Dr. Jia Hu is an Assistant Professor in the School of Natural Resources and Environment at the University of Arizona.

What does ecohydrology mean to you?
Ecohydrology is a field of research that links hydrological and ecological processes by studying the feedbacks that occur between both components. I am completely biased, but I do believe that some of the most exciting hydrology related research is currently related to ecohydrology.

What are your undergraduate and graduate degrees in?
My undergraduate degree was in Integrative Biology from UC Berkeley.
Graduate degree was in Ecology and Evolutionary Biology from CU Boulder.

How did you arrive at working in/thinking about ecohydrology?
My undergraduate and graduate research interests were mainly focused on plant water and carbon relations. However, as I began collaborating more with watershed hydrologists, I realized how important it was to take a broader, landscape perspective. By focusing primarily on plant water cycling, I had been completely ignoring how water got to the plants in the first place. By recognizing that soil, plant, and atmospheric water cycling were inextricably linked, I began to take a more holistic approach to research and begin to ask more exciting questions.

What do you see as an important emerging area of ecohydrology?
Because I come from a background in ecology, I may view ecohydrology differently than most ‘ecohydrologists.’ The discipline of ecohydrology arose from hydrology, and I would argue that a more accurate description of the field in its current state is ‘hydrological-ecology,’ since hydrology is still very much the main focus. However, the field is rapidly changing and the integration of both hydrologic and ecologic processes is becoming more common.

One of the most exciting areas are research in ecohydrology is our ability to begin describing mechanisms that govern how water moves through complex landscapes (e.g. mountain watersheds), and the subsequent response by vegetation once water becomes available. By moving beyond simply describing patterns of water availability and water use, but testing mechanisms on why water moves or how it is used in a particular way, the field of ecohydrology can truly begin to integrate both disciplines.

Do you have a favorite ecohydrology paper?  Describe/explain.
Most of us are taught that water typically moves from the soil, to the roots, and then to the atmosphere (i.e. SPAC); however, it is becoming increasingly common to find studies that show direct uptake of water from the leaves and the subsequent downward movement of water into trunks of trees. This mainly occurs in foggy or cloudy environments, where cloud water or fog can be a critical moisture source. This ‘wicking’ of occult precipitation from the atmosphere is not only important in regulating plant water status, but it can also being an important moisture source in stream and even ground water (e.g. cloud water input, fog drip, etc.). Thus, my favorite ecohydrology ‘paper’ is not a paper, but a book, titled, ‘Tropical Montane Cloud Forests: Science for Conservation and Management,’ Eds. Bruijnzeel, Scatena, and Hamilton. While the scope of this book is about cloud forests, the perspective that fog and cloud water can be important sources of moisture is quite important. Furthermore, if we begin to lose vegetation from these tropical cloud forests, from either deforestation or ‘cloud-lifting,’ then there may be less precipitation inputs into tropical headwater ecosystems, leading to less streamflow in the lowland tropics, particularly during the dry season. These feedbacks between vegetation and hydrology are tightly coupled in these systems, and offers exciting opportunities for research!
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What do you do for fun (apart from ecohydrology)?
I love being outdoors and working in the field is one of my favorite things to do. When I lived in Boulder, CO and Bozeman, MT, skiing and hiking were my two favorite activities. Now that I live in Tucson, I am trying to take advantage of being able to hike 365 days of the year. I have two kids who are now finally big enough to hike longer distances on their own and it is my goal to explore more of AZ this year. At home, I love to cook, and spending hours on Sunday afternoon cooking a big family meal is a perfect way to wrap up the weekend.

Dr. Amilcare Porporato is the Thomas J. Wu ’94 Professor of Civil and Environmental Engineering and Princeton Environmental Institute at Princeton University.

Aurora Kagawa-Viviani is currently a PhD candidate with Thomas Giambelluca in the Department of Geography and Environment at the University of Hawaiʻi at Mānoa. 

​Dr. Paulo Tarso S. Oliveira is a Professor of Hydrology and Water Resources at the Federal University of Mato Grosso do Sul (UFMS), Brazil. 

What does ecohydrology mean to you?
In my vision, ecohydrology is a way to better understand the environmental systems dynamics, where hydrological and ecological processes are investigated by an interdisciplinary and integrated approaches. Water is the link between such processes, in which hydrological processes influence and provide feedbacks on the aquatic and terrestrial ecosystem dynamics and vice versa. Furthermore, human activities have altered the ecosystems and water fluxes; therefore, a better comprehend of ecohydrology is crucial to help us to keep a balance between the water-related uses and consequently the human life.
 
What are your undergraduate and graduate degrees in?
I was born in Brazil in 1985 and received both my BSc degree in Environmental Engineering (2009) and MSc degrees in Water Resources (2011) at the Federal University of Mato Grosso do Sul (UFMS), Campo Grande - MS, Brazil.
My Ph.D. in Science - Hydraulics and Sanitary Engineering was obtained in 2014 at the University of São Paulo (USP), São Carlos - SP, Brazil. I also worked as a visiting researcher (2013-2014) at the United States Department of Agriculture (USDA-SWRC) and at the University of Arizona, Tucson, AZ, USA.
 
How did you arrive at working in/thinking about ecohydrology?
When I was a child, I usually spent all holidays on my grandfather’s farm. In the back of the farm’s house there is a stream that for several years was used to generate energy (small-scale hydropower) and where my dad and uncles learned to swim. However, the small-scale hydropower stopped working and I could not swim in this stream because the streamflow was too low, the sediment transport compromised the water channel, and the water quality was not good. Thus, like as any child I asked several questions for my dad, such as: Why can’t I swim? What is going on with the water? Why is the stream too shallow? This has never left my mind!! During my PhD I could study and respond to all of these questions, and I can say I did it studying ecohydrology. One of the main goals of my thesis was to obtain a better understanding of the mechanisms of hydrological and soil erosion processes approaching aspects of the relationship among hydrology, human activities, and the environment. To achieve that, I worked with different scales (plots, watershed and continental) and data sources (experimental field, laboratory, and remote sensing).
 
What do you see as an important emerging area of ecohydrology?
I consider an important emerging area is to better understand ecohydrological processes, and its response to changes, in different spatial-temporal scales. For instance, in a recent study we found a water provisioning improvement in a tropical watershed through payment for ecosystem services based on soil and water conservation practices and vegetation recovery. However, we need to know if the same approach can work in a similar way for different spatial scales (local-regional-continental), climate, and vegetation conditions.

In addition, more investigations are needed considering a catchment coevolution approach, where we can investigate how climate, soils, vegetation, and topography have coevolved during the past and how they might do so in the future. This approach is important to explain catchment's features and functions, and to evaluate the most vulnerable and resilient catchments considering global or regional changes.

Another emerging area that I can point out is an ecohydrological approach with solutions to guarantee the food-energy-water-ecosystem security. It is motived because global population have grown and changed the standards of living promoting an increase of the demand for clean water, food, and energy to unprecedented levels. In addition, we have grappled each year across the globe with the climate change effects, mainly longer-term droughts and more-intense floods. Therefore, new insight in ecohydrology will be needed toward a better solution for these challenges.
 
Do you have a favorite ecohydrology paper?  Describe/explain.
It’s really hard to pick just one. I can cite important ecohydrology papers for me, such as: Rodriguez‐Iturbe (2000), Rodriguez‐Iturbe et al (2009); Newman et al (2006), among others. However, I would like to highlight here the papers by Orellana et al (2012) and Troch et al. (2013). The first one, is a great review paper providing the state of knowledge on groundwater‐dependent vegetation. This paper helped me to understand how groundwater levels might determine vegetation composition/density or vice versa. The second one, shows a strong interaction between climate, vegetation and soil properties that lead to specific hydrologic partitioning at the catchment scale. I like this paper because it helps us summarize different catchment features in a simple and predictable outcome of hydrological partitioning. This paper is really useful to understand past and future catchment coevolution and it is a theme that I currently study.
 
What do you do for fun (apart from ecohydrology)?
It is a good question; I can say that it has been changed during my life. Some years ago, I could say that it is working out, running, swimming, playing soccer, or any other sport... However, currently with two little daughters (Marina: 2 years and half; Milena: 23 days) my life is much busier, but sweeter and fun.  Now , I spend my free time with my wife and daughters doing kids things, e.g. playing dolls, swimming sometimes (Brazil is really hot), and visiting parks or playgrounds!

Dr. Pamela Nagler is a Research Physical Scientist with the USGS Southwest Biological Science Center. She resides in Tucson, AZ. 

Dr. Kim Van Meter is transitioning from a post doc position at University of Water Loo to an Assistant Professor position at the University of Illinois at Chicago in January 2019.    Twitter: @VanmeterKVM

What does ecohydrology mean to you?
For me, ecohydrology is about seeing the connections between systems.  The intersecting disciplines of ecology and hydrology are, of course, built into the word “ecohydrology.” As the field has grown, however, there have been further crossovers and synergies to include a range of different domains, from geochemistry to economics and sociology. To study ecohydrology is to study feedbacks between systems, the impacts of hydrology on ecosystems, of ecosystems on hydrology.  As an ecohydrologist, I ask questions about how humans interact with water and the environment, and how water systems and ecosystems coevolve with human systems.
 
What are your undergraduate and graduate degrees in?
My educational background has been a winding road!  My undergraduate degree was in Literature.  I have two master’s degrees, one in Organic Chemistry and another in Environmental Engineering.  My Ph.D. is in Earth and Environmental Sciences.
 
How did you arrive at working in/thinking about ecohydrology?
I came to my interest in water and water quality from a very practical perspective.  I was traveling in Haiti, where I adopted my son, and was devastated by the death of two young babies at my son’s orphanage due to contaminated water.  I became determined at that time to build a career that expanded beyond the lab to include larger interactions between science and the environment, between human and natural systems. From that point, my interests and my research grew to encompass a range of questions about human impacts on water quality and about feedbacks between water quality and ecosystem health. I think that these kinds of questions and concerns place me squarely in the middle of the new and growing science of ecohydrology.
 
What do you see as an important emerging area of ecohydrology?
I see urban ecohydrology as an exciting new frontier.  Cities in the 21st century are growing quickly—it has been predicted that by 2050 approximately 65% of the developing world and 85% of the developed world will be living in urban areas. As noted by Diane Pataki, urban settlements are one of the few ecosystems on earth that are actually increasing in extent. Accordingly, there are range of important research questions for the urban ecohydrologist. I am particularly interested in the ways in which cities alter both regional and global-scale nutrient cycling. As the built environment increases in extent, it will be crucial to understand how cities mediate the flow of water, nutrients, and a range of contaminants across the urban/suburban/rural continuum.
 
Do you have a favorite ecohydrology paper?  Describe/explain.
Although it’s difficult to pick a favorite paper, one that has been influential in my thinking is a 2014 paper led by Peter Groffman on the “Ecological homogenization of Urban USA.” 
In the paper, the authors explore the urban “homogenization” hypothesis. In other words, they ask the question, does urban land use exert a homogenizing effect across urban areas? Is a Phoenix lawn more similar to a Baltimore or a Minneapolis lawn than to the Sonoran Desert ecosystem surrounding the city.? The findings of their work are important, as they suggest that while decisions about things as seemingly trivial as suburban lawn management may be individual decisions, they are actually tied to broader forces, from social structures and socioeconomic status to national-scale marketing.  Because human behavior, like the biophysical behavior of natural systems, is strongly shaped by a panoply of broader forces, we are able to develop a theory and science of human habitats. From this point, we can move forward to understanding complex feedbacks between cities, water, and ecosystems.
 
What do you do for fun (apart from ecohydrology)?
My dog Darcy (named after the Darcy equation, of course) is a great source of fun and entertainment.  I’ve also recently become obsessed with escape rooms.

​Dr. Daniele Penna is an Associate Professor at the University of Florence (Italy).
www.danielepenna.co.nf

What does ecohydrology mean to you?
As others in this blog have reported, ecohydrology is strictly associated to the broad concept of “interaction” between water-related processes and the biotic component of the ecosystems. I’m currently teaching a graduate course in “Hydrology of the Wildlife Systems”, basically a combination of stream ecology and ecohydrology: I have not done any statistics but I can easily realize that the words I tell most often to the students are “water”, “ecosystems” and “interaction”, and I’m trying to stimulate them to achieve a wide thinking and a far-reaching view on how the different components in the environment are closely linked and influencing each other. To me, ecohydrology means studying the functional interrelations between water and vegetation in the critical zone, with a particular focus on forested catchments and agricultural areas. I’m particularly interested in how plants (trees but not only) affect the hydrological cycle and the hydrological processes at the catchment scale, and vice-versa, and how human inputs in anthropic settings (e.g, irrigation) influence tree response and sources of water uptake which in turn play a role on water stored in soil and in shallow groundwater.
 
What are your undergraduate and graduate degrees in?
I have a B.S. and M.S. in Natural Sciences from the University of Milan (Italy), with a thesis based on a phytosociological (and partially geomorphological) analysis of spruce population dynamics in an Alpine valley. So, trees were my first love. I then moved to the University of Padua (Italy) where I obtained a one-year degree on Hydrological and Geological Hazard Assessment and Mitigation followed by another M.S. in Forest and Environmental Sciences.
I have a PhD in Management of Water Resources from the same university: I pushed vegetation dynamics aside for a while and started to work on spatial and temporal patterns of soil moisture in a beautiful mountain catchment in the Italian Dolomites, under the supervision of prof. Marco Borga.
 
How did you arrive at working in/thinking about ecohydrology?
During my PhD I was trained as an experimental catchment hydrologist, and I began using environmental tracers to study catchment- and hillslope-scale runoff generation processes. I did not forget my background on trees but I tended to see precipitation, meltwater, stream water and subsurface water as the only fundamental elements of any catchment, while (evapo)transpiration was somehow a “resulting” process. Then, the rapid development of laser spectroscopy for the determination of stable isotope ratios in water, easier to operate and more affordable compared to traditional mass spectrometry, combined with a growing interest of the scientific community towards isotope-based analysis of tree water uptake pushed me to start investigating the spatial and temporal variability of water sources accessed by trees in forest and agricultural settings. These efforts are leading me to learn more, expand my knowledge and obtain a broader, more comprehensive and exciting perspective on the ecohydrological relations between vegetation and the other components of the water cycle in the critical zone.
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What do you see as an important emerging area of ecohydrology?
Although it should be implicit in the concept of ecohydrology, I think that increasing the interdisciplinary approach is a critical step to further advance ecohydrological studies. I have the feeling that quite often, at least in my experience, researchers try to expand their own research lines, interests and knowledge to include multiple analysis perspectives but a real combination of people with different expertise and backgrounds is not fully achieved. I realize this, for instance, when I try to think as a plant physiologist or a geomorphologist or an ecologist to frame some questions. But I’m not, and this affects the way I analyse data and interpret results. I believe a stronger collaboration among different but related disciplines is necessary in order to address scientific aspects of ecohydrology (including the role of anthropic pressure) with a wider angle of view and thus in a less-skewed, more solid way.

I agree with Holly (see her post below) about the scaling issue. Most studies are typically carried out at the plant or stand scale but we still need to figure out how to build models to upscale the spatio-temporal variability in plant water uptake from the plant/stand scale to the catchment/landscape scale. This is an open challenge that has relevant practical implications, for instance for water resource management in forestry and agriculture.

I like the potential (but I’m also aware of the limitations) of meta-analyses (Evaristo and McDonnell, 2017). As far as I, know this approach is quite common in medical science, especially with the aim to increase data availability and reach higher statistical power. I think this tool can have fruitful applicability in ecohydrology in order to achieve a better understanding of processes in a wide variety of environments. At the same time, I advocate the more frequent use of multi-comparison investigations (in ecohydrology as well as in catchment hydrology). Although comparative studies can be time- and money-consuming, through the analysis of differences they can go beyond understanding the behavior of individuals or single study sites and allow for a better perception of the factors that control those differences. And the factors that drive changes in the ecosystems and of their services are what we should be more interested in.
 
Do you have a favorite ecohydrology paper? Describe/explain.
It’s hard to pick just one. Considering papers that focus on the intertwined processes between water and trees, I especially like the review by Susan Brantley and co-authors (Brantley et al., 2017) who tested several hypotheses to highlight how trees, seen as biotic engines, promote soil-landscape co-evolution by acting as “builders and plumbers” of the critical zone. One of the first papers I read when I dove in on the use of isotopes to investigate sources for tree water uptake and related ecohydrological dynamics is the work by Greg Goldsmith and colleagues on ecohydrological processes in a mountain cloud forest in the tropics (Goldsmith et al., 2012). This paper, along with the already-cited and inspiring one by Dawson and Ehleringer, 1991 (I agree with Holly again!) opened my eyes on the exciting opportunities isotopes offer to explore interrelations between vegetation and hydrological processes, including still unsolved (and therefore fascinating) issues. Finally, I recommend a recent paper by Barbeta and Peñuelas, 2017: their isotope-based work underlines the importance of groundwater contribution to plant transpiration across different biomes and provides new insight about the occurrence and interpretation of the highly-discussed “two water worlds hypothesis” (McDonnell, 2014).
 
What do you do for fun (apart from ecohydrology)?
Apart from ecohydrology I do catchment hydrology, of course! Joking aside, I’m a commuter and I’m away very often. So, when at home, I try to spend as much time as possible with my wife and our two children and with our friends, preferably in the outdoors. I love cycling, hiking in the mountains, skiing, playing guitar, reading, and I’m fond of nature photography.

Dr. Enrico A. Yépez is Profesor Investigador Titular “C” at Departamento de Ciencias del Agua y Medio Ambiente at Instituto Tecnológico de Sonora in Ciudad Obregón, México. 

What does ecohydrology mean to you?
This interdisciplinary science has been in the core of my research goals simply because I investigate ecosystem processes in water limited ecosystems. An early realization in my career was that for life, and any biogeochemical cycle, to occur in these systems, water is needed. So, the aim of finding the “functional fate of rainfall” has been central in my thinking and has given me the basis to link hydrological processes with ecosystem production. Ecohydrology also provides knowledge to manage water resources and preserve ecosystems, which are themes that are very relevant in Northwestern Mexico where water is certainly scarce.

What are your undergraduate and graduate degrees in?
I obtained a degree in Biology from the Universidad de Guadalajara in Mexico where I was trained in plant physiological ecology (cacti research). Then I moved to Tucson to get my MS and PhD in Rangeland Management with a minor in Global Change at the University of Arizona (2006). Here is where  I succumbed to study seasonally dry ecosystems.

How did you arrive at working in/thinking about ecohydrology?
In my graduate work I was confronted with a very fundamental issue in ecohydrology: How can we partition the evapotranspiration flux into its components without losing coherence to study processes at the ecosystem scale? This simple, yet fundamental, question obligated me to think about soil, plant and atmospheric processed combined and exposed me to modern technology (flux towers, IRGAs, elemental analyzers and mass spects) to trace the water molecule in ecosystems. Thinking about ET in separated terms demands inquiring how is the biology influencing this physical driven flux and what are the consequences for ecosystem production if water moves through the physical or the biological path.

What do you see as an important emerging area of ecohydrology?
There is still room for finding fine connections between the water cycle and other ecosystem processes. For instance, modelling highly dynamic water and carbon fluxes in pulse driven and seasonally dry ecosystems is still very challenging and it is an area that requires profound ecohydrological criteria. I must mention as well that as water scarcity and pollution augments in the planet ecohydrological knowledge should now confront water management issues.

Do you have a favorite ecohydrology paper?  Describe/explain.
An ecological paper that transmitted an important hydrological message early in my career was the Laureroth and Sala 1992 (DOI: 10.2307/1941874), where the relationship between rainfall and ecosystem production was highlighted but specially how the space by time substitutions are useful to study and integrate ecohydrological processes, an idea that was later on explored by Huxman et al 2004 (DOI:10.1038/nature02561) with a more explicit argument on how this relationship and the space by time substitution is indeed useful to make synthesis and compare ecosystem processes across ecosystems. As nicely depicted by Biederman et al 2016 (doi: 10.1111/gcb.13222) this is an idea that is worth exploiting as we study ecosystem processes nowadays.

What do you do for fun (apart from ecohydrology)?
I enjoy dealing with the analytical instrumentation in lab; I love to see the machines beeping and LEDs blinking while data comes out; I particularly enjoy opening their guts to see how they work. I still try to go out to the field with my students, but when I go home to be with my wife and our two kids (Tlaloc and Ehecatl a.k.a. the Monsoons), card games after a fine Sonoran steak and red wine are usually in order.

Dr. Holly Barnard is an Associate Professor in the Institute of Arctic and Alpine Research and Department of Geography at the University of Colorado – Boulder.

What does ecohydrology mean to you?
To me ecohydrology means “interdisciplinary” research in the most synergistic meaning of the word – where investigating a problem or a curiosity with approaches from multiple fields results in findings that advance our understanding of the greater system. Not every study I pursue matches this ideology, sometimes the advancement is more in one field than the other, but it is a goal to strive for.

What are your undergraduate and graduate degrees in?
Forestry, forestry, forestry! I have B.S. in Forest Resources from the University of Washington, an M.S. in Forest Science from Colorado State University, and dual degree Ph.D. in Forest Engineering and Forest Science from Oregon State University. Um, yeah, I like trees (and water) and at one time I was pretty good at axe throwing.
 
How did you arrive at working in/thinking about ecohydrology?
As an undergrad, I worked in Tom Hinckley’s water relations tree physiology lab and then pursued that research area for my master’s.  After my master’s, I worked in environmental consulting where I did a lot of groundwater and surface water sampling. When I decided to go back to school for my Ph.D. and was presented with ecohydrology as a research option, it was a natural fit and extension of my past experience.

What do you see as an important emerging area of ecohydrology?
I feel that scaling in ecohydrology is a persistent conundrum: when, where, and why (or not) are the ecohydro interactions we observe at the plant, plot or hillslope scale important for processes at the catchment, landscape or global scales? Issues of scale in spatial-temporal data are compounded due to the highly multi-scale nature of ecologic and hydrologic processes. One can argue that all smaller scale processes are important (the small catchment scale and below is where my personal interests lie), but what needs to be included in larger scale, bi-directional models to avoid misrepresentation of either the ecology or the hydrology? Maybe this isn’t an emerging area, but it is certainly a grand challenge.

Do you have a favorite ecohydrology paper?  Describe/explain.
Dawson and Ehleringer 1991: Streamside trees that don’t use stream water
It has is all: streams, trees, mystery, intrigue, and isotopes - all in an elegantly simple study that offers surprises and drives complex questions about the interactions among vegetation, soil moisture, groundwater and surface water. Ecohydrology well before its time. I love this paper.

Newman et al. 2006: Ecohydrology of water‐limited environments: A scientific vision
Early in my Ph.D. I felt like ecohydrology wasn’t a true discipline, but simply that the two fields weren’t reading each other’s literature. This paper provided such a clear articulation of ecohydrology as its own discipline and the grand challenges put forward really helped to guide my thinking in how ecohydrology can be greater than sum of its parts.

In terms of social-media publications, I’m a fan of The Egohydrologist on Twitter.  Their tweets have higher impact factors any of your papers (or so they say).

What do you do for fun (apart from ecohydrology)?
I’m a Boulder stereo-type for outdoor recreation.  I enjoy climbing, road biking, skiing and deadlifting.  I’m also very happy laying on the couch with several pets and watching football. My partner and I enjoy going to the plays at the Denver Center for the Performing Arts.