Botany 2021

transcript for Winter Twig Phenology An Experiment & Writing Assignment (bud)Bursting with Potential

Slide 1: “Winter Twig Phenology: An Experiment & Writing Assignment (bud)Bursting with Potential” with photos of coauthors Caitlin McDonough MacKenzie & Abby Pearson

CAITLIN: Welcome! Let’s talk about Winter Twig Phenology: An Experiment & Writing Assignment (bud)Bursting with Potential. I’m Caitlin McDonough MacKenzie, I’m a Visiting Assistant Professor in Environmental Studies at Colby College. And my coauthor is Abby Pearson, a Laboratory Instructor in Environmental Studies at Colby.

Slide 2: A photo of Colby College campus in the twilight, very idyllic and woodsy, and the Colby College logo.

CAITLIN: Colby is located in what we now call “Maine” on the homelands of the Wabanaki people, which includes the Abenaki, Maliseet, Micmac, Passamaquoddy, and Penobscot Nations. For thousands of generations, and still today, Wabanaki people have lived here, and aligned hunting, foraging, fishing, and gathering practices with seasonal changes. Our research monitoring phenology is not new: we study leaf out knowing that we are just one of the most recent observers to attend to this sign of spring.

Slide 3: A photo of dormant twigs sitting in a lab window, outside there is a snowy scene. Photo credit: Elle, Jimmy, Chris (students in the class)

CAITLIN: Today we are presenting a winter twig phenology lab we developed together for Spring 2021. As we process the trauma of teaching during the COVID-19 pandemic, we want to dust off one of our silver linings and share our experience. Transitioning existing courses to new modes often forced us to reexamine course materials and exercises. The approaches and assignments that met clear learning goals with simple methods, outdoor fieldwork, and low-stakes but meaningful assessments which we developed under pressure this year can become staples in our future curricula. For example, here, we present a lab experiment and accompanying writing assignment for undergraduates that we developed for an in-person lab component of a semi-remote Forest Ecosystems class.

Slide 4: Bullet point text that reads “Spring 2021

• 300-level Forest Ecosystems

• Nine students: sophomores - seniors, Biology and ES majors

• Remote Lecture, In-person, on Campus Lab

• 472 acres of campus woodlands”

CAITLIN: Spring 2021 was a challenging semester! Here are the bullet points of our experience. In Fall 2020, I started at Colby. Abby and I were a part of a wonderful teaching team that shifted the lectures and labs of Intro to Ecology into a completely remote mode for 90 students. In Spring 2021, Abby and I taught Forest Ecosystems. I was a sabbatical replacement for Justin Becknell. We offered this upper-level ES course with a remote lecture (me) and in person, on campus lab taught by Abby. Nine upperclassmen enrolled for the adventure.

Slide 5: Text: “Forest Ecosystems Learning Goals

• Gain knowledge on:

  • The extent and status of forest around the world, with special attention to Maine

  • Forest composition and structure

  • Forest ecosystem processes and function

  • Forest management and restoration

• Learn the skills to:

  • Be efficient and critical consumers of scientific literature

  • Write a publication quality literature review

  • Collect field data on forest ecosystem properties and processes

  • Share your knowledge on forest structure and function through written and oral communication”

CAITLIN: Overall the course goals of Forest Ecosystems included emphasis on writing and field skills.

Slide 6: A photo of dormant twigs sitting in a lab window, outside there is a snowy scene. Photo credit: Dominick & Grace (students)

CAITLIN: We developed a winter twig phenology lab project to kick off the semester of Forest Ecosystems. This is the story of the lab, the associated writing assignments, and how it came together.

Slide 7: A photo of Richard Primack and his graduate students and undergraduates holding cut twigs circa 2014. Photo credit: Primack Lab

CAITLIN: This lab project was inspired by my experiences as a PhD student in the Primack Lab at Boston University. I had helped my labmates, Caroline Polgar, Amanda Gallinat, and Lucy Zipf with winter twig experiments. We collected twigs from trees and shrubs in the Boston area and brought them indoors for a simple leaf-out phenology experiment under different chilling units. Basically, in a typical year, twigs collected in February experienced fewer chilling units than twigs collected in March.

Slide 8: A photo of cut twigs, some dormant, some leafing out, in Dunkin Donuts iced coffee cups in a lab. Photo credit: Amanda Gallinat

CAITLIN: I had plenty of experience arranging dormant twigs in Dunkin Donuts iced coffee cups with my labmates, but I had never led my own twig experiment. In fact, I spent all my PhD fieldwork observing leaf out and flowering phenology in Maine and documented a pattern of weakened phenological sensitivity in northern plant populations compared to conspecifics in southern New England: from sites at the coast to the interior of Maine, shifts in leaf out and flowering measured from contemporary and historical data matched the direction, but not the magnitude, of changes noted in Massachusetts So, for our class, Abby and I wondered, What if we replicated the twig experiments in Maine?

Slide 9: A cartoon of comparing “Strong Chilling Requirement” and “Weak Chilling Requirement.” Under each label there’s a twig collected in February and a twig collected in March. The February twig has two snowflakes and the March twig has four snowflakes. All snowflakes are followed by a cartoon sunshine.

CAITLIN: This experiment unpacks the roles of winter chilling and spring warming in driving leaf out phenology. If a species has a strong chilling requirement, we expect that the March twigs (with extra snowflakes for chilling units) will leaf out faster than the February twigs. For example, if the February twigs leaf out ten days post collection, the March twigs might need only three days to leaf out indoors. If a species has a weak or nonexistent chilling requirement, we expect that the March and February twigs will have the same time to leaf out (for example, the both leaf out one week post collection)

Slide 10: A long list of “Project Learning Goals” Text:

• Practice winter twig identification

• Get comfortable with field and lab methods

• Practice phenology observation skills

• Compare observations to published results

• Place this experiment in the context of phenology research

• Practice writing a section of a scientific paper

• Read and synthesize peer reviewed papers

• Use Mendeley to manage your references and build in-text citations

• Identify outstanding questions or knowledge gaps in phenology research

• Develop hypotheses, supported by the literature, for the phenology experiment

CAITLIN: We compiled a long list of learning goals for our twig lab. These were presented to the students in a lab hand out (before their fieldwork began) and a writing hand out. In the future, we will probably simplify and streamline these.

Slide 11: Text: “Field and Lab Work”

CAITLIN: We opened the semester with our winter twig project!

Slide 12: A cartoon of a twig with labels for the nodes and notes on how to collect twigs for the experiment. Text: “Twig collection and observation: At least two nodes per twig, 5 twigs per tree, Record observations, Leaf-out on any bud “counts” for X / 5”

CAITLIN: Abby presented a short powerpoint on leaf out phenology (it looked very similar to the slides you are seeing today!) It opened by asking students, Why do deciduous trees drop leaves over the winter? How do trees “know” when to regrow leaves? After introducing the concepts of chilling requirements and heat sums or spring warming, Abby explained the basics of winter twig experiments.

Slide 13: A cartoon of collected twigs.

CAITLIN: Each group would choose two taxa to collect from the Colby campus. On February 18, our first field lab, the groups identified two to three trees of each taxa, and collected 5 twigs from each tree. Over the next few weeks, we measured time to leaf out in days since collection. On March 11, they collected the next round of twigs from the same individual trees We encouraged students to start thinking about two lines of questions: what differences in time to leaf out would they see between the two collections? And what patterns would they see between twig experiments in Massachusetts (led by Caroline Polgar) and in Maine?

Slide 14: A map of New England with the locations of Concord, Mass and Waterville, Maine marked.

CAITLIN: We highlighted the comparison to Massachusetts for a few reasons: First, it was the inspiration for our lab project, and we tried to direct students towards choosing taxa that were in the Massachusetts study. And second, Caroline Polgar is a Colby alumna and she joined us by video chat about halfway through the project to talk about her research and the origins of the twig studies.

Slide 15: A graphic schedule of the Forest Ecosystems Lab with important deadlines noted. Clippings: Feb 18 and Mar 11, Writing Assignments: Reading: Feb 25, Hypotheses: Mar 4, Outline due: Mar 11, Draft due: Mar 18, Final due: Mar 25.

CAITLIN: This was our lab schedule. This project stretched over seven weeks. The field work to collect the twigs took up two full lab periods on the 18th and 11th. In other weeks, students monitored their twigs before or after the lab and on Monday or Tuesday. All writing assignments were due at the beginning of lab period (but across the board I had a policy of “goalpoast” dates rather than hard deadlines with no late penalties for assignments this semester). Before we get into the writing assignments, here are our “results”...

Slide 16: A collage of the cut twigs: American beech, Paper birch (photo credit: Dominick & Grace), Apple (photo credit: Margot & Sophie), White Ash, Red Oak (photo credit: Elle, Jimmy, Chris)

CAITLIN: Students shared photos of their twigs from the week of March 11

Slide 17: A photo of cut twigs. Written in sharpie at the top: “Collected Jan 8-11, 2013. Today is Feb 8, 2013.” There are three columns of twigs: “Native trees” with only paper birch leafed out, “Native shrubs” with high bush blueberry and stag horn sumac leafed out, and “non-native invasives” with buckthorn, euonymus, bittersweet, and Japanese barberry leafed out.

CAITLIN: When I was a student in the Primack lab, we made this visual of our twig results. Lab members have been using this photograph in presentations for years, and it was published in a review of twig phenology methods in 2015. There’s a clear pattern of reduced chilling requirements in non-native invasive species compared to native trees.

Slide 18: A similar photo of cut twigs. Written at the top: “Collected Feb 18, 2021, Final Observation Mar 18, 2021” There are tiny leaves on Betula papyrifera, Acer saccharum, Quercus rubra, Fraxinus americana, and Malus.

CAITLIN: One month after each collection date, the class replicated the Primack visual with our twigs.

Slide 19: A similar photo of cut twigs. Written at the top: “Collected March 11, 2021, Final Observation April 8, 2021” There are much bigger leaves on Betula papyrifera, Acer saccharum, Quercus rubra, Fraxinus americana, Quercus palustris, Quercus alba, and Malus

CAITLIN: Here is one month after our March collection date.

Slide 20: Text: “Writing Assignment”

CAITLIN: To put this in context, the major summative assessment of the semester was a literature review. I wanted to use this lab project as a way to model the writing process in miniature. For the winter twig phenology lab, the students wrote a four-paragraph Introduction.

Slide 21: The graphic schedule from Slide 15.

CAITLIN: The narrow scope of the writing assignment reduced the grading load, while offering an opportunity to practice important science writing skills, including synthesizing the literature, identifying knowledge gaps, and clearly stating hypotheses for an ongoing experiment. While this was a lab assignment, I took on the writing grading because I wanted to give students a chance to see my feedback and grading style ahead of their Literature Reviews.

Slide 22: Text: “Reading: Primack et al 2015 From observations to experiments in phenology research: investigating climate change impacts on trees and shrubs using dormant twigs.”

CAITLIN: Abby set up a shared google folder of winter twig papers. Students read the Primack et al 2015 review before the first twig collection lab. [Another citation appears on the slide: “Polgar et al 2013 Drivers of leaf-out phenology and their implications for species invasions: insights from Thoreau’s Concord.] We all read Polgar et al. 2013 before Caroline Polgar zoomed with the class. [More citations appear on the slide: Basler and Korner 2012 Photoperiod sensitivity of bud burst in 14 temperate forest tree species; Dantec et al 2014 Chilling and heat requirements for leaf unfolding in European beech and sessile oak populations at the southern limit of their distribution range; Laube et al 2014 Chilling outweighs photoperiod in preventing precocious spring development; McDonough MacKenzie et al 2020 Low‐cost observations and experiments return a high value in plant phenology research; Menzel et al 2020 Chilling and Forcing From Cut Twigs—How to Simplify Phenological Experiments for Citizen Science] Then, students chose at least three other papers from the folder to read and cite in their writing assignment.

Slide 23: Text: “Hypotheses: Develop at least two hypotheses for the Forest Ecosystems Twig Phenology Project. Use the readings to inform your expectations for this experiment. Look beyond your own twigs to the whole class’ collection of species. For each hypothesis, state your expectations in a declarative sentence. Then, support your reasoning in 2-3 sentences that cite at least one paper.”

CAITLIN: We asked students to submit hypotheses two weeks after the first collection date. This was the text of the assignment presented to students. I gave feedback on the hypotheses and encouraged students to resubmit hypotheses if they were unsatisfied with their grades.

Slide 24: Text: “Outline: Create an outline for a four-paragraph Introduction. Use bullet points and forget about complete sentences. Place the names of five papers (ex: “Primack et al. 2015”) into the outline, noting where you might cite each paper.

The four paragraphs:

• Introduce the BIG question (why study phenology?)

• Give background information (what do we know about phenology?)

• Narrow that background (what do we know from twig experiments?)

• “In This Study” (Identify the knowledge gap, present the experiment, and end with your hypotheses)”

CAITLIN: We asked students to submit an outline one week after their hypotheses. The assignment was very prescriptive. We gave them a lot of scaffolding so that the focus was clearly on synthesizing the literature and using citations to support their points.

Slide 25: A somewhat blurry picture of a rubric [Rubric available upon request].

CAITLIN: Students were given this rubric for their outlines. Again, I encouraged them to resubmit their outline if they were unsatisfied with their grade

Slide 26: Text: “Complete Draft: Submit a completed draft of your four-paragraph introduction. This draft should build on your four-paragraph outline —

• Introduce the BIG question (why study phenology?)

• Give background information (what do we know about phenology)

• Narrow that background (what do we know from twig experiments)

• “In This Study” (Identify the knowledge gap, present the experiment, and end with your hypotheses)

Please cite five papers from the Phenology Literature folder and include a Literature Cited section below your Introduction text.”

CAITLIN: One week after submitting their outlines, they submitted a complete draft. The complete draft was presented as a chance to build out the outline. The instructions were repetitive and straightforward.

Slide 27: A photo of the book Ungrading edited by Susan D. Blum. Text: “Draft Feedback: ‘When comments on papers are accompanied by grades, students disregard our comments — often not even reading them and certainly not using them to improve or learn more deeply.’” The quote is from Susan D. Blum.

CAITLIN: I explained to students in class that I would not grade their drafts. I had read Ungrading over winter break and I was really struck by the finding that “when comments on papers are accompanied by grades, students disregard our comments — often not even reading them and certainly not using them to improve or learn more deeply.” I told the students,“This is a “formative assessment” — “The goal of a formative assessment is to monitor student learning to provide ongoing feedback that can help students identify their strengths and weaknesses and target areas that need work.”” So I wrote extensive comments on the drafts and added a narrative note in the Course Management System, but did not assign a grade to the drafts.

Slide 28: Text: “Polished Draft: Submit a final draft of your four-paragraph introduction. This draft should build on your four-paragraph outline —

• Introduce the BIG question (why study phenology?)

• Give background information (what do we know about phenology)

• Narrow that background (what do we know from twig experiments)

• “In This Study” (Identify the knowledge gap, present the experiment, and end with your hypotheses)

Please cite five papers from the Phenology Literature folder and include a Literature Cited section below your Introduction text.”

CAITLIN: A week later, students submitted a Polished Draft….The language of the assignment was very familiar to everyone at this point...

Slide 29: A slightly fuzzy rubric, very similar to Slide 25.

CAITLIN: The rubric was an extension of the outline rubric, the expectations were very consistent from assignment to assignment. I was so impressed with student responses to my feedback — the grading was such pleasant experience. I felt like I had stumbled into some kind of magic by Ungrading the draft introductions, and this tiny experiment in ungrading has inspired me to think about replacing grades in larger assignments, or potentially across a whole course. The Class Average for the polished draft was 28.44/30, but even more importantly, I felt like everyone was ready to tackle larger and longer writing assignments.

Slide 30: Text: “Successes and Opportunities for Improvement”

CAITLIN: Reflecting on our winter twig lab project with each other and with the students, Abby and I identified our successes and opportunities for improvement.

Slide 31: Text: “Successes:

• Scaffolded writing assignments led to great final products, both in this assignment and in larger assignments later in the semester

• Ungrading worked the drafts improved dramatically

• We got outdoors & into the Arboretum

• Students were interested in the observations (even though they’d forget sometimes)

CAITLIN: First, the structured writing assignments with an ungraded draft were a huge success. I felt like this set a great tone for the larger writing assignments in the class and it established a positive relationship where I was working WITH students to help improve their writing. The polished drafts from this assignment were very strong. As the semester progressed, the students continued to submit great writing AND their polished drafts reflected responsive revising based on feedback from myself or peer reviewers. This lab was also a great introduction to field work in the Colby Arboretum. Students got to practice their tree species identification skills, and learned to navigate campus woodlands, the site of the rest of the semester’s field-based labs. The simple methods of the twig experiment did not require extra equipment and really kept the focus on the research questions. And, even though students occasionally forgot to monitor their twigs, they were engaged in the lab.

Slide 32: Text: “Opportunities for Improvement

• So many (nebulous) Learning Goals

• Monitoring and recording by students was spotty

• We saw phenophases we weren’t monitoring

• We did not formally analyze the data”

CATILIN: Some of our Learning Goals were very broad (“Get comfortable with field and lab methods”) and semi-repetitive (“Place this experiment in the context of phenology research” was its own goal and so was “Identify outstanding questions or knowledge gaps in phenology research”). We need to simplify and streamline these goals. We see opportunities for improvement in the student monitoring system. Some groups consistently failed to record their twigs’ phenology outside of lab — this was obviously extra challenging under COVID restrictions because the labs were not often open. Tracking flowering would be really interesting: we noticed that the maple and the apple twigs bloomed before leaves were formed.We also never analyzed our data. We designed this lab to focus on writing an Introduction and practicing field skills, and by the time we had collected our leaf out data, we had moved on to other labs and forest ecology skills. The “results” visuals that we created conveyed broad patterns, but modelling the chilling units and growing degree days to leaf out for each species was beyond the scope of the lab this year. Future versions of the winter twig project could be expanded to include data analysis and writing subsequent sections of a scientific paper.

Slide 33: Text: “Thank you!” A screenshot of the class in their zoom boxes holding up ‘Congratulations’ signs for the seniors.

CAITLIN: In conclusion, we found this low cost, simple experimental design to be a great addition to our class.

Thank you to all the students in Forest Ecosystems and Dr. Caroline Polgar for being a part of our experiment this year. Please let us know if you implement a winter twig experiment with students — we think there is a huge potential to explore winter chilling hypotheses across latitudinal and environmental gradients with undergraduates.

Thank you!