process operation and feedbacks, and in doing so a common ground to approaches of study can be defined. The notion of multidisciplinary versus interdisciplinary research is considered herein. It is by following an approach of explanation-based science that the complex interplay of biological and environmental processes can be understood best. Understanding of system behaviour and functioning should be a core goal of biogeosciences research. This review offers a proposed classification and summary of the full range of topics falling under the umbrella of the biogeosciences, and in doing so sets the stage for a future series of progress reports focusing on recent developments in the biogeosciences.
An important and highly active research agenda has developed at the interface of fluvial geomorphology and ecology that addresses the capacity for vegetation and animals to act as ecosystem engineers within fluvial systems. This paper briefly introduces this research domain and describes the fifteen papers that contribute to the special issue on ‘Dynamic riverine landscapes: the role of ecosystem engineers’. The papers illustrate the breadth of research activity at this interface, investigating the influence of a range of ecosystem engineering organisms through a combination of field study, laboratory experiments, numerical simulation and analysis of remotely sensed data. Together, the papers address a series of key themes: conceptual frameworks for feedbacks between aquatic biota, hydraulics, sediment dynamics and nutrient dynamics and their quantification through experimental and field research; the potential contribution of ecosystem engineering species to assist river recovery and restoration; and the contribution of riparian vegetation to bank stability and morphodynamics across a range of spatio-temporal scales. This article is protected by copyright. All rights reserved.
Ecosystem health metrics quantify the cumulative effects of stressors on ecosystem structure and function, and inform management, restoration, and policy decisions. Freshwater ecosystems, in particular, face numerous stressors, and as a result, there is an increasing array of health metrics applied to their management. In this chapter, we review the current use of ecosystem health metrics, develop a preliminary framework for metric selection, and identify gaps in the current suite of metrics. The existing metrics typically characterize the biological, physical, or chemical attributes of ecosystems, whereas a few additional metrics integrate across these categories. Metrics vary in complexity, ranging from simple, visual assessments that can be completed by volunteers, to complex numerical models with extensive data and expert input requirements. Overall, ecosystem health metrics are well developed and useful with metrics available to fit both general and specialized management needs. However, common challenges include difficulty in establishing suitable reference conditions, a lack of uncertainty estimates, and a lack of inter-metric comparisons. Recent technological improvements, such as remote sensing, computational models, and new genetic sequencing techniques, are facilitating the development of novel and more holistic metrics, including early warning metrics, coupled complex systems models, and the inclusion of public input data.
This chapter uses ecohydraulic analysis of 2D model results in a numerical experiment to test the relative merits of building sequences of riffle-pool units in regulated gravel-bed rivers rehabilitation with different magnitudes of riffle-pool relief. It assess the consequences of high versus low riffle-pool relief on (i) physical habitat quality for Chinook salmon and steelhead trout in their sensitive spawning and fry life stages at the regulated discharge typical for the periods when those life stages occur and (ii) sediment transport regimes during two geomorphically and ecologically significant flows. A third objective looks beyond relief to assess how the consequences from objectives (i) and (ii) vary between different riffle-pool shapes. The discharges focused on were flows associated with bed occupation during the freshwater reproductive cycle and physical-habitat rejuvenation during prescribed spring snowmelt releases, using the highest regulated release as of December 2004.
Over the last century, large-scale water development of the upper Rio Grande in the U.S. and Mexico, and of the Rio Conchos in Mexico, has resulted in progressive channel narrowing of the lower Rio Grande in the Big Bend region. We used methods operating at multiple spatial and temporal scales to analyze the rate, magnitude, and processes responsible for channel narrowing. These methods included: hydrologic analysis of historic stream gage data, analysis of notes of measured discharges, historic oblique and aerial photograph analysis, and stratigraphic and dendrogeomorphic analysis of inset floodplain deposits. Our analyses indicate that frequent large floods between 1900 and the mid-1940s acted as a negative feedback mechanism and maintained a wide, sandy, multi-threaded river. Declines in mean and peak flow in the mid-1940s resulted in progressive channel narrowing. Channel narrowing has been temporarily interrupted by occasional large floods that widened the channel, however, channel narrowing has always resumed. After large floods in 1990 and 1991, the active channel width of the lower Rio Grande has narrowed by 36–52%. Narrowing has occurred by the vertical accretion of fine-grained deposits on top of sand and gravel bars, inset within natural levees. Channel narrowing by vertical accretion occurred simultaneously with a rapid invasion of non-native riparian vegetation (Tamarix spp., Arundo donax) which created a positive feedback and exacerbated the processes of channel narrowing and vertical accretion. In two floodplain trenches, we measured 2.75 and 3.5 m of vertical accretion between 1993 and 2008. In some localities, nearly 90% of bare, active channel bars were converted to vegetated floodplain during the same period. Upward shifts of stage-discharge relations occurred resulting in over-bank flooding at lower discharges, and continued vertical accretion despite a progressive reduction in stream flow. Thus, although the magnitude of the average annual flood was reduced between 40 and 50%, over-bank flooding continued. These changes reflect a shift in the geomorphic nature of the Rio Grande from a wide, laterally unstable, multi-thread river, to a laterally stable, single-thread channel with cohesive, vertical banks, and few active in-channel bars.
1] Plants and animals affect morphological evolution in many environments. The term ''ecogeomorphology'' describes studies that address such effects. In this opinion article we use the term ''biomorphodynamics'' to characterize a subset of ecogeomorphologic studies: those that investigate not only the effects of organisms on physical processes and morphology but also how the biological processes depend on morphology and physical forcing. The two-way coupling precipitates feedbacks, leading to interesting modes of behavior, much like the coupling between flow/sediment transport and morphology leads to rich morphodynamic behaviors. Select examples illustrate how even the basic aspects of some systems cannot be understood without considering biomorphodynamic coupling. Prominent examples include the dynamic interactions between vegetation and flow/ sediment transport that can determine river channel patterns and the multifaceted biomorphodynamic feedbacks shaping tidal marshes and channel networks. These examples suggest that the effects of morphology and physical processes on biology tend to operate over the timescale of the evolution of the morphological pattern. Thus, in field studies, which represent a snapshot in the pattern evolution, these effects are often not as obvious as the effects of biology on physical processes. However, numerical modeling indicates that the influences on biology from physical processes can play a key role in shaping landscapes and that even local and temporary vegetation disturbances can steer large-scale, long-term landscape evolution. The prevalence of biomorphodynamic research is burgeoning in recent years, driven by societal need and a confluence of complex systems–inspired modeling approaches in ecology and geomorphology. To make fundamental progress in understanding the dynamics of many landscapes, our community needs to increasingly learn to look for two-way, biomorphodynamic feedbacks and to collect new types of data to support the modeling of such emergent interactions.
There appears to be no single axis of causality between life and its landscape, but rather, each exerts a simultaneous influence on the other over a wide range of temporal and spatial scales. These influences occur through feedbacks of differing strength and importance with co-evolution representing the tightest coupling between biological and geomorphological systems. The ongoing failure to incorporate these dynamic bio-physical interactions with human activity in landscape studies limits our ability to predict the response of landscapes to human disturbance and climate change. This limitation is a direct result of the poor communication between the ecological and geomorphological communities and consequent paucity of interdisciplinary research. Recognition of this failure led to the organization of the Meeting of Young Researchers in Earth Science (MYRES) III, titled ‘Dynamic Interactions of Life and its Landscape’. This paper synthesizes and expands upon key issues and findings from that meeting, to help chart a course for future collaboration among Earth surface scientists and ecologists: it represents the consensus view of a competitively selected group of 77 early-career researchers. Two broad themes that serve to focus and motivate future research are identified: (1) co-evolution of landforms and biological communities; and (2) humans as modifiers of the landscape (through direct and indirect actions). Also outlined are the state of the art in analytical, experimental and modelling techniques in ecological and geomorphological research, and novel new research avenues that combine these techniques are suggested. It is hoped that this paper will serve as an interdisciplinary reference for geomorphologists and ecologists looking to learn more about the other field. Copyright © 2010 John Wiley & Sons, Ltd.
Strong feedbacks exist between physical and ecological components of aquatic systems. Aquatic plants can alter flow and sedimentation patterns, in turn influencing habitat condition and organism responses. In this study, I investigate the interactions between streambed periphyton, particle deposition and infiltration, and flow hydraulics to determine the influence of these organisms on the local environment. In a series of flume experiments, I measured the effects of two contrasting forms of periphyton at several densities and growth stages on near-bed hydraulics, particle loss from the water column, surface deposition, and subsurface infiltration. Data show that periphyton assemblages altered the rate and quantity of particle deposition via several mechanisms, including shear stress modification, surface adhesion, and bed clogging. Although trends varied for different size classes within a suspension of fine sediment, diatoms and algae had distinctly different effects on hydraulics, deposition, and infiltration. In general, diatoms increased the rate of decline in suspended particle concentrations relative to non-periphyton surfaces by reducing shear stresses and enhancing surface deposition via adhesion. Increases in diatom biomass, however, reduced the quantity and depth of particle infiltration, presumably by clogging interstitial pore spaces, in turn lowering rates of concentration decline. In contrast, all algal growth stages had slower or similar rates of concentration decline compared to non-periphyton conditions, due to partial clogging by high biomass and a lack of adhesion at the bed surface. Clogging effects were counteracted at later growth stages, however, as late-stage algal structures increased shear stresses and downward advection, in turn increasing amounts of infiltration. Compiled data from several field studies and experiments demonstrate a positive relation between periphyton biomass and inorganic mass, but also show a wide range in the relation because of external factors such as discharge and suspended sediment concentration. My analysis indicates that the decrease in the concentration of suspended particles under controlled conditions is strongly influenced by periphyton structure, through direct mechanisms such as adhesion and clogging as well as indirect changes to hydraulics, but that external factors in field settings such as discharge and sediment supply may outweigh the effects of periphyton structure.
The influence of salmon-derived nutrients (SDN) is widely accepted as a potential factor in the maintenance of aquatic and terrestrial productivity in North American Coastal rainforests. Holocene alluvial landforms are intimately connected with the return of anadromous salmon, but the influence of the soils that occupy these landforms and support this important terrestrial–aquatic ecological coupling have not been examined in SDN studies. We used paleo-ecologic information, soil resource inventories and measurements of soil morphology to construct a soil-geomorphic model for alluvial landforms along salmon spawning channels on Prince of Wales Island, Southeast Alaska, USA. Post-glacial sea-level rise, crustal uplift and subsidence combined with Holocene sediment deposition have formed alluvial terraces and floodplains along rivers on Prince of Wales Island. These alluvial landforms have soils that are mapped as Entisols (Tonowek soil series) and Spodosols (Tuxekan soil series). We propose a soil-geomorphic model where the Spodosols located on terraces are estimated to derive from sediments deposited after the stabilization of landscape approximately 8 kybp to 6 kybp. The stability of these soils is reflected through mature soil development with organic matter accumulation and podzolization. Our model identifies Entisols on floodplains developed from alluvial deposition in the latter Holocene that have soil morphologic features consistent with recent deposition and limited soil development. We used this soil-geomorphic model to test the hypothesis that the terrestrial end-member value commonly used to quantify nitrogen (N) loading on soils through stable isotope analysis differs by soil type and found that the two soil types had significantly different N isotopic (δ15N) values more consistent with soil development than SDN loading. The use of a soil-geomorphic model provides a means to stratify alluvial landforms and constrain the natural variability encountered in studies of riparian nutrient cycles associated with the feedbacks between SDN and terrestrial ecosystems to improve estimates of the fate of SDN in soils and vegetation.
The linkages between fluvial geomorphology and aquatic ecosystems are commonly conceptualized as a one-way causal chain in which geomorphic processes create the physical template for ecological dynamics. In streams with a travertine step-pool morphology, however, biotic processes strongly influence the formation and growth of travertine dams, creating the potential for numerous feedbacks. Here we take advantage of the decommissioning of a hydroelectric project on Fossil Creek, Arizona, where restoration of CaCO3-rich baseflow has triggered rapid regrowth of travertine dams, to explore the interactions between biotic and abiotic factors in travertine morphodynamics. We consider three conceptual frameworks, where biotic factors independently modulate the rate of physical and chemical processes that produce travertine dams; combine with abiotic factors in a set of feedback loops; and work in opposition to abiotic processes, such that the travertine step-pool morphology reflects a dynamic balance between dominantly-biotic constructive processes and dominantly-abiotic destructive processes. We consider separately three phases of an idealized life cycle of travertine dams: dam formation, growth, and destruction by erosive floods. Dam formation is catalyzed by abiotic factors (e.g. channel constrictions, and bedrock steps) and biotic factors (e.g. woody debris, and emergent vegetation). From measurements of changes over time in travertine thickness on a bedrock step, we find evidence for a positive feedback between flow hydraulics and travertine accrual. Measurements of organic content in travertine samples from this step show that algal growth contributes substantially to travertine accumulation and suggest that growth is most rapid during seasonal algal blooms. To document vertical growth of travertine dams, we embedded 252 magnets into nascent travertine dams, along a 10 km stretch of river. Growth rates are calculated from changes over time in the magnetic field intensity at the dam surface. At each magnet we record a range of hydraulic and travertine composition variables to characterize the dominant mechanism of growth: abiotic precipitation, algal growth, trapping of organic material, or in situ plant growth. We find: (1) rapid growth of travertine dams following flow restoration, averaging more than 2 cm/year; (2) growth rates decline downstream, consistent with loss of dissolved constituents because of upstream travertine deposition, but also parallel to a decline in organic content in dam surface material and a downstream shift in dominant biotic mechanism; (3) biotic mechanisms are associated with faster growth rates; and (4) correlations between hydraulic attributes and growth rates are more consistent with biotic than abiotic controls. We conclude that the strong influence of living organisms on rates of travertine growth, coupled with the beneficial effects of travertine on ecosystem dynamics, demonstrate a positive feedback between biology and geomorphology. During our two-year study period, erosive flood flows occurred causing widespread removal of travertine. The temporal distribution of travertine growth and erosion over the study period is consistent with a bimodal magnitude–frequency relation in which growth dominates except when large, infrequent storms occur. This model may be useful in other systems where biology exerts strong controls on geomorphic processes.
Ecohydraulics forms a new multidiscipline that derives from the ever growing needs for water use and a global preoccupation for the survival of natural riverine ecosystems. The greatest challenge ever posed to hydraulicians is to harmonize the design and management of water works with the ecological components of rivers, floodplains and estuaries. While already pre-sent in the IAHR agenda for several decades through fish passage facilities or compensating measures for environmental impacts of civil works, new trends appeared during the last dec-ade based on new public policies (e.g. European Water Management Framework Directive, integrated management at the basin scale), practices and regulations that require from de-signers and managers an enlarged account of environmental preoccupations including conservation flow regimes, modeling of riverine habitats, restoration of natural ecosystems. Acknowledging the urgent need for a new paradigm regarding the cohabitation of water uses and the natural components of hydrosystems, IAHR launched in 1993 a series of confer-ences on habitat hydraulics in Trondheim, Norway (1994). In 1996 at the second ecohydraulics conference in Quebec, a fully-fledged section on Ecohydraulics was created within IAHR. Five international conference events spread over three continents up to now have been held and the topics have continuously grown in importance. This note reports on the genesis of this movement within IAHR, its underlying vision and its recent evolution.
Soil erosion studies reveal a serious lack of understanding of the relationships between processes, sediment yields and erosional landforms on the one hand and vegetation cover on the other. The concept of competition between erosion and vegetational growth, through time and spatially, is outlined then cast in the framework of ecological models. The application of these models to the real world is discussed. -Author
Plants build dunes, and dune growth controls plant growth. Hence we can use the distribution and structure of dune plant indicators to reconstruct recent changes in sand deposition, erosion, and stabilization. This is illustrated by the alternate widening and contraction of foredunes around Lake Michigan during recent decades.
Salt marshes are coastal ecosystems characterized by high biodiversity and rates of primary productivity, providing fundamental ecosystem services. Salt-marsh ecosystems are important indicators of environ-mental change as the dynamics are governed by interacting physical and biological processes, whose intertwined feedbacks critically affect the evolution. Settling deposition of inorganic sediment allows the platform to reach a threshold elevation for vegetation encroachment; the presence of vegetation then intensifies rates of accretion, thus, enhancing the resilience of marshes to increasing rates of sea level rise (SLR). The results from a two-dimensional numerical model, accounting for biotic and geomorphic processes, show that different morphological evolutionary regimes are followed depending on marsh biological processes. The average marsh elevation within the tidal frame decreases with increasing rates of SLR, decreasing availability of sediment, and decreasing productivity of vegetation. The spatial variability in platform elevations increases with increasing rates of SLR, increasing availability of sediment, and decreasing productivity of vegetation. Supply-limited settings tend to develop uniform marsh surface elevations, whereas supply-rich settings tend to develop patterns of sedimentation where large heterogeneities in marsh surface elevations occur. The complexity observed in tidal geomorphological patterns is deemed to arise from the mutual influence of biotic and abiotic components. The fate of tidal landforms and their possible geomorphological restoration should, thus, be addressed through approaches which explicitly incorporate bio-morphodynamic processes.
A national meeting of the British Hydrological Society held at Loughborough University (UK) focused on process interactions between lotic organisms, flow and sediment at scales relevant to organisms. The meeting sought to address how it is possible to scale up results of small (organism) scale research at the interface of ecology, geomorphology and hydrology to improve understanding of river ecology at larger scales. The resulting papers in this special issue represent a broad cross section of the interdisciplinary research on biofilms, plants, macroinvertebrates and fish currently being undertaken in this arena. A survey of conference delegates and bibliographic analysis suggested that ecohydraulics is not a term which attracts the attention of as many biologists and ecologists as it does physical scientists (e.g. water resource engineers and geomorphologists). This may represent a hurdle on the path towards a more integrative, interdisciplinary river science because it suggests a missed opportunity for fruitful exchanges and interactions between physical and biological scientists. In this context, it is notable that one of the papers in this collection includes a passionate call for greater ecological input within the emerging field of ecohydraulics and another presents a hydraulicists view of an appropriate theoretical platform for integrating ecological, hydrodynamic and biomechanical processes. Copyright © 2010 John Wiley & Sons, Ltd.
Channel incision, channel widening, and excessive floodplain sedimentation are major causes of riparian ecosystem degradation across the country. Although the causes and consequences of these processes vary significantly, the resulting morphology in all cases results in a lower stream stage relative to the floodplain surface for any given discharge. This change in channel morphology alters surface water–groundwater interactions between the stream and the riparian aquifer and affects the soil moisture and groundwater regimes differentially across the floodplain. The distribution of vegetation is altered as the hydrologic regime shifts between the hydrologic niches of potential species. We simulate the hydroecologic response of a groundwater-dependent ecosystem on the floodplain of an archetypical watershed under three scenarios representing changes in channel morphology: a base case, a widened channel case, and an incised channel case. Stochastically-driven synthetic rainfall records are used to drive a rainfall–runoff model of the archetype watershed. The resulting hydrograph is transformed to stage via Manning's equation for the three channel morphologies considered. This stage record is used as a boundary condition for a finite-element model simulating 2-dimensional, variably-saturated groundwater flow in the riparian aquifer. The model predicts soil moisture and groundwater regimes lateral to the channel. The 7-day moving average high water level is determined for ten growing seasons and used to predict the distribution of three species across the floodplain. Plant frequency is predicted for Carex emoryi (an obligate wetland species), Carex crawei (facultative wetland species), and Carex duriuscula (a facultative upland species) for each of the channel morphologies considered. The frequency is predicted using existing nonlinear parametric species response curves determined empirically for these species using direct gradient analysis. Results show the sensitivity of the distribution of vegetation on floodplains to channel morphologic changes. Our linked hydrologic and ecological model provides a solid framework for considering potential hydroecologic impacts of channel disturbance and/or restoration on vegetation communities which are often affected by channel degradation and targeted in restoration efforts.
Although biogeomorphological research is well-established, with many studies on a range of two-way interrelations between organisms and geomorphology in different environments, there is little consensus over what constitutes biogeomorphology, why it might be useful and where it is heading. Starting with definitions of core biogeomorphic processes, we consider the need for future biogeomorphological studies to evaluate the crucial links between bioprocesses, biological community dynamics and ‘inorganic’ earth surface processes. Five key applications of biogeomorphological research are identified; the roles of organisms in environmental reconstruction, trace fossil analysis, extraterrestrial geomorphology, environmental engineering and the built environment. Some key research directions and methodological challenges for future biogeomorphological research include expanding the spatial and temporal coverage of datasets, investigating the role of bioprocesses in landform development, tackling scale issues, investigating the relevance of nonlinear dynamical ideas to biogeomorphology and developing better sampling and monitoring techniques for bioprocesses.
Most research before 1960 into interactions among fluvial processes, resulting landforms, and vegetation was descriptive. Since then, however, research has become more detailed and quantitative permitting numerical modeling and applications including agricultural-erosion abatement and rehabilitation of altered bottomlands. Although progress was largely observational, the empiricism increasingly yielded to objective recognition of how vegetation interacts with and influences geomorphic process. A review of advances relating fluvial processes and vegetation during the last 50 years centers on hydrologic reconstructions from tree rings, plant indicators of flow- and flood-frequency parameters, hydrologic controls on plant species, regulation of sediment movement by vegetation, vegetative controls on mass movement, and relations between plant cover and sediment movement.
Connectivity as a concept has been increasingly part of discussions or explanations in hydrology, geomorphology and ecology. We address recent critiques of this approach by demonstrating how a refinement which distinguishes structural connectivity from functional connectivity can be used to explain patterns observed in very different environmental systems. These systems are found in linkages between surface and subsurface flowpaths and the hyporheos in the River Don, a temperate river channel in Yorkshire, UK; in surface and subsurface fluxes in agricultural land in the UK; and in vegetation and surface conditions in a degrading environment at the Sevilleta LTER site in the semi-arid Southwest USA. First, we demonstrate long-term geological and structural controls mediated by in-channel processes. Second, human organization of landscape elements is a significant control on runoff and erosion, so that similar events can produce very different responses (and vice versa). Third, linkages between the removal of grass vegetation and runoff and erosion produce non-linear and path-dependent feedbacks which control the subsequent degradation of the landscape, making the process difficult to reverse. As a result of these studies, we argue that even in cases where connectivity cannot be directly quantified (at least at present), this limitation does not prevent the concept from being a useful heuristic device for exploring responses of complex systems. Furthermore, this result implies that an increasing need exists for disciplinary connectivity to investigate such systems.
Complex nonlinear dynamic systems are ubiquitous in the landscapes and phenomena studied by earth sciences in general and by geomorphology in particular. Concepts of chaos, fractals and self-organization, originating from research in nonlinear dynamics, have proven to be powerful approaches to understanding and modeling the evolution and characteristics of a wide variety of landscapes and bedforms. This paper presents a brief survey of the fundamental ideas and terminology underlying these types of investigations, covering such concepts as strange attractors, fractal dimensions and self-organized criticality. Their application in many areas of geomorphological research is subsequently reviewed, in river network modeling and in surface analysis amongst others, followed by more detailed descriptions of the use of chaos theory, fractals and self-organization in coastal geomorphology in particular. These include self-organized behavior of beach morphology, the fractal nature of ocean surface gravity waves, the self-organization of beach cusps and simulation models of ripples and dune patterns. This paper further presents a substantial extension of existing dune landscape simulation models by incorporating vegetation in the algorithm, enabling more realistic investigations into the self-organization of coastal dune systems. Interactions between vegetation and the sand transport process in the model—such as the modification of erosion and deposition rules and the growth response of vegetation to burial and erosion—introduce additional nonlinear feedback mechanisms that affect the course of self-organization of the simulated landscape. Exploratory modeling efforts show tantalizing results of how vegetation dynamics have a decisive impact on the emerging morphology and—conversely—how the developing landscape affects vegetation patterns. Extended interpretation of the modeling results in terms of attractors is hampered, however, by want of suitable state variables for characterizing vegetated landscapes, with respect to both morphology and vegetation patterns.
Flow interactions with aquatic vegetation and effects on sediment transport and nutrient redistribution are uncertain in shallow aquatic ecosystems. Here we quantified sediment transport in the Everglades by progressively increasing flow velocity in a field flume constructed around undisturbed bed sediment and emergent macrophytes. Suspended sediment < 100 μm was dominant in the lower range of laminar flow and was supplied by detachment from epiphyton. Sediment flux increased by a factor of four and coarse flocculent sediment > 100 μm became dominant at higher velocity steps after a threshold shear stress for bed floc entrainment was exceeded. Shedding of vortices that had formed downstream of plant stems also occurred on that velocity step which promoted additional sediment detachment from epiphyton. Modeling determined that the potentially entrainable sediment reservoir, 46 g m− 2, was similar to the reservoir of epiphyton (66 g m− 2) but smaller than the reservoir of flocculent bed sediment (330 g m− 2). All suspended sediment was enriched in phosphorus (by approximately twenty times) compared with bulk sediment on the bed surface and on plant stems, indicating that the most easily entrainable sediment is also the most nutrient rich (and likely the most biologically active).
It is widely recognized that interactions between vegetation and flow cause the emergence of channel patterns that are distinct from the standard Schumm classification of river channels. Although landscape pattern is known to be linked to ecosystem services such as habitat provision, pollutant removal, and sustaining biodiversity, the mechanisms responsible for the development and stability of different landscape patterns in shallow, vegetated flows have remained poorly understood. Fortunately, recent advances have made possible large-scale models of flow through vegetated environments that can be run over a range of environmental variables and over timescales of millennia. We describe a new, quasi-3D cellular automata model that couples simulations of shallow-water flow, bed shear stresses, sediment transport, and vegetation dynamics in an efficient manner. That efficiency allowed us to apply the model widely in order to determine how different hydroecological feedbacks control landscape pattern and process in various types of wetlands and floodplains. Distinct classes of landscape pattern were uniquely associated with specific types of allogenic and autogenic drivers in wetland flows. Regular, anisotropically patterned wetlands were dominated by allogenic processes (i.e., processes driven by periodic high water levels and flow velocities that redistribute sediment), relative to autogenic processes (e.g., vegetation production, peat accretion, and gravitational erosion). These anistropically patterned wetlands are therefore particularly prone to hydrologic disturbance. Other classes of wetlands that emerged from simulated interactions included maze-patterned, amorphous, and topographically noisy marshes, open marsh with islands, banded string-pool sequences perpendicular to flow, parallel deep and narrow channels flanked by marsh, and ridge-and-slough patterned marsh oriented parallel to flow. Because vegetation both affects and responds to the balance between the transport capacity of the flow and sediment supply, these vegetated systems exhibit a feedback that is not dominant in most rivers. Consequently, unlike in most rivers, it is not possible to predict the “channel pattern” of a vegetated landscape based only on discharge characteristics and sediment supply; the antecedent vegetation pattern and vegetation dynamics must also be known.In general, the stability of different wetland pattern types is most strongly related to factors controlling the erosion and deposition of sediment at vegetation patch edges, the magnitude of sediment redistribution by flow, patch elevation relative to water level, and the variability of erosion rates in vegetation patches with low flow-resistance. As we exemplify in our case-study of the Everglades ridge and slough landscape, feedback between flow and vegetation also causes hysteresis in landscape evolution trajectories that will affect the potential for landscape restoration. Namely, even if the hydrologic conditions that historically produced higher flows are restored, degraded portions of the ridge and slough landscape are unlikely to revert to their former patterning. As wetlands and floodplains worldwide become increasingly threatened by climate change and urbanization, the greater mechanistic understanding of landscape pattern and process that our analysis provides will improve our ability to forecast and manage the behavior of these ecosystems.
This thematic Virtual Special Issue highlights a personal selection of 18 recent (2007–2009) contributions to Earth Surface Processes and Landforms. These papers provide a flavour of recent research that is concerned with furthering our understanding of the many ways in which the biosphere interacts with the physical and chemical processes of sediment transfer/ transformation. Much of this research has focused on understanding the mechanics by which the biota can modulate sediment transport and the strength of earth surface materials, often with the aim of applying that knowledge to enhance bioremediation methods of erosion control. This work continues to be fundamentally important in enhancing our understanding of earth surface processes, but often treats the biosphere and physical world as uncoupled entities. This selection therefore also provides samples of work that point to an ongoing but significant disciplinary reappraisal in which it is the interactions between ecological and geomorphological realms that are of primary interest.
Thesis (Ph. D.)--University of Chicago. Bibliography: p. 116-119.
Fluvial processes and vegetation — glimpses of the past, present, and future Dynamic interactions of life and its landscape: feedbacks at the interface of geomorphology and ecology
- W R Osterkamp
- C R Hupp
- L Reinhardt
- D Jerolmack
- B J Cardinale
- V Vanacker
- J Wright
Osterkamp, W.R., Hupp, C.R., 2010. Fluvial processes and vegetation — glimpses of the past, present, and future. Geomorphology 116, 274–285. doi:10.1016/j.geo-morph.2009.11.018. Reinhardt, L., Jerolmack, D., Cardinale, B.J., Vanacker, V., Wright, J., 2010. Dynamic interactions of life and its landscape: feedbacks at the interface of geomorphology and ecology. Earth Surface Processes and Landforms 35 (1), 78–101. doi:10.1002/ esp. 1912.
Special issue: riverine hydroecology: advances in research and applications
- D Gilvear
- N Willby
- P Kemp
- A Large
Gilvear, D., Willby, N., Kemp, P., Large, A., 2008. Special issue: riverine hydroecology: advances in research and applications. Selected papers from the Tenth Interna-tional Symposium on Regulated Streams, Stirling, August 2006. River Research and Applications 24 (5), 473–475. doi:10.1002/rra.1126.
National Research Council Report (USA) — A Frontier in Earth Surface Processes: Dynamic Interactions of Life and its Landscape, MYRES (Meeting of Young Researchers in Earth Sciences) III Conference Delegates
- D Jerolmack
Jerolmack, D., 2008. National Research Council Report (USA) — A Frontier in Earth Surface Processes: Dynamic Interactions of Life and its Landscape, MYRES (Meeting of Young Researchers in Earth Sciences) III Conference Delegates. Submitted to National Research Council.
- W R Osterkamp
- C R Hupp
Osterkamp, W.R., Hupp, C.R., 1996. Preface. Geomorphology 14 (4), 275-275.
doi:10.1016/0169-555X(96)90005-7.
Landscapes on the Edge: New Horizons for Research on Earth's Surface
- Research National
- Council
National Research Council, 2010. Landscapes on the Edge: New Horizons for Research
on Earth's Surface. National Academies Press. 180 pp.