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Darby, Yujie, and Andrew are coauthors on a paper led by Jeffrey Uyekawa and Ben Lucas of NAU’s Department of Mathematics and Statistics in a special Landscape Ecology section of the journal Land. The study uses the Extreme Gradient Boosting machine learning model to model land-atmosphere CO₂ fluxes, at 30 minute temporal resolution, across 44 NEON sites. In addition to standard k-fold cross-validation techniques, the study applies a “leave-one-site-out” (L1SO) approach to test predictions at a site which had not been used, in any way, to train the model. The results show strong potential for machine learning-based models to make more skillful predictions than state-of-the-art process-based models, being able to estimate the multi-year mean carbon balance to within an error ±50 gCm⁻²y⁻¹ for 29 of 44 test sites. L1SO model performance was better when ecologically similar sites were included in the training data, and worse when there were no similar sites in the training data (e.g., more unique ecosystems in the Pacific Northwest, Florida, and Puerto Rico). Results also point to the enormous potential of machine learning to predict not only the long-term carbon balance of an unknown site, but even the inter-annual variation in that carbon balance.  These results have significant implications for being able to accurately predict the carbon flux or gap-fill an extended outage at any AmeriFlux site, and for being able to make skillful predictions of ecosystem-scale carbon balance in support of natural climate solutions.

A companion paper on water fluxes is in preparation.

NEON tower at Niwot Ridge, Colorado (courtesy of NEON).

Mark D. Schwartz, University of Wisconsin–Milwaukee, is well-known for his pioneering efforts—beginning in the 1980s—to bring the science of phenology into the modern era. He is also highly regarded as the editor of the book Phenology: An Integrative Environmental Science. The third edition of this book, published by Springer, was recently released. Across 644 pages, the book’s 27 chapters span a wide range of topics. You’ll see lab members’ names on several of those chapters:

• Perry and Andrew wrote the chapter on Mesic Temperate Deciduous Forest Phenology. Special congratulations to Perry on his first first-author publication!

• Oscar and Andrew wrote an updated version of the chapter on Near-Surface Sensor-Derived Phenology.

• Darby and Andrew contributed to the chapter on Phenology in Higher Education, which was led by long-time collaborator Theresa Crimmins of the USA-National Phenology Network.

The Autumn-Winter 2024 edition of Redwoods Magazine, published by Save the Redwoods League (SRL), includes an article by writer Kathleen Ok-Soo Richards on “the hidden, interwoven relationship between fog and coast redwoods.” The article focuses on new research funded by SRL to “better understand how coast redwoods might adapt to shifting fog patterns in the future and how we can support them.” One of three projects highlighted is the work Andrew and George Koch are doing to investigate whether seasonal and daily tree growth is related to nighttime fog availability. With a new grant awarded in December 2024, ongoing work at the southern edge of range of coast redwood will be complemented by a new study at the Sequoia Park Zoo in Eureka, California, where fog is a far more regular occurrence. In addition to installing instruments to measure tree growth and water stress, Andrew will be moving his Vaisala ceilometer to the new research site to provide detailed information on fog conditions.

Thanks to SRL for supporting this work!

Photo by Max Forster, https://www.savetheredwoods.org/

This semester, we had two visiting students in the lab, Francisco and Teresa.

After the AGU meeting, Francisco returned to his native Ecuador for the holidays. He will resume his studies at Newcastle University in the new year.

Teresa’s parents, Clara and Pablo, made the long trip up from Hermosillo, Mexico, to visit Flagstaff in mid-December at the end of Teresa’s visit. Teresa will resume her studies at the Universdad de Sonora (UniSon) in the new year. The photo below Teresa with her parents (very happy and proud that she is “fulfilling her dreams of becoming a scientist”) at the entrance to the Ecoss suite. Teresa returns to Mexico with a StarDot NetCam SC in hand and plans to push for greater Mexican involvement in the PhenoCam network. This is a collaborative opportunity Andrew has been looking forward to for years; in the paper describing Version 2 of the PhenoCam dataset, it was noted that “most of Mexico emerge[s] as poorly-represented in this analysis. These […] areas […] should be targeted for further expansion of the network.” We hope Teresa’s visit can help make this dream a reality!

Thank you Francisco and Teresa for your visits and your contributions to the lab this semester. We all look forward to future collaborations, and the long-term friendships that result from these kinds of visits. Best wishes for 2024!

Another December, another AGU! The lab was well-represented in Washington, D.C., for the “What’s Next for Science?” theme year, with in-person attendance by Mostafa, Jen, Yujie, and Francisco (top photo). Highlights included: 

• Two sessions (bottom right photo) organized by Mostafa, “Advancing Environmental Monitoring Through Near-Surface Imaging Technologies: Capabilities, Applications, and Future Directions” and “Understanding Phenological Responses, Changes, and Feedbacks: Patterns, Mechanisms, and Consequences.”
• Two talks by Jen (AGU first-timer!), “The Great Thermal Bake–Off: A Hands-On Workshop for Enhancing TemperatureMeasurement Precision and Standardization for Improved Flux Interpretation and Application” and “Deciphering the Controls on the Canopy-to-Air Temperature Gradient Across Diverse Plant Functional Types.” 
• Yujie had a talk, “Evaluating continuity of NEON and AmeriFlux data records at collocated sites from tundra to subtropics” (bottom left photo shows Yujie and Dave Moore, University of Arizona).  
• Francisco had a talk, “Optimising Traffic Camera Networks for Long-Term Phenological Monitoring Via Advanced Image Clustering Techniques.”
• Mostafa also had a poster, “Tracking vegetation phenology across diverse biomes using Version 3.0 of the PhenoCam Dataset.” 

Next year’s AGU meeting is in New Orleans, Louisiana — see you there!

Sam Illingworth is a science communication scholar from the UK. Sam’s particular area of interest is poetry as a communication tool, and every week he picks a new paper, writes a nontechnical summary, and crafts a poem – which he then records and posts online.  Sam shared his unique approach to science communication this semester in an engaging and highly creative virtual presentation for the Ecoinformatics Seminar. Follow-on communication between Andrew and Sam led to Sam using the recent PNAS paper by former lab visitor Raquel Alfaro-Sánchez  as inspiration for this week’s poetry creation and blog post.

Sam’s evocative reading of his poem, Drunken Forests, is available on SoundCloud through the link below.

Thanks, Sam, for helping us to share this work with a wider audience!

Arizona Research Computing, in partnership with Arizona’s major universities and the Sun Corridor Network, leverages supercomputing and data stewardship to drive innovation across the state. Earlier this fall, Andrew was interviewed for a video, “Arizona Research Computing: Enhancing research with computing and data stewardship,” showcasing how advanced computing resources enable groundbreaking research with direct benefits for Arizona’s environment, economy, and communities, emphasizing its substantial impact on Arizona. The video, featuring some great footage of work in the redwoods and also PhenoCam time lapses, was shown at the recent SC24 conference in Atlanta, Georgia, where the meeting theme was “HPC Creates.”

We had another fantastic lineup of speakers in Andrew’s class INF 623, Ecoinformatics Seminar. Mostafa provided invaluable TA support and technical assistance – thank you!

Thanks to all the speakers for their fantastic and diverse presentations.

Seminar resumes in January with another great lineup for Spring 2025.

Way back in 2022, Raquel Alfaro-Sánchez (a postdoc at Wilfrid Laurier University in Waterloo, Canada) visited the lab to learn about nonstructural carbohydrate (NSC) analyses. During her visit, she analyzed samples from black spruce trees collected from 15 sites in low subarctic and high-mid boreal forests in the Northwest Territories, Canada. The sites varied in the depth and stability of permafrost. Results from Raquel’s work have been published in the paper, “Permafrost instability negates the positive impact of warming temperatures on boreal radial growth“, out this week in PNAS.

Also this week, former postdoc Drew Peltier’s paper, “Decades-old carbon reserves are widespread among tree species, constrained only by sapwood longevity“, has been published in New Phytologist. Drew’s paper synthesizes data on the radiocarbon (¹⁴C) content of NSCs in nine different tree species, including evergreen conifers, and both ring- and diffuse-porous angiosperms. The ¹⁴C data enable estimation of the age of NSC reserves, and were used with a new model describing the distribution of NSC reserves across rings to investigate how the distribution, mixing, and turnover of reserves vary across trees and species. Drew’s paper shows that deep mixing and rapid turnover indicate most photosynthate is rapidly metabolized. Across species, maximum reserve ages appear primarily constrained by sapwood longevity, and thus old reserves are probably widespread.

Coast redwood (Sequoia sempervirens; SESE) was one of the nine species included in Drew’s recent paper. This photo shows Alatna Richardson at the base of a spectacular SESE known as Triclops, in Prairie Creek Redwoods State Park, California.

Oscar, Teresa, Perry, and Darby visited Grand Canyon Elementary School as part of the Flagstaff Festival of Science In-School Speaker Program. They worked with 3rd through 5th graders to explore phenology, ecosystems, and how PhenoCams are used to monitor seasonal changes in plants. Each classroom received a brief introduction to these topics, followed by a variety of hands-on activities. Students arranged PhenoCam images of ecosystems by season, identified ecosystem disturbances like droughts and wildfires through photos, and matched images to the correct ecosystem type. There were also fall-themed arts and crafts projects to connect science with creativity. The fifth graders had the opportunity to explore the PhenoCam website, using the map to investigate seasonality at different locations. Fourth graders were deeply engaged, asking thoughtful questions and contributing insightful answers during the activities. In the third-grade classroom, Teresa, a visiting graduate student, provided a multilingual element by teaching students how to say the four seasons in Spanish. Overall_, it was a successful outreach event — thanks to the elementary school teachers for the invitation!