Biota affect hydrology, sediment transport, weathering and soil formation over variable temporal and spatial scales and thereby influence, hillslope, fluvial, coastal, and aeolian landscape form and dynamics. In turn, geomorphological and hydrological processes have large impacts on ecological processes by shaping topography and affecting water availability, which determines biological diversity and succession. Despite some advances, the conceptualisation and quantification of the processes, rates and feedbacks between geomorphology, hydrology and ecology are still limited.

Understanding these feedbacks between biological, hydrological and geomorphological processes is becoming increasingly important as new ‘building with nature’ projects emerge and also increasingly find their way into management (i.e. restoration projects). Physical, chemical and biological processes are in a constant state of flux, vary across both temporal and spatial scales and are regulated or enhanced by anthropogenic activities. Understanding of the biogeomorphological and ecohydrological effects of anthropogenic activities/ approaches and their wider socio-economic implications, remains largely rudimentary particularly in systems that are sensitive to human-induced or natural environmental change (e.g. high-mountain and polar environments, deserts, hillslopes, rivers and wetlands, salt marshes and deltas). As a result, there is a need to develop understanding around i) the magnitude and temporal persistence of anthropogenic stressors and their effects, ii) ecosystem resilience to anthropogenic stressors (including critical transitions in ecosystem state), and iii) new sustainable approaches to catchment management, such as utilization of ecosystem engineers for habitat improvements.

This session seeks contributions that are investigating biogeomorphologic interactions across all spatial and temporal scales, including experimental, field and computational/numerical modelling studies. We especially encourage interdisciplinary studies on river, and delta biogeomorphology, animal influences on geomorphic processes, chronologies of biogeomorphological change, and hillslope processes. Emphasis will be given to novel research on biogeomorphological feedbacks, on the quantification of feedbacks and associated rates, the linkage between terrestrial and aquatic environments, and the investigation of the resilience of coupled eco-hydro-geomorphic systems to human impact and climate change.

Public information:
We are happy to have two keynote speakers this year, one for fluvial biogeomorphology with Borbála Hortobágyi presenting on riparian plant response and effect traits on alluvial bars and one for coastal biogeomorphology with Olivier Gourgue presenting a new bio-geomorphic model approach accounting for subgrid-scale heterogeneity of biogenic structures.

Water is the defining feature of the habitable Earth; it is essential for all life as we know it. Evolution and maintenance of life in extremely water limited environments, which cover significant portions of the Earth, is not well understood. Akin to life, water-driven processes leave unique marks on the Earth’s surface. Mars is the only other planet currently known to bear the marks of water-driven surface processes, albeit fossil and of great age. The slow biotic and abiotic surface processes that may operate even in the virtual absence of liquid water are still essentially unknown. What is evident is that transient episodes of increased water availability can leave long lasting traces in extremely water limited environments. Intriguingly, those traces of bursts in Earth surface evolution have rarely been related to bursts in biological colonization/evolution, and vice versa, although both relate to the same trigger: water.

The objective of this session is to showcase research on the mutual evolutionary relationships between Earth surface processes and biota in arid to hyper-arid systems, where both biota and Earth surface process are severely and predominantly limited by the availability of water (rather than by extreme temperatures).
Solicited topics include (not exhaustive):
• fingerprints of biological activity at the (water) limit of the habitable Earth
• surface processes operating in the (virtual) absence of liquid water on Earth or extraterrestrial analogues (e.g. Mars)
• thresholds for biological colonization and concurrent fluvial transformation of landscapes
• tipping point(s) of biotically and abiotically controlled Earth surface systems
• chronometric and spatial information on the colonization and radiation of biota
terrestrial climatic records of (hyper-) arid regions on Earth

Arid to sub-humid regions contribute ca. 40 % to the global land surface and are home of more than 40 % of the world’s population. During prehistoric times many important cultures had developed in these regions. Due to the high sensitivity of dryland areas even to small-scale environmental changes and anthropogenic activities, ongoing geomorphological processes but also the Late Quaternary palaeoenvironmental evolution as recorded in sediment archives are becoming increasingly relevant for geomorphological, palaeoenvironmental and geoarchaeological research. Dryland research is also boosted by methodological advances, and especially by emerging linkages with other climatic and geomorphic systems that allow using dryland areas as indicator-regions of global environmental change.
This session aims to pool contributions from the broad field of earth sciences that deal with geomorphological processes and different types of sediment archives in dryland areas (dunes, loess, slope deposits, fluvial sediments, alluvial fans, lake and playa sediments, desert pavements, soils, paleosols etc.) at different spatial and temporal scales. Besides case studies from individual regions and archives, methodical and conceptual contributions, e.g. dealing with the special role of eolian, fluvial, gravitational and biological processes in dryland environments, their preservation over time in the sedimentary records, and emerging opportunities and limitations to resolve past and current dynamics, are especially welcome in this session.

In recent years there has been a growing emergence of interdisciplinary research areas concerned with investigating the dynamic and multifaceted interactions between biotic and abiotic components of aquatic ecosystems. Such is the acknowledged importance of these interactions, that quantifying and understanding the two-way feedbacks of interacting abiotic and biotic components is recognised as a key contemporary research challenge. However, the different terminology used by various disciplines highlights the separation rather than the overlap between disciplines. Further, in many instances the creation of new sub-disciplines (or research areas) is not developing the study field, but arguably is leading to the ‘reinvention of the wheel’ in parallel disciplines. Changing the traditional perspectives by bridging the gaps between disciplines is therefore key to bring considerable advances in aquatic research.
This session focuses on bringing together scientists from different backgrounds dealing with the effects of environmental (both biotic and abiotic) stressors on the aquatic biosphere, from individual organisms through to whole ecosystems with the aim of simulating truly interdisciplinary research. Several temporal scales ranging from a single event (e.g. response to hydropeaking, predatory attacks) to long term evolution (e.g. adaptation to climate change, ecosystem modification) may be considered. We expect strong contributions from researchers transcending a variety of disciplines such as geomorphology, engineering, ecology and environmental sciences. Emphasis is given to studies dealing with stressors driven by climate change or anthropogenic activities. In this context we particularly welcome contributions on consolidated or novel measurement techniques and modelling tools to assess the effects of environmental stressors (e.g. flow modifications, habitat alterations) on biota, such as vegetation, macroinvertebrates and fish, that cross disciplinary boundaries.

The session will include an invited keynote by Prof. Markus Holzner from ETH Zürich.

The Tibetan Plateau and surrounding mountain regions, known as the Third Pole, cover an area of > 5 million km2 and are considered to be the water tower of Asia. The Pan Third Pole expands on both the north-south and the east-west directions, going across the Tibetan Plateau, Pamir, Hindu Kush, Iran Plateau, Caucasian and Carpathian, and covering an area of about 20 million km2. Like the Arctic and Antarctica, the Pan Third Pole’s environment is extremely sensitive to global climate change. In recent years, scientists from around the globe have increased observational, remote sensing and numerical modeling research related to the Pan Third Pole in an effort to quantify and predict past, current and future scenarios. Co-sponsored by TPE (www.tpe.ac.cn), this session is dedicated to studies of Pan Third Pole atmosphere, cryosphere, hydrosphere, and biosphere and their interactions with global change. Related contributions are welcomed.

Ecosystems, their abiotic and biotic compartments as well as their internal processes and interactions can be interpreted as the result of numerous evolutionary steps during system development. Understanding ecosystem development can be regarded, therefore, as crucial for understanding ecosystem functioning. This session will highlight research in this field within two parts.

The first part of this session is dedicated to experimental approaches to disentangle these complex processes and interactions of the Critical Zone. Well-known flagship sites in this sense are, e.g., Biosphere2 in the USA or Hydrohill in China. In addition, post-mining landscapes worldwide offer multiple opportunities for establishing artificial experimental sites for various purposes. Many experimental sites are based on hydrological catchments as integrative landscape units. Other large-scale experiments focus on selected parts of ecosystems which were modified or transplanted. This part of the session tries to create a global overview on large-scale landscape experiments on ecohydrological, pedological, biogeochemical or ecological processes within the Critical Zone.

The second part is related to the co-evolution of spatial patterns of vegetation, soils and landforms. These patterns are recognized as sources of valuable information that can be used to infer the state and function of ecosystems. Complex interactions and feedbacks between climate, soils and biotic factors are involved in the development of landform-soil-vegetation patterns, and play an important role on the stability of landscapes. In addition, large shifts in the organization of vegetation and soils are associated with land degradation, frequently involving large changes in the functioning of landscapes. This part of the session will focus on ecogeomorphological and ecohydrological aspects of landscapes, conservation of soil resources, and the restoration of ecosystem functions.

Invited talks will be given by Dr. Abad Chabbi (Director of Research at the French National Institute for Agricultural Research, INRA) on “Challenges, insights and perspectives associated with combining observation and experimentation research infrastructure“. Part two of the session is proud to announce the invited talk of Prof. Praveen Kumar (Lovell Professor of Civil and Environmental Engineering, University of Illinois, USA, Director of the US NSF Critical Zone Observatory for Intensively Managed Landscapes) on "Co-evolution of landscape and carbon profile through depth: understanding the interplay between transport and biochemical dynamics".

Some of the major coastal disasters in the past decade have clearly demonstrated how nature has a primary role in reducing the impact of extreme coastal flooding events generated by storms, which produce a high cost to society as well as a threat to valuable ecosystems. After Typhoon Haiyan in the Philippines in 2014, the Government financed USD22 million for the restoration of mangroves along the affected coastlines as evidence grew showing that where coastal vegetation was present, this attenuated the magnitude of flooding. Similarly, following Hurricane Katrina the US government invested USD500 million for the restoration of coastal national parks and salt marshes, accepting the proofs that marshes helped to reduce the damage, in association with dike and levees. Thus, it is a prerequisite to propose that the reconstruction of ecosystems should be done before an event strikes, with a philosophy of prevention rather than a remedy, with a philosophy of recovery. In Europe too, many member states have started to promote the recreation of coastal wetlands, considering setback strategies as well as the reconstruction and vegetation of coastal dunes, which act as the first line of defence to flooding. As it is stated in the recently released EU-Science for Disaster Risk Management 2017 Report, a number of European Commission-funded demonstration projects are now supporting ecosystem-based Disaster Risk Reduction, to prove the added value of such an approach compared with traditional engineering solutions.

This new approach demands: the development of new tools to model and design these reconstructed environments; merging physical concepts like bed erosion and sediment transport with the parameterization of biologically-induced phenomena, such as the role of emerged and submerged vegetation in attenuating wave and current energy; as well as the role of plants in stabilising/destabilising the morphology of coastal dune systems.

The session welcomes contributions covering modelling and monitoring aspects, including innovative approaches in coastal morphological models that account for the presence of the ecosystems, quantifying feed-back interactions between the physical and biological components. We welcome case-studies reporting recovery of the ecosystems and of the physical environment following major extremes such as tropical and extra-tropical storms. We also welcome contributions on case studies documenting new techniques for revegetation of submerged as well as subaerial environments.