Ecological Society of America 2020
Transcript for A 19th century naturalist and a 20th century hunting guide reveal phenological mismatches in temperate deciduous ecosystems.
Slide 1: A photograph of a child walking on the beach at Walden Pond in early spring. Text: A 19th century naturalist and a 20th century hunting guide reveal phenological mismatches in temperate deciduous ecosystems. Caitlin McDonough MacKenzie, Colby College, cnmcdono@colby.edu, twitter handle: @CaitlinInMaine.
CAITLIN: Aww cute! Walden Pond. Spoiler alert on the talk title [an animated scribbled now covered the top line of the title text “A 19th century naturalist and a 20th century hunting guide reveal”]. Was Thoreau the best or worst social distancer?
Slide 2: The same photo of Walden pond, with title text that now reads “Phenological mismatches in temperate deciduous forests.” A video player is set in the middle of the slide; in the video Caitlin sits under a deciduous forest and speaks to the camera to introduce herself.
CAITLIN: This talk is designed to double as a mini-lecture for an intro ecology course. Shout out to my Colby College students who are watching this in mid-September for our phenological mismatch lab. Go mules! If you are interested in incorporating this video into your undergraduate class, please reach out & I’ll be happy to share it outside of the ESA platform or “visit” your course as a video-guest Before I begin, I would like to acknowledge that this research takes place in the homeland of the Wabanaki, Pawtucket, and Lenape people.*
Slide 3: White text on a black background “Phenology is the timing of seasonal biological events.” As Caitlin speaks, line drawings appear on the screen: a jar of maple syrup, a downhill skier, and a pumpkin.
CAITLIN: Phenology is the timing of seasonal biological events. Usually, when I give this kind of talk, I use maple syrup, spring skiing, or pumpkin soup as examples of the annual events that have strong seasonal ties for me — the phenological events in my typical year.
Slide 4: White text on a black background “Phenology is the timing of seasonal biological events.” As Caitlin speaks, line drawings appear on the screen: a laptop, a latte, and a Chaco sandal.
CAITLIN: For the past decade, nearly every August, I’ve found myself editing powerpoint slides, trying to find a local coffee shop that serves strong espresso close to the conference center, and comparing Chaco tans with my friends and colleagues. Now that I am recording this talk in July, at home, the shift in conference-phenology has me thrown!
Slide 5: A photo of sheep’s laurel with unopened flower buds and a photo of sheep’s laurel in bloom. Underneath the photos the word “phenology.”
CAITLIN: In the natural world, I study phenology in plants: the timing of leaf out and flowering. These events are shifting earlier in response to warming spring temperatures.
Slide 6: White text on a black background: “Phenology - the timing of seasonal activities of animals and plants — is perhaps the simplest process in which to track changes in the ecology of species in response to climate change. Intergovernmental Panel on Climate Change, 2007”
CAITLIN: Shifts in phenology have been recognized as an important indicator of climate change for over two decades.
Slide 7: White text on a black background: “what do climate change-induced shifts in phenology mean for interactions between an organism & its biotic and abiotic environment?” As Caitlin speaks, line drawings appear on the screen: a leaf, snowflakes, a leaf, a ladybug, and a bird
CAITLIN: As ecologists we care about the impacts of shifts in phenology. Ecology is the study of how organisms interact with their environments and with one other — so, what do climate change-induced shifts in phenology mean for interactions between an organism & its biotic and abiotic environment? When we talk about ABIOTIC interactions [underline the text “abiotic” on the screen] a good example is: Plants that shift to earlier leaf out may be in danger of suffering from late season frosts. [leaf and snowflakes line drawing appear.] When we talk about BIOTIC interactions [underline the text “biotic” on the screen], we’re talking about how shifts in phenology have the potential to change species interactions with each other. This is phenological asynchrony or phenological mismatch. [leaf, ladybug, and bird line drawings appear.]
Slide 8: White text on a black background: “It is commonly thought that warming will lead to changes in synchrony. These changes are expected to be prevalent because (i) temperature is an important phenological cue for many taxonomic groups, (ii) the temperature sensitivity of the phenology of interacting species can differ and, (iii) global temperatures have increased, on average, by 0.85 °C since 1880. Kharouba et al. Global shifts in the phenological synchrony of species interactions over recent decades.”
CAITLIN: A recent meta-analysis of phenological mismatch explains: It is commonly thought that warming will lead to changes in synchrony. These changes are expected to be prevalent because (i) temperature is an important phenological cue for many taxonomic groups, (ii) the temperature sensitivity of the phenology of interacting species can differ and, (iii) global temperatures have increased, on average, by 0.85 °C since 1880.
Slide 9: Black screen, empty at first, fills with line drawings as Caitlin introduces the four examples.
CAITLIN: Most examples of phenological mismatch in the scientific literature center on trophic interactions — aka when is my food ready to eat? We see this in… Migratory birds and lilacs [line drawings of a lilac and a bird appear over the text “Marra et al. 2005 The influence of climate on the timing and rate of spring migration.”] Migratory birds and green up [line drawings of eBird on a tablet and an NDVI curve appear over the text “Mayor et al. 2017 Increasing phenological asynchrony between spring green up and arrival of migratory birds.] Butterflies and nectar-producing plants [line drawings of a butterfly and a thistle appear over the text “Kharouba and Vellend 2015 Flowering time of butterfly nectar food plants is more sensitive to temperature than the timing of butterfly adult flight.] Caribou and the plants that emerge at their calving grounds [line drawings of lichen and caribou appear over the text Post and Forchhammer 2008 Climate change reduces reproductive success of an Arctic herbivore through trophic mismatch.]
Slide 10: White text on black background: “How do you tell the difference between long-term anthropogenically-induced phenological mismatch and stochastic annual fluctuations in species interactions?”
CAITLIN: However, finding and studying phenological mismatch caused by climate change is not easy! How do you tell the difference between long-term anthropogenically-induced phenological mismatch and normal, run-of-the-mill annual fluctuations in species interactions?
Slide 11: White text on black background: “Phenological mismatch hidden in natural history archives” with line drawings of Thoreau, leaves, flowers, and a journal open to a blank page with a pencil.
CAITLIN: One strategy is to leverage long-term datasets found in natural history archives. Complete long-term records of leaf-out, flowering, and migratory bird phenology for a single location are rare; few naturalists consistently noted these events over long time periods and even fewer had their diaries archived.
Slide 12: White text on a black background: “L. S. Quackenbush” over a page from Quackenbush’s journal listing the order of trees leafing out in spring 1941, a line drawing of the state of Maine pointing out the location of the town of Oxbow in the northernmost county, and a photograph of Caitlin and two coauthors standing in front of Quackenbush’s barn in Oxbow, Maine.
CAITLIN: In the mid-20th century, a hunting guide named L.S. Quackenbush in Oxbow, Maine, kept detailed journals of the annual dates of first leaf-out, first flowering, and the earliest spring sightings of migratory birds. Quackenbush carefully recorded daily notes and observations from his walks through rural Oxbow in his journal. He was not a formally trained scientist, but his consistent observations and detailed notes are an incredible resource! Here I am standing with two coauthors in front of Quackenbush’s barn.
Slide 13: Three pages from Quackenbush’s journal showing order of open flowers in 1945, order of arrival of birds spring 1947, and trees - order of leafing out in spring 1941. Next to each page there is a line drawing of a lilac, a bird, or a pair of birch leaves.
CAITLIN: The historical data captured in the Quackenbush journals from 1940 to 1959, along with historical temperature data from a weather station in nearby Presque Isle, Maine, allows us to explore phenological sensitivity of birds, trees, and flowers in the temperate deciduous and mixed conifer forests of northern Maine.
Slide 14: A figure of mean temperature and dates of leaf out and flowering with tree and tulip emojis for scatter plot points Text: “McDonough MacKenzie et al. 2019 Advancing leaf out and flowering phenology is not matched by migratory bird arrivals recorded in a hunting guide’s journal in Aroostook County, Maine.”
CAITLIN: We found earlier leaf out and flowering in warmer years. On the x-axis April temperatures run from cooler to warmer [pointer runs across the x-axis on the screen]. On the y-axis dates are arranged from early May to late June [pointer runs across the y-axis on the screen]. Each tree emoji [pointer highlights a tree emoji on the graph] represents the mean leaf out date across 10 species for a single year; each tulip emoji [pointer highlights a tulip emoji on the graph] represents mean flowering date across 15 species for a single year.
Slide 15: The same figure as in Slide 14, but with the addition of bird emojis.
CAITLIN: However, we found no significant relationship between migratory bird arrival and spring temperatures. Here each bird emoji [pointer highlights a bird emoji on the graph] represents the mean arrival date across 8 species for a single year.
Slide 16: White text on a black background: “warmer springs lead to advancing leaf-out and flowering, but no changes in migratory bird arrivals.” Line drawings appear as Caitlin speaks, a tree, two wildflowers, and a bird.
CAITLIN: The asynchrony found in Oxbow — where warmer springs lead to advancing leaf-out and flowering, but no changes in migratory bird arrivals — has the potential to create trophic mismatches and disrupt ecological relationships.
Slide 17: White text on a black background: “can two organisms in the same trophic level experience phenological mismatch?
CAITLIN: What about non-trophic interactions? Instead of a plant and the organism that eats it, can two organisms in the same trophic level experience phenological mismatch?
Slide 18: a photograph looking up at a canopy of bare deciduous tree branches. Photo by David DeHetre.
CAITLIN: In deciduous forests, the plant growth in the understory is strongly limited by light availability, which is controlled by the overstory canopy. The timing of canopy leaf out in the spring determines the end of the “high light” season for understory species.
Slide 19: a photograph looking up at a canopy of fully-leafed out deciduous trees. Photo by Robert Postma
CAITLIN: Many forest wildflowers emerge and flower in the early spring to exploit this critical period of high light, reaching maximum photosynthetic rates that abruptly decline as the overstory trees leaf out and the canopy closes.
Slide 20: White text on a black background: “Is the length of the “high light” period changing? Are understory wildflowers and overstory trees experiencing phenological mismatch? And how will fewer “high light” days in the spring impact seasonal carbon gain, reproduction and long-term survival of ecologically and culturally important wildflower species?”
CAITLIN: We asked: Is the length of the “high light” period changing? Are understory wildflowers and overstory trees experiencing phenological mismatch? And how will fewer “high light” days in the spring impact seasonal carbon gain, reproduction and long-term survival of ecologically and culturally important wildflower species?
Slide 21: White text on black background: “Henry David Thoreau” above a photo of a child next to the Thoreau statue at Walden Pond and line drawings of leaves, a tree, and three wildflowers.
CAITLIN: To answer the first two questions, we combined data from Henry David Thoreau’s observations of first leaf out and flowering in Concord, Massachusetts during the 1850s, Thoreau super-fan Alfred Hosmer’s parallel observations in late 19th century Concord, and the Primack lab’s 21st century re-surveys of leaf out and flowering phenology for the same species in Concord today. We also used historical temperature data from the long-term records at Blue Hills Observatory.
Slides 22: A set of two graphs showing mean April temperatures on the x-axis and first flower date (top graph) and first leaf date (bottom graph). In both graphs, warmer April temperatures are related to earlier phenology. Next to the flower graph there is a photo of a flower and the handwritten text “-2.2 d/C”; Next to the leaf graph there is a photo of Caitlin under a blooming cherry tree and the handwritten text “-4.4d/C.”
CAITLIN: Across the last 170 years, trees have leafed out about 4.4 days earlier for 1C increase in mean spring temps, while wildflowers flowered 2.2 days earlier per 1C. Trees in Concord are leafing out nearly two weeks earlier now than in Thoreau’s time, but wildflowers are flowering less than a week earlier. So the length of the “high light” period in the understory is shrinking -— wildflowers today have lost a week of high light compared to Thoreau’s time.
Slide 23: White text on black background: “how will fewer “high light” days in the spring impact seasonal carbon gain, reproduction and long-term survival of ecologically and culturally important wildflower species?” Underneath, an illustration by Bonnie McGill with the hand-written paper title “Phenological mismatch with trees reduces wildflower carbon budgets by Mason Heberling, Caitlin McDonough MacKenzie, Jason Fridley, Susan Kalisz, Richard Primack” with cartoon sketches of the faces of each of the coauthors.
CAITLIN: This brings us back to our last question. To address how fewer “high light” days in the spring will impact seasonal carbon gain, Richard Primack and I partnered with Mason Heberling, Susan Kalisz, and Jason Fridley.
Slide 24: A series of eight figures showing daily carbon gain (y axis) over the course of the year (x axis: March-Jan) for eight different understory species. Text: “Heberling et al. 2019 Carbon gain phenological of spring-flowering perennials in a deciduous forest indicate a novel niche for a widespread invader.”
CAITLIN: Mason’s research on wildflower carbon gains over the growing season was based in Pittsburgh, where he measured photosynthesis and modeled carbon gain for wildflowers in a common garden to assess the relative importance of spring, summer, and autumn to species-level carbon budgets. In other words, Mason kept detailed weekly food logs for understory wildflower species, but instead of a nutrition app, these were recorded by a Li Cor instrument. Each figure shows the daily carbon gain for a wildflower species [pointer highlights the curve from high daily carbon gain in spring to low daily carbon gain in the summer] over the course of the year. The grey rectangles [a hand-drawn rectangle highlights the shaded grey rectangles on each graph] represent the shady summer under a closed canopy.
Slide 25: White text on black background: “Compared to Thoreau’s time, understory wildflowers today have lost a week of high light time. By 2080, the high light period could shrink by another 6-12 days.”
CAITLIN: We used his model to simulate seasonal carbon gain under different “high light” periods.
Slide 26: A figure of the modeled relationship between changes in spring length and changes in annual carbon gain. Text: “Heberling and McDonough MacKenzie et al. 2019 Phenological mismatch with trees reduced wildflower carbon budgets.”
CAITLIN: This figure shows change in the length of the “high light” period on the x-axis [pointer highlights the bottom x-axis], which matches changes in spring temperature [pointer highlights the top x-axis]. On the y-axis, the change in annual carbon gain is centered on today’s carbon budgets [pointer highlights y-axis]. Positive values represent larger annual carbon gains than today, while negative values represent smaller annual carbon gains. Based on this model, we estimate that wildflowers in Concord had larger annual carbon budget in Thoreau’s time by 6.2-8.0% [pointer highlights this point on the figure]. By 2080, we estimate that mean annual carbon budgets of wildflowers will be 5.7-12.6% lower than today [pointer highlights these points on the figure]. To see more on Mason’s work and the future of this project, check out his poster in PS-41 Phenology!
Slide 27: White text on a black background: “Natural history records are a powerful resource. Long-term records can identify phenological mismatch through detailed observations of interacting species.”
CAITLIN: In these case studies, a19th century naturalist and a 20th century hunting guide reveal potential phenological mismatches in temperate deciduous ecosystems! Natural history records are a powerful resource. Long-term records can identify phenological mismatch through detailed observations of interacting species. Ecologists owe a debt to the families, librarians, and archivists who have preserved and cared for these records. Of course, measuring the ecological effects of decoupling these interactions is still challenging! For example, with the shade research, we needed Thoreau’s records *and* experimental field methods to tell the whole story! In our case, this was a totally serendipitous connection where two friends & professors at different universities (Richard Primack and Jason Fridley) realized their recently fledged PhD students (me and Mason) were working complimentary side projects leftover from our times in their labs. Mason (the first author) and I (the second author) didn’t even meet in person until after the paper was published! Finally, it’s important to reflect on the sources of historical ecological data: whose journals get archived? Thoreau and Quackenbush were not unique in their attention to seasonal changes; they were special because their journals were archived. This is a privilege that was not extended to many white women or people of color.
Slide 28: A return to the first photograph of a child at the beach at Walden Pond. Text: “Thank you! Acadia National Park, College of the Atlantic, Team Quackenbush: Jason Johnston, Abe MillerpRushing, Bill Sheehan, Bob Pinette, Walden Pond in Concord, MA, Trillium Trail in Pittsburgh, PA, Bonnie McGill.”
CAITLIN: Thank you so much for watching this virtual talk! Hope to compare Chaco tans with you next year.
Slide 29: POST-CREDITS PRODUCTION LOGO/VANITY CARD: “Mara’s Mom Productions” written over a black and white shot of Caitlin reading her lines under a tree.
OFF-SCREEN CHILD: Mom! Mommy!
CAITLIN: Significant eco-[breaking] ecological impacts. Oh my! [Laughing]
*My land acknowledgement was incomplete. Thank you to Dr. Bonnie McGill for correcting me & sharing this information: The city of Pittsburgh, PA are located within the ancestral and unceded homelands of the Monongahela people (autonym unknown), the Seneca (O-non-dowa-gah) people--one of the Six Nations of the Haudenosaunee--and the Lenape (Lenni-Lenape or Delaware) people. The Wyandot (Wandat) and Shawnee (Shaawanwaki) also spent time in this region in the 1700s and 1800s. The early ancestral homelands of the Osage Nation (Wahzhazhe) also include the Ohio River Valley (the Osage had migrated to what is now the Missouri area before European settler-colonialism).
The Monongahela disappeared around 1650, most likely as a direct result of colonial violence. The Seneca (today: Seneca-Cayuga Nation), Lenape (today: Delaware Nation and Delaware Tribe of Indians), Wyandot (today: Wyandotte Nation), and Shawnee (today: Absentee-Shawnee Tribe of Indians of Oklahoma, Eastern Shawnee Tribe of Oklahoma, and Shawnee Tribe) also faced colonial violence, and were separately, forcibly removed to what is now Oklahoma, where many of their descendants live today. This dispossession of their land was in violation of multiple treaties and in accordance with the Indian Removal Act of 1830 (ethnic cleansing). A related group of Seneca are the Seneca Nation of Indians who today live in Salamanca, New York.
You can learn more about the tribes and nations above by visiting their museums including the: Seneca-Iroquois National Museum in Salamanca, NY; Shawnee Tribe Cultural Center in Miami, OK; Eastern Tribe of Shawnee’s Betty Jane Holden Admussen Tribal Museum in Wyandotte, OK; Osage Nation Museum in Pawhuska, OK; the Wyandotte Nation Cultural Center and Museum in Wyandotte, OK; the Museum of Indian Culture in Allentown, PA (in partnership with the Delaware Nation). To learn more about the Wabanaki and Pawtucket tribes and nations, I highly recommend the Abbe Museum in Bar Harbor, ME and Historic Patuxet in Plymouth, MA.