This is the next in a line of periodic interviews with Fluxnet Young Scientists. This month, we’re glad to introduce Eugénie Paul-Limoges, who is a third-year PhD student supported by a Canadian Natural Sciences and Engineering Research Council (NSERC) scholarship at ETH Zurich, Switzerland. Eugénie received the AMS Student Presentation Award for her MSc work in 2014 and was the winner of an Outstanding Student Paper Award at AGU for her PhD work in 2015 (link). Since 2015, she is also part of the AMS board on Atmospheric Biogeosciences. More information on Eugénie is available through her ResearchGate Link.
Please tell us about yourself.
I had the privilege to gain research experiences early on during my B.Sc. at the University of British Columbia. I first worked as a research assistant for the Tree Ring Lab under the supervision of Lori Daniels. Lori was an inspiring teacher, who could not hide her passion for trees while teaching us in the west coast forests of British Columbia. Through my B.Sc. project with her, I learned a lot about forest ecology and regeneration dynamics, and I developed a strong enthusiasm for pursuing hands-on research outside in nature. I also worked for two years as a research assistant in the Micrometeorology Lab under the supervision of Andreas Christen on a project investigating the influence of mountain pine beetles on CO2 fluxes. Andreas always provided me with opportunities to learn new skills such as programming dataloggers or calibrating sensors, while allowing me to work on interesting research questions. Throughout my B.Sc., I became deeply passionate about micrometeorology, ecology and soil science, and I was trying to find a way to combine all these passions together into one field. Once I discovered biometeorology, it was without a doubt the field in which I wanted to pursue my career. I had the incredible privilege to do my M.Sc. under Andy Black’s supervision, and to learn biometeorology from its theoretical beginnings until now. Meeting with Andy sometimes felt like having a direct access to a biometeorology encyclopedia, and his vast knowledge of the field allowed me to get a strong foundation. I learned about eddy-covariance measurements from the theory to the installation in the field, to the maintenance and calibration, to ensuring proper QAQC, and to having final fluxes gap-filled and partitioned. My M.Sc. project focused on the effect of harvesting on the CO2 fluxes of a Douglas-fir forest (see Eugenie Paul-Limoges et al. 2015 AgForMet). I studied a unique forest site on Vancouver Island where eddy-covariance fluxes had been measured for 11 years pre-harvest, and I investigated the change in CO2 fluxes for three years post-harvest.
Despite my deep attachment for Vancouver and UBC, I was well aware that I had to be mobile to have a chance at pursuing a scientific career in biometeorology, and I was also looking forward to new challenges to broaden my skills and expertise. I found the ideal project for my PhD in the Grassland Sciences Group at ETH Zurich, which combines eddy-covariance fluxes with ecophysiological and remote sensing measurements. My project is part of the Swiss Earth Observatory Network (SEON) and it has been a great learning opportunity through collaborations with colleagues from the Remote Sensing Laboratories at the University of Zurich (see for e.g. Damm et al. 2015 RSE).
Please tell us about your recent studies. What’s the main take-home message?
One part of my PhD project, which I presented at AGU and more recently at the AMS conference, is to partition the contributions of the understory and overstory to ecosystem CO2 fluxes in a temperate mixed forest. Since airborne remote sensing measures only the top of the canopy while fluxes integrate over the entire ecosystem, the goal of this study was to partition the fluxes coming from the overstory canopy and compare with top of canopy remote sensing measurements. However, as is often the case in science, the story of the below and above canopy fluxes was more complex than expected and required further investigation. In this study, we found a decoupling of the below and above canopy fluxes under full canopy closure. This decoupling resulted in an overestimation of the net ecosystem production measured above the canopy due to the underestimation of respiration, as the fluxes below the canopy are dominated by soil respiration. We were able to correct the above canopy fluxes using the below canopy measurements, and following the correction the above canopy fluxes agreed well with net ecosystem production determined independently using biomass inventories combined with models. This study really showed the benefit that adding below canopy eddy-covariance measurements can have at some forested sites. At our forest site, such below canopy measurements are essential to gain reliable estimates of the CO2 exchange.
As you work more with flux data, what skills do you feel you need to acquire (either in the past or near future) to make your studies more effective?
I have now been working with flux data for about 5 years through my M.Sc. and PhD. I do most of my work in Matlab, but I feel more and more the need to learn different programming languages to be more polyvalent. Through my PhD work, I have been learning some python and R, but it takes time to become as fluent in different programming languages, so this is definitely something to invest time on. Also, I feel like we enter an era in biometeorology, where we can no longer just focus on the eddy-covariance fluxes but rather we need to become more interdisciplinary. I am happy that my PhD project allows me to collaborate and learn from experienced colleagues in ecophysiology and remote sensing.
What resources do you think the flux networks or communities have provided or could potentially provide to help your studies or career?
The sites where I work in Switzerland are part of Swiss Fluxnet, which I believe is a very important network in ensuring the long-term continuity of eddy-covariance sites. Same for all other Fluxnet sites located at different locations worldwide. While I was in Canada, the sites where I worked used to be part of Fluxnet-Canada, which no longer existed by then. When such networks no longer exist, it is very difficult to maintain sites over longer time periods and we end up losing precious measurements. During my M.Sc., many sites ceased to exist in Canada because of lack of funding, some of which I had to take down myself which is never a great experience, as you see years of invested work and the potential of such sites if maintained longer. Just before I started my M.Sc., the oldest site on Vancouver Island reached maturation and was harvested, which led to a unique study looking at this same forest site from pre- to post-harvest. As the time series at many Fluxnet sites worldwide grow longer and longer, more sites where measurements are currently on-going will experience disturbances and then such sites provide perfect opportunities to understand the effect of a disturbance at a specific site without the use of chronosequence studies. Therefore, I think such flux networks are extremely important for continuous measurements over years to decades.
Flux communities such as the Fluxnet YSN have also been a great mean of meeting colleagues, sharing experiences and exchanging ideas. Going to conferences is for me very exciting, but can also be intimidating, especially the first time you present in front of 300-400 people. Through the Fluxnet YSN, I got to meet a lot of people going through similar experiences and it makes you feel not alone in this process. I also got to learn about the projects of other young scientists and sometimes collaborations can arise from such discussions. These networks allow us to stay updated about what is being done where and under which conditions, so that we are well informed by the time we are looking for the next position.
What are your career goals and aspirations?
I really, really enjoy doing research in biometeorology so I hope to be able to keep doing this for many more years to come. I will be finishing my PhD in February-March 2017, so I will soon be looking for a new opportunity most likely as a postdoc or otherwise as a scientific researcher. I was inspired to pursue my career in research because I had the privilege to have early on inspiring teachers and mentors that shared with me their passions for science. I would love to be able to do the same one day by having a professorship position or a scientific research position. It is important for me in science to work in a fair and constructive environment, where merits are based on achievements rather than politics and where people are open to different perspectives – I think this is where the best ideas arise!
— Texts, photos & figures are provided by Eugénie Paul-Limoges —
- Damm A, Guanter L, Paul-Limoges E, van der Tol C, Hueni A, Buchmann N, Eugster W, Ammann C, Schaepman ME (2015) Far-red sun-induced chlorophyll fluorescence shows ecosystem-specific relationships to gross primary production: An assessment based on observational and modeling approaches. Remote Sensing of Environment 166: 91-105 doi:10.1016/j.rse.2015.06.004.
- Paul-Limoges E, Black TA, Christen A, Nesic Z, Jassal RS (2015) Effect of clearcut harvesting on the carbon balance of a Douglas-fir forest. Agricultural and Forest Meteorology 203: 30-42 doi:10.1016/j.agrformet.2014.12.010.