For the past 3 years or so, I have been an online scientist mentor for the Planting Science program. This is a great way to reach out to students at the middle and high school levels on a weekly (and more often usually) basis and discuss plant biology, experimental design, data analysis, and presenting ideas - especially when somewhat cloistered away from students at a non-teaching institute. The Planting Science program connects scientists with high school and middle school teachers and classrooms, and assigns scientists to groups of 2-4 students during a ~6 week module on a topic in plant biology. Students brainstorm and design experiments with feedback from the scientist mentor and their teacher, and we connect through email messaging and the occasional class skype session. For the past few years I've mentored 2 teams each semester, and had a blast guiding them through their experiment via open questions and answering their queries on "scientist life" as well as basic concepts.
I am proud to announce that I applied and was selected to be a "Digging Deeper" Fellow with PlantingScience. This fellowships includes traveling to a workshop to collaborate with high school and middle school teachers in Colorado Springs this summer, and work on improving a few of the modules for classrooms, and then being the lead scientist mentor for two classrooms in the fall. My experiences with Planting Science have been great so far, and I think it's an excellent way for teenagers to learn not only about plants, but also that scientists are real (mostly) normal people, and doing science is a job that is not as removed from their lives as they might think based on media depictions. Very excited to head to CO this summer and continue working with this great organization!
Much to report on my end in the last few months - it has been a productive (and reproductive) few weeks/months on my end. Foremost, Will and I welcomed our daughter into the world in mid-February! She is robust and healthy and wonderful - though quite a lot of work to keep her fed! I'm off on maternity leave for the next couple of months to enjoy, practice and learn to be a mother.
In other news, this has been a productive winter for publications. I have been part of many projects and writing teams - ranging from my old research stomping grounds in Arctic Alaska (Prager et al), to the excellent New Phytologist meeting on the Kok Effect that took place in Angers, France last July (Tcherkez et al.), to local phenology projects at Harvard Forest (Yang et al.), to stoichometry in a tropical forest (Mo et al.), to the application of revised acclimation and temperature response equations in global vegetation models (Huntingford et al). The wide range of these projects, and being a part of them in different capacities (data collection, writing, analysis, meeting participation, etc), really makes me happy to be where I am today - part of many diverse groups pushing for new approaches and understanding of how plants are impacted by the environment, and how to capture this variability quantitatively.
Okay - I hear someone is hungry... Full citations of accepted publications below. Others listed above are in revision - hopefully accepted soon!
Prager C, Naeem S, Boelman N, Eital J, Greaves H, Heskel MA, Magney T, Menge D, Vierling L, Griffin KL. (2017) A gradient of nutrient enrichment reveals non-linear impacts of fertilization on Arctic plant diversity and ecosystem function. Ecology & Evolution. Accepted.
Tcherkez G, Gauthier P, Buckley T, Busch F, Barbour MM, Bruhn D, Heskel MA, Gong XY, Crous
KY, Griffin KL, Way DA, Turnbull MH, Adams M, Atkin OK, Bender M, Farquhar GD, Cornic G.
(2017) Tracking the origins of the Kok effect, 70 years after its discovery. New Phytologist. Accepted.
Yang H, Yang X, Zhang Y, Heskel MA, Lu X, Munger W, Sun S, Tang J. Chlorophyll fluorescence
tracks seasonal variations of photosynthesis from leaf to canopy in a temperate forest. (2017) Global
Change Biology. Accepted. doi: 10.1111/gcb.13590
Temperature response of soil respiration largely unaltered by experimental warming - Carey et al. now out in PNAS
I'm proud to announce that Joanna Carey (my lab mate, house-mate in Woods Hole, good friend, and now co-author, had her massive meta-synthesis published in PNAS this week. This work is a large effort with over 20+ co-authors who all contributed either analytical and writing input and/or raw data from multiple field sites.
Collectively the data show that experimental warming experiments, regardless of the duration of the experiment or the type of experiment (infrared heating, passive warming, buried cables, etc), does not significantly alter the temperature response of soil respiration in many ecosystem types. This implies that under future, warmer climates, soil respiration will likely show a similar response to current ambient temperatures - neither acclimated or enhanced. While respiration still generally increases with temperature, the degree of increase is unchanged under experimental warming. This is a great contribution to the literature, and a huge team effort led by Joanna.
The paper can be found here:
After publishing on the new Global Polynomial Model of the short-term temperature response of respiration, based on 231 species' response curves measured at high resolution, we (the author team) received responses through email and more recently through a letter to PNAS on alternatives to our findings and conclusions. The response by Adams et al (http://www.pnas.org/content/early/2016/10/03/1608562113?trendmd-shared=0) used our open data on the model fit parameters and applied these to an alternative R-T response model based on an Arrhenius fit. The authors found similar convergence in the response across Biomes and PFTS - confirming our major finding that the response of respiration to temperature is conserved across diverse species and climates. The authors suggest an alternative, more 'mechanistic' approach to modeling this response in addition, or as an alternative to the model we presented.
We responded to this response (http://www.pnas.org/content/early/2016/10/03/1612904113?trendmd-shared=0) with an acknowledgement of their modeling approach, though a disagreement in what we view as mechanistic/process vs. phenomenological model. For instance, the use of a 'activation energy' does not necessarily make a model a process model (say, compared to the Farquhar equation), as there are so many overlapping processes involved in respiration, that this activation energy actually describes a suite of reactions. I was encouraged by the convergent finding, and the gracious and supportive discourse about models and how they are applied at different scales. This interaction was not competitive, ego-driven, or angry, as can be the case in science, but rather driven by ideas, competing hypotheses (not labs!) and used data to back up arguments. I appreciated the challenge, and the opportunity to reframe ideas to emphasize our main points in the first paper. Kudos to Adams et al for bringing alternatives to the party, and opening this discussion.
Joanna Carey, a fellow postdoc at Ecosystems Center at MBL and Woods Hole housemate, had her excellent manuscript on soil warming accepted by PNAS last Friday. This manuscript is novel in that it amassed a huge amount of real measurements of soil respiration taken in ambient and warmed experimental plots from sites around the world, and analyzed the fluxes and soil temperatures to determine that the temperature sensitivity of soil respiration was common in control and warmed plots. Thus, despite long term warming, the rate of response of soil R is conserved in control and warmed soils - simplifying modeling long-term warming effects.
This study was funded by a USGS Powell Center Working Group led by Jim Tang (MBL), Pam Templer (Boston University), and Kevin Kroeger (USGS). I participated in the first of the working group meetings, but had to miss the second due to field work schedules - it was a great experience, and I'm so pleased that this analysis is now accepted at PNAS. Congrats, Joanna!
Details on DOI, etc to come after it is formatted and published.
Our new Global Change Biology paper is garnering media attention in Australia, where many of the species we measured for high temperature physiology occur. This study, led by Odhran O'Sullivan, covers the response of fluorescence and respiration at high temperatures in more than 200 plant species across a wide range of ecosystems and climates, and data for this study was collected at over a dozen field sites. Analysis revealed the plants existing in more temperate regions may be at an even greater risk than tropical systems based on physiological measurements and predicted future climate. Some of the articles are linked below:
Sydney Morning Herald:
Owen Atkin interviewed by the ABC:
http://www.abc.net.au/news/2016-09-14/study-warns-of-tipping-point-for-inland-plants/7843326This week, I've been guiding the canopy photosynthesis lab for the Semester of Environmental Science at The Ecosystems Center
This week also marked my second year of leading the photosynthesis lab for the Semester of Environmental Sciences at The Ecosystems Center at the Marine Biological Laboratory. For this week long lab, we went to the field on Monday and measured gas exchange using my old friends the 6400s and fluorescence using a brand new WALZ PAM Jr. The fluorescence aspect of the lab is brand new, and after some background in lecture from Zoe Cardon, I think the students were able to grasp the proportional variation of NPQ, ETR, and quantum yield by measuring a rapid light response curve. On Tuesday, Wednesday, and Thursday, the students will work up their data from the IRGA and PAM measurements, and develop a modeled canopy, where photosynthesis is driven by PAR through the day at two canopy heights. Many of the students are still beginners when organizing and applying data, so this lab helps build concepts of modeling, using error minimization to optimize your model, and applying data they collected to a idealized system. Next week, groups will present their findings. Always a good day when you get to teach about photosynthesis.
Good news from the weekend: a paper I am co-authoring with Odhran O'Sullivan, Owen Atkin, and others recently got accepted to Global Change Biology.
The paper covers a large dataset of high temperature thresholds of respiration and chlorophyll fluorescence in species measured in arctic to tropical ecosystems. More later when it is out in pre-print edition!
So much time has passed since I last posted - guilt (and procrastination) have finally kicked in to a motivating degree!
Also, so much has happened since late March...a brief bulleted recap list below. I will attempt to go into more detail about each item in the next month.
More detailed updates soon!
Chris Neill and Kelly Holzworth graciously put together a blog post for the study that is now posted on the Ecosystems Center homepage. The Arctic LTER site that is managed by scientists at Ecosystems Center was the only arctic tundra site used in the study, included ~20 species of C3 herbs, evergreen shrubs, and deciduous shrubs, which fleshed out many PFT categories for the study. The Arctic plants had the highest rates of respiration per area when measured at the same temperature, which is to be expected.
More here: http://www.mbl.edu/ecosystems/global-study-of-tundra-to-desert-plants-shows-leaves-respond-to-warming-in-remarkably-similar-ways/