​Sylvain Kuppel is currently a postdoctoral Research Fellow in the Northern Rivers Institute at the University of Aberdeen (Scotland).

​What does ecohydrology mean to you?
I see ecohydrology as studying the reciprocal links between living organisms and terrestrial water pathways, with big questions such as: Where do organisms get their water? How do we tell? Where do humans come in the picture?

What are your undergraduate and graduate degrees in?
I have a B.A. in general engineering, a M.Sc. in physics, and a Ph.D. in Meteorology and Physical Oceanography of the Environment.

How did you arrive at working in/thinking about ecohydrology?
In a nutshell, it has been a story of trial and error! As a child I was soon interested in understanding the physical world around me, as well as concerned by how human societies could exist / develop without destroying it. However, I also had the problem of being fascinated many other topics and disciplines (scientific or not) without the ability to choose one in particular, even for a tentative undergraduate path...

Like quite a few other undecided high school students in France, I enrolled in the “classes préparatoires”, leading to an engineering school. During that time, I surely ingurgitated a lot of fundamental and applied Science there (except for life sciences, to my later regret), but without much time for hindsight or profound, critical thinking. Then I realized engineering was not my thing, but luckily there was a double degree program with universities in Japan, a culture I had been attracted to for a long time. Ten thousands of kilometers later, as a master student I started connecting some dots between plasma physics and my interest in “cleaner” energy production. While my routine back then was whispering me academic research could definitely be my kind of dream job, something remained nonetheless unsatisfying in how I could make my work directly connected to more ideological endeavors. This is why I then started a PhD in ecosystem modelling: if I could not help design a novel, sustainable energy production system, then I would dedicate myself to study this Nature I love so much!

From my background in physics, I always kept a tendency to think in terms of exchanges between systems, back then applied to how plant phenology drives the terrestrial carbon cycle. After this belated “eco” introduction, the “hydro” side really came with this crucial encounter with Esteban Jobbágy as a postdoc at the University of San Luis in Argentina. My interactions in his group and my work on analyzing flooding cycles made me realize how these extremes events could be related to land management practices (such as converting pastures to crops) and would in turn affect ecosystem functioning in entire landscapes. And I appreciated the diversity of approach I could take, from conceptual studies to addressing very applied societal problems. More than enough for me to find ecohydrology stimulating ever since!

What do you see as an important emerging area of ecohydrology?
I agree with the other “leaves” here that urban ecohydrology has a lot of potential to help addressing pressing issues given the increasing footprint of cities on the planet, and this field indeed seems to become a “hot” thing at the moment. I also think that emerging efforts in upscaling reasonably-known plant-water strategies at large spatial scales will help understanding how ecosystems organize and could interact with environmental change. That includes the eco-climatic teleconnections where patterns of atmospheric water circulation are key. Finally, I am enthusiastic to see the “eco” of ecohydrology gradually expanding from plants to integrating animals and fungi in the picture, as they can be active players in hydroecosystem functioning. Of course, as an emerging interdisciplinary field, many potential area of research remain to be unveiled!

Do you have a favorite ecohydrology paper?  Describe/explain.
They are quite a few I like, but one that quickly comes to my mind is ‘A method of determining rooting depth from a terrestrial biosphere model and its impacts on the global water and carbon cycle’ by Axel Kleidon and Martin Heimann, published in Global Change Biology in 1998. They inferred rooting depth using global meteorological datasets and applying an evolutionary principle: plants evolved to have an optimal root profile (i.e., that maximizes their productivity) given the local water resources (precipitation supply and evaporative demand). Not only it resulted in some consistent agreements with field-based studies, but applying this new “database” to a simple ecosystem model had a dramatic impact on estimating partitioning between evapotranspiration and runoff. In particular, their approach seemed to confirm the observation that deeper roots are needed to explain the observed sustained productivity in relatively wet regions with a dry season like parts of the Amazon basin. On a personal level, I reckon this neat paper passed on to me this idea of considering the short-term variations in the water balance (and not only annual budgets) when thinking about ecosystem behavior and water transfers in the landscape, as well as trying to use simple conceptual tools whenever possible!

What do you do for fun (apart from ecohydrology)?
Circus and dance both (literally) balance my daily life! My circus practice now focuses on corde lisse (also called aerial rope or free rope), mostly solo training and preparing performances, but I also love teaching it at the local circus centre. While I perform and sometimes choreograph for one-off dance projects (contemporary and physical theatre) as well, I just like moving in general, and Contact Improvisation is my favorite form of dancing: it’s amazingly playful, social, emotional and accessible to everyone. Finally, when I find time to escape the city I enjoy exploring the beautiful, peaceful landscapes of Scotland on a hike or a bike ride/tour, although recently it happened much less often then I’d like to admit!

Dr. Ashley Matheny is an Assistant Professor in the Department of Geological Sciences at University of Texas at Austin.

What does ecohydrology mean to you?
For me, ecohydrology is the study of how hydrology is influenced by ecosystems and in turn how ecosystems respond to the hydroclimate.
 
What are your undergraduate and graduate degrees in?
I have a bachelor of arts in Spanish and a bachelor of science in civil engineering with a focus on structural engineering. My master’s and my doctorate are both in civil engineering with a specialization in hydrologic engineering.
 
How did you arrive at working in/thinking about ecohydrology?
In short, through a series of very fortunate events. I stumbled into ecohydrology by chance to the extent that I often joke that I am the “accidental academic.” After graduating with my degree in structural engineering, I worked for the US Army Corps of Engineers (USACE) in Huntington, WV, where I was part of several projects involving levees, floodwalls, and locks and dams. But, I was also able to be part of numerous smaller projects focused on riverbank, wetland, and riparian forest restoration. Through my work with the USACE, I developed a love of hydrology and field work and decided to apply to get a master’s degree in hydrologic engineering. At that time, I didn’t realize that incoming graduate students generally contacted potential advisors to request to join a lab before applying. Luckily for me, I won a fellowship and was contacted by my eventual advisor, Gil Bohrer, who had a project he was looking for someone to tackle. I wasn’t sold on constructing sap flow sensors and studying forest responses to disturbance at first, but I figured it was only two years and it would be nice to try something new. At the end of the first year of my master’s, I had the opportunity to travel to Panama to collect ground-based LiDAR measurements of the rainforest canopy. It was such an exciting experience to conduct research with the Smithsonian on a tropical island that I didn’t think twice when Gil asked me to continue as a PhD student upon my return. There was a turning point for me in the course of graduate school where I realized, particularly when I was in the field, that work didn’t feel like work. This was the moment when I decided that I wanted research to be my career, rather than going back to the USACE or working as a consultant. I had aspirations of building a career as a research scientist in a national lab. However, shortly after I started my post-doc appointment, there was a political shift and a federal hiring freeze. At that point, Gil and I decided that I should start applying to a few faculty positions to see where I needed to devote time during my post-doc in order to be competitive in the job market. Fortunately, the Jackson School of Geological Sciences at the University of Texas at Austin made me an offer I couldn’t refuse, and I took the leap onto the tenure-track and started my own ecohydrology lab. Although it’s a long way removed from structural engineering, I’m happy to say that I have an amazing job and that I am motivated daily to continue exploring new and exciting avenues of ecohydrologic research.
 
What do you see as an important emerging area of ecohydrology?
To me, the most interesting aspect of ecohydrology is the dynamic regulation of transpiration by plants and the way ecosystem processes couple subsurface and atmospheric processes and feedback into weather and climate. As human populations expand and continue to change land use and land cover types, it will be fascinating to watch how this interacts with global climate change.
 
Do you have a favorite ecohydrology paper?  Describe/explain.
My favorite ecohydrology paper is Brooks, R.J., Barnard, H.R., Coulombe, R. and McDonnell, J.J., 2010. Ecohydrologic separation of water between trees and streams in a Mediterranean climate. Nat. Geosci., 3(2): 100-104. The authors used stable isotopes to analyze water being used by different species of tree during the dry season to identify the water source each was using to survive drought conditions. This work inspired me to think more broadly about the range of possible drought adaptations and hydraulic strategies employed by species that regularly co-exist in the same ecosystem but function radically differently. 
 
What do you do for fun (apart from ecohydrology)?
Outside of my field research, I like to be active, and I love to travel. I’m a bit of an adrenaline junky and enjoy wakeboarding, waterskiing, snow skiing, rock climbing, and dancing. In my free time I also enjoy painting and sewing.

Dr. Stan Schymanski is a Lead R&T Associate at the Luxembourg Institute of Science and Technology (LIST), where he holds an ATTRACT fellowship from the Luxembourg National Research Fund (FNR) to investigate "Water and Vegetation in a Changing Environment". 

What does ecohydrology mean to you?
My definition of Ecohydrology is that of a discipline that concerns all ecological processes that are relevant for Hydrology and water resources, and investigates their effect on hydrological processes and vice versa. An important example is the effect of vegetation processes on transpiration rates and water resources, but I would also include effects of e.g. earth burrowing organisms on soil water retention and drainage properties. I like to distinguish Ecohydrology from Hydro-ecology, which I would define as a sub-discipline of Ecology that focuses on the effect of hydrological processes on  freshwater ecosystems.

What are your undergraduate and graduate degrees in?
My undergraduate degree is in Geobotany from the University of Freiburg in Germany. I did my PhD in Environmental Engineering at the University of Western Australia.

How did you arrive at working in/thinking about ecohydrology?
I always loved plants, water and the outdoors. For my undergrad thesis in Geobotany, I did a lot of field work on Middle European peat bogs, trying to understand if their decay had to do with facilitated drainage due to historical peat removal  and drainage channels. My supervisors, Dr. Arno Bogenrieder and Dr. Pascal von Sengbusch, hypothesised that in a peat bog, initial drainage can stimulate tree growth and therefore water extraction, leading to a positive feedback between decreasing water tables and further enhancing tree water use. This motivated me to learn more about vegetation-hydrology feedbacks.

I started off my post-graduate path at a forestry research institute (FVA), investigating the flood tolerance of the common ash in Southern Germany. At the same time, I met my wife Emma, who was on exchange from Australia to do her undergraduate thesis in Freiburg. When she returned to Australia, I revived my interest to go abroad for a PhD project and extended my search to Australia. As it turned out, one of Emma's professors at the University of Western Australia, Dr. Sivapalan, was looking for a PhD student to investigate Eagleson's Ecological Optimality hypotheses. A few more lucky coincidences brought me to Perth on an international scholarship and support by the CRC for Greenhouse Accounting, which gave me the opportunity to learn about hydrology from Siva and about ecology from my external advisor, Dr. Michael Roderick and colleagues at the Australian National University. This inspiring mentoring team was complemented by generous support from Dr. Lindsay Hutley from Charles Darwin University and Dr. Jason Beringer, then from Monash University, who taught me about the intricacies of tropical savannas and shared their eddy covariance measurements with me.

I found the transfer from a then rather descriptive discipline (Geobotany) to a very quantitative discipline (Environmental Engineering/Hydrology) very challenging and stimulating at the same time. I found out that my naive questions about hydrology sometimes inspired hydrologists as much as their seemingly naive questions about plants inspired me to dig deeper and question my intuitive understanding of the underlying processes. At the same time, Mike Roderick exposed me to a very quantitative view of plant ecophysiology and ecology, while Jason Beringer and Lindsay Hutley kept us all close to the ground using their detailed site-specific knowledge. Since then, I have been exploring the boundaries of Ecohydrology, by venturing into thermodynamics and environmental physics and extending my tool set by lab experiments and open science approaches.

If I had to summarize everything I learned during that time in one point, it would be that in order to understand the vegetation and catchment response to environmental forcing, we need to understand the hydrological system, the physics of vegetation-environment interactions and the ecology determining vegetation dynamics. This inseparability of Ecology and Hydrology in water-limited systems is to me the main pillar of of Ecohydrology.
 
What do you see as an important emerging area of ecohydrology?
Environmental change, such as increasing atmospheric CO2 concentrations, changing climate patterns and increasing nitrogen deposition can have a strong indirect effect on water resources by their direct effect on vegetation. We are only at the beginning of understanding how vegetation responds to these environmental changes at different spatial (leaf-individual-ecosystem) and temporal (seasonal, annual, decadal, centennial) scales. With new sensing techniques, both at the macro (satellites) and micro-scale (distributed networks of micro-sensors, high-resolution and high-frequency sampling etc.), we will be able to test more details of our understanding and formulate new, more relevant questions about hydro-ecosystem functioning. This testing of our understanding will also benefit from improved modelling capabilities, linked to freely available, open-science community models permitting to test one component at a time and the effect of feedbacks between different domains (soil-vegetation-atmosphere, groundwater-soil moisture-surface water etc).

Do you have a favorite ecohydrology paper?  Describe/explain.
My favorite paper is:
Cowan, I. R. and Farquhar, G. D.: Stomatal Function in Relation to Leaf Metabolism and Environment, in: Integration of activity in the higher plant, edited by D. H. Jennings, pp. 471–505, Cambridge University Press, Cambridge, 1977

In this paper, Cowan and Farquhar link leaf transpiration to photosynthesis, arguing that plants tend to maximise photosynthetic carbon uptake per unit of water lost. This enables predictions of stomatal dynamics and transpiration at the diurnal scale, essentially linking vegetation water use to atmospheric CO2 concentrations, a link that is missing in many hydrology-originated approaches to ecohydrology. They also discuss the necessity for day-to-day water use optimisation in the context that water used early on in a dry period may be lacking towards the end of the dry period, essentially linking plant water use to water resources from a purely ecological perspective. The paper also demonstrates the benefits of interdisciplinarity, as Cowan and Farquhar use a concept from economy to derive a solution to the ecological optimisation problem.

What do you do for fun (apart from ecohydrology)?
I love spending time in nature with my wife and my son, either hiking, paddling, mountain biking or skiing. I also enjoy more dangerous endeavors with friends, such as whitewater kayaking, backcountry skiing or trail biking. I  played international level ultimate frisbee for many years, which I like for its emphasis on team spirit, fair play and hard work.

Khandker Ishtiaq is currently working as a post-doctoral research associate in the Ecological and Water Resources Engineering Lab at West Virginia University, Morgantown. | Twitter: @ksishtiaq 

Francina Dominguez is a Hydroclimatologist and Associate Professor in the Department of Atmospheric Sciences at the University of Illinois.

What does ecohydrology mean to you?
As a hydroclimatologist, I see ecohydrology through the lens of land-atmosphere interactions. My focus is on understanding how ecosystems mediate the transfer of water/energy/momentum from the surface and subsurface to the overlying atmosphere. I mainly see these interactions at the very large scales (regional to continental).

What are your undergraduate and graduate degrees in?
My undergraduate and graduate degrees are in Civil and Environmental Engineering. I did a Postdoc in Hydrology and have been faculty in Atmospheric Sciences since 2009.

How did you arrive at working in/thinking about ecohydrology?
My PhD thesis focused on precipitation recycling, or the contribution of evapotranspiration within a region to its own precipitation. Ecosystems play a critical role in this, because through transpiration plants affect the time and spatial scale of precipitation recycling. I have been thinking of the role of ecosystems on the overlying atmosphere ever since. Now I have broadened my focus, and in addition to precipitation recycling I try to understand how ecosystem variability affects the overlying atmosphere by changing the thermodynamics and dynamics of the atmospheric system - from the local to the global scale.

What do you see as an important emerging area of ecohydrology?
The impacts of land-use and land-cover change on the hydroclimate of a region (from the subsurface to the atmosphere). I know this is really not a new area, but I don’t think we have really answered this question.

Do you have a favorite ecohydrology paper?  Describe/explain.
My new favorite paper is: “Hydrologic regulation of plant rooting depth” in PNAS by Fan et al. 2017. This paper lays out a new paradigm for plant rooting depth based on soil moisture availability from both precipitation and groundwater. It provides a global map of plant rooting depth, based on both observations and numerical modeling. I am a big fan of the work of this group!

What do you do for fun (apart from ecohydrology)?
I dance! I used to be a contemporary dancer. Now, I don’t belong to a dance group, but I dance with my two girls all the time. 

Elizabeth Boyer is an Associate Professor of Water Resources in the Department of Ecosystem Science and Management at Penn State University.  Twitter: @bethboyerPSU

What does ecohydrology mean to you?
Ecohydrology encompasses ideas and processes at the interface between hydrology and ecosystem ecology, and effects of biotic processes on the water cycle.
 
What are your degrees in?
I have a B.S. degree in Geography from Penn State University focused on remote sensing and geographic information systems; and M.S. and Ph.D. degrees in Environmental Sciences from the University of Virginia focused on hydrology.  I completed a post-doc in the Department of Ecology and Evolutionary Biology at Cornell University focused on biogeochemistry. 
 
How did you arrive at working in/thinking about ecohydrology?
When I was an undergraduate, I had the opportunity to work as a trainee via an internship at Battelle / Pacific Northwest National Laboratory.  I was interested in pursuing a career in remote sensing at the time, but some great mentors there sparked my interest in surface and ground water.  That internship got me excited about quantifying processes in nature and concepts like fractal scaling, and led directly to my graduate and postdoctoral work in hydrology.  My research has since focused on understanding and predicting water quality, where you need to represent coupled hydrological, ecological, and geochemical processes in order to get it right.
 
What do you see as an important emerging area of ecohydrology?
I’m interested in how changes to eco-hydrologic systems – stemming from multiple stressors such as land use change, climate change, invasive species, and atmospheric deposition – will impact water quality and water scarcity.  Many parts of the world already lack clean water, many landscapes are being degraded, and many surface and ground waters are being polluted.  Water scarcity will be an even greater problem in the coming years as demand for water increases with population and economic growth.  Concepts and tools from ecohydrology can help achieve sustainable management of water, and to help solve global water problems.
 
Do you have a favorite ecohydrology paper?  Describe/explain.
Maciej Zalewski’s papers and reports have provided many ideas for my work, like his 2002 paper in Hydrological Sciences Journal on “Ecohydrology: the use of ecological and hydrological processes for sustainable management of water resources.”  Zalewski was ahead of the times in promoting the role of ecosystem services in integrated watershed management.  He articulates using ecosystem properties as a management tool to amplify opportunities and to eliminate threats – such as reducing point and non-point pollutants and mitigating catastrophic floods and droughts. I recommend that everyone read his stuff!
 
What do you do for fun (apart from ecohydrology)?
I love spending time with my family and friends exploring nature, especially in the forests, gorges, and lakes around Ithaca, NY.  In an earlier phase of life I was into photography, and I still like capturing light, color, and adventures through pictures.

.Jeremy Littell is a Research Ecologist / Lead Scientist  (Climate Impacts) with the US Geological Survey and Alaska Climate Adaptation Science Center.

Diego Riveros-Iregui is currently an Assistant Professor in the Department of Geography at the University of North Carolina at Chapel Hill.  He is also the Deputy Chair of the AGU Ecohydrology Technical Committee.  Web: http://diegori.web.unc.edu/ | Twitter:  @carbonshed

What does ecohydrology mean to you?
Ecohydrology is the intersection of all the fields that I have always been intrigued by: geology, hydrology, ecology, climate science, and even humans – all interacting over time.

What are your undergraduate and graduate degrees in?
I have a B.S. in geology from the National University of Colombia, an M.S. in geology and geophysics from the University of Minnesota, and a Ph.D. in ecology and environmental sciences from Montana State University.

How did you arrive at working in/thinking about ecohydrology?
I never spent much time thinking about living organisms during my undergrad. In fact, most of my time as an undergrad I spent looking at metamorphic rocks under a microscope. But during my master’s I worked on a hydrogeology project that had a component on surface water – groundwater exchange, and the surface water body involved was a fairly big wetland that did all sorts of great things to the chemistry of the waters I was collecting. Thus, I became very interested in the carbon cycle and decided that if I ever did a Ph.D., the project would have to couple the water and the carbon cycles. That’s how I found - in an EOS ad! - an announcement for a Ph.D. position in Montana, working at the intersection of hydrology and ecology in subalpine forests. I was so fascinated by the ‘eco’ aspect of the project that after my Ph.D., I decided to do a post-doc in an ecology lab in the Department of Ecology and Evolutionary Biology at the University of Colorado in Boulder.

What do you see as an important emerging area of ecohydrology?
There are so many! Ecohydrology conveys interdisciplinary knowledge that is required to address current and future environmental challenges in response to global change. Water is fundamental for biological processes, ecosystem function, and for the coupling of processes on or below the land surface and in the atmosphere. I think ecohydrologists are in a strong position to tackle many of the challenges that humanity faces today, including sustainability of ecosystem services and feeding the world at 9 million.
 
Do you have a favorite ecohydrology paper?  Describe/explain.
Again, there are so many! But I would put Bruijnzeel and Veneklaas (1998) among some of my favorite papers. It was published in Ecology, and it describes productivity of tropical montane cloud forests, involving complex terrain, soil moisture, fog, limited solar radiation (due to high cloudiness), low nutrients, and poor soil conditions. Despite all of this, these ecosystems have evolved to become some of the most biodiverse on Earth and to date they remain very much understudied.

Bruijnzeel LA, Veneklaas EJ (1998) Climatic conditions and tropical, montane forest productivity: the fog has not lifted yet. Ecology 79:3–9.

What do you do for fun (apart from ecohydrology)?
I have a five-year-old and a one-year-old that keep me pretty busy, so any time outside work revolves around my wife and daughters. We spend a lot of time outside, hiking in the woods, riding bicycles, or doing family stuff. Our weekends are usually booked with activities from birthday parties to soccer practice to trips to the museum. I enjoy distance running, traveling, and cooking. I also try to combine exercise with family time. I once ran a half marathon pushing my then 30-lb daughter in her stroller – it was hard and fun!  

Elizabeth (Liz) Agee is currently a PhD candidate with Dr. Valeriy Ivanov in the Department of Civil and Environmental Engineering at the University of Michigan - Ann Arbor.   Twitter:  @thisisnotliz 

​Bhavna Arora is a Research Scientist in the Earth and Environmental Sciences Area at Lawrence Berkeley National Laboratory. She currently serves as the lead for the Biogeochemical Cycling Group within the Energy Geosciences Division.