What does ecohydrology mean to you?
To me, being an ecohydrologist means being a naturalist at heart. You wonder about how things work when you’re out and about, hiking in the woods, climbing a mountain, paddling a canoe. Ecohydrology has also been an academic refuge for me, where I can use the skills that I picked up from engineering to study the wonders of nature. “Water and ecosystems” seems as big a label as you would want, if you wandered into this field through odd paths. Later, ecohydrology also became a kind of camouflage. You can insinuate yourself into the company of people from all areas of expertise, because so many things in the world intersect with water. 

What are your undergraduate and graduate degrees in? 
I have a B.S. in Mechanical Engineering and a minor in Biology from Stanford University, and a Ph.D. in Civil and Environmental Engineering from Duke University. 

How did you arrive at working in/thinking about ecohydrology?
As an undergrad, I spent a lot of time building robots and designing things like battery charging mats for electric cars. At the same time, I also spent quite a bit of time outdoors, backpacking in the Sierra Nevada, or roaming around tropical forests in Australia on a study abroad program. These paths didn’t seem like they could converge until I found “ecohydrology” in grad school – where I could apply the first principles in thermodynamics and fluid mechanics to studying not cars or HVAC systems, but ecosystems. 

What do you see as an important emerging area of ecohydrology?
Since moving to Minnesota, I’ve expanded my ecohydrology lens in two ways: to appreciate the importance of cold climate hydrology (something that I never had to think much about in seasonally dry ecosystems, which was the topic of my Ph.D. and postdoc), and to study ecohydrology in urban settings (which intersects with people’s lived experiences). I’ll elaborate on the first. 
Snow is a huge part of life and water resources here. It also happens that a lot of these colder, perennially inundated watersheds (that contain peatlands) are transitioning from being a carbon sink to a potential carbon source, so snow hydrology both impacts and is impacted by climate change. Snow and frost complicate the timing of when water is available for plant water uptake. They also mediate how the water table regulates greenhouse gas emissions from these watersheds. It’s a complicated and timely problem. 

Do you have a favorite ecohydrology paper?  Describe/explain.
My wonderful Ph.D. adviser, Amilcare Porporato, sent me a paper by Gaby Katul, himself, and Ram Oren titled “Stochastic Dynamics of Plant-Water Interactions” (2007, Annual Reviews of Ecology, Evolution, and Systematics, vol. 38, 767-791) as an introduction to ecohydrology and his particular mode of inquiry. This was me straight out of college, so I didn’t appreciate the depth of the paper at the time, but I’ve since returned to it time and time again throughout my Ph.D. and even now. 
This paper highlights the different timescales over which plant-environmental interactions can manifest, and the fallacy of averages when it comes to extrapolating plant responses across temporal and spatial scales. These ideas were, and still are, important, when long-term monitoring data are becoming increasingly popular and available, for thinking about how we use these data and what they mean. Even now, when I think about “plant water use strategies” or “optimal” stomatal conductance, I revisit these ideas – to place plant responses in the environmental contexts in which they occur. 
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What do you do for fun (apart from ecohydrology)?
To decompress from work, I read, cook, and watch a bunch of TV shows – these also help me stay connected to my extended family in China and Japan. The things that really fire me up are when I get to spend time outside. Since grad school, as a bargain with myself, I make it a goal every year to get unplugged in the wilderness somewhere for a week. The picture above is from when I hydro-geeked out over the Continental Divide in 2019. 

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​Jesse Hahm, Department of Geography, Simon Fraser University

What does ecohydrology mean to you?
Trying to understand the coupled water and carbon cycles through hydrology-tinted glasses by asking how plants both mediate and respond to hydrologic processes.
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What are your undergraduate and graduate degrees in?
I got a BA in philosophy from McGill University, MSc in Geology from the University of Wyoming, and PhD in Earth and Planetary Science from the University of California, Berkeley.

How did you arrive at working in/thinking about ecohydrology?
I was very fortunate to be able to pursue my graduate studies with one foot in a geoscience department and the other in an integrated biology department. I also benefitted immensely from being able to work at two different Critical Zone Observatories (the Southern Sierra and the Eel), where field work was being pursued by teams of hydrologists and plant ecophysiologists working together to try to understand the critical zone. I specifically got hooked on ecohydrology when my PhD advisor confronted me with a landscape-scale puzzle: why, in an area of similar climate, did two very different plant communities exist side by side? There was a clue that geology seemed to be important, but it took a lot of digging to understand how rock type was controlling plant water availability in soil and bedrock.

What do you see as an important emerging area of ecohydrology?
Although we’ve known for decades that plants can use water from bedrock, it’s now becoming clear that this phenomenon is widespread and essential for understanding plant community distribution and sensitivity to drought. A big outstanding knowledge gap is our ability to predict how bedrock water storage capacity varies across landscapes, and why. I’m excited to see the next generation of ecohydrologists combining field datasets with remote sensing and working with geomorphologists and geochemists to advance theories to explain how the subsurface critical zone evolves over million-year timescales.

Do you have a favorite ecohydrology paper?  Describe/explain.
I find myself returning time and again to Scholander and colleagues’ 1965 paper in Science that introduced the now widely used pressure chamber technique for measuring plant water potential (‘Sap Pressure in Vascular Plants’). The ability to measure the tension of the water column inside plants—and relate it to their environment—continues to amaze me. Furthermore, Scholander wrote in an engaging, almost casual style that Is nevertheless precise and credible…I wish I could write like that
 
What do you do for fun (apart from ecohydrology)?
Hiking and mountain biking with family and friends (human and canine), gardening, and house renovations.

What does ecohydrology mean to you?
To me, ecohydrology means: placing water into Douglas Adams’ “Total Perspective Vortex” (TPV) and sharing the experience. No doubt this requires some explanation ;) The TPV is a fictional invention described by Adams in his “Hitchhiker’s Guide to the Galaxy.” The machine could extrapolate “the whole of reality” from whatever was placed before its lens. Although the scientist in Adams’ book, Trin Tragula, used a crumb of cupcake for his extrapolation, an ecohydrologist would do well to place water before its lens, then stare and share the resulting insights. After all, what doesn’t water contain or sustain in ecosystems? 

What are your undergraduate and graduate degrees in? 
I began with a bachelors in Environmental Science and English. Then, I pursued a masters in Environmental Science and Policy and another in Geography. Finally, I earned a philosophical doctorate in Environmental Geography, focusing on how plant canopies intercept, re-distribute, and compositionally alter precipitation.

How did you arrive at working in/thinking about ecohydrology?
I began in hydrology. Eventually, I felt that the field of hydrology had very little wonder about nature. Instead, it seemed to have a lot of interest in controlling nature - controlling water, at least. Water engineering is important, but ameliorating or preventing water issues requires both engineering solutions and reconnecting our modern communities to a personal interest in water. Believing that the latter comes from sowing seeds of wonder harvested from basic research, I left various water engineering questions behind and began discussing water phenomena with ecologists and biogeochemists and such. We’d chat about phenomena that gave me wonder and caused me to care about understanding water… like how droplets of rain holding onto leaves can shine with an amber glow in the setting sun (i.e., chromophoric dissolved organic matter). These discussions led me to start placing drops of water (usually after they’ve hit some part of a plant) into the Total Perspective Vortex!

What do you see as an important emerging area of ecohydrology?
I’m very enthusiastic about a certain topic: how plant canopies intercept and route rain, snow, fog, dew, etc. (precipitation partitioning by vegetation). Despite this topic being of great interest to early natural philosophers, like Thales of Miletus, Theophrastus, and Pliny the Elder, we have paid little attention to it since the dawn of modern science (mostly because these interactions are difficult to measure well). But, canopy-precipitation interactions are often the beginning of various paths that precipitation takes through terrestrial systems. Thus, if we get it wrong there, we may propagate our errors into our understanding/modeling of all proceeding water-related natural phenomena.

Do you have a favorite ecohydrology paper?  Describe/explain.
I really enjoyed working through the old paper “Der Wald und die Quellen” from the poet-forester, Carl Eduard Ney. It’s written in old school German and my quest to digest it required help from my German friends (Jan Friesen and Johanna Metzger) and family (mostly my saint-of-a-wife, Stefanie). Ney shares a unique view of early forest ecohydrological measurements and understanding - during a time where technological and numerical capabilities were limited just enough to inspire clever, simple solutions for gaining valuable field insights. Ney was also the first person, in the written record, to start measuring the water that runs down tree trunks (stemflow) during rain, snow, rhyme, and even dewfall. His poetic wonder about nature really comes through! I hope that we in the forest ecohydrological community will remember his contributions.
Der Wald und die Quellen; Published by F. Pietzcker: Tübingen, Germany, 1893; https://www.google.com/books/edition/Der_Wald_und_die_Quellen/xOe2Ut4H3r0C?hl=en

What do you do for fun (apart from ecohydrology)?
I like to write poetry with my sons, make music with other musicians, and record audiobooks… then post them all to YouTube. There is also ample time for doodle snuggles with my doge, Rosco.

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