(The fifth in a series on climate change in the county)
GHENT—Phenology is the study of the timing of nature’s seasonal life-cycle events, such as the emergence of leaves on trees, the blooming of flowers or the migration patterns of birds.
Following a trail of clues, Dr. Conrad Vispo of Hawthorne Valley’s Farmscape Ecology Program (FEP) discovered a unique ecological treasure trove of phenology records created by secondary schools (then called “academies”) throughout New York State during the nineteenth century.
He collaborated with a team led by Dr. Kerissa Battle of the Community Greenways Collaborative and the New York Phenology Project to compare the more-than-century-old data to twenty-first century records. The contemporary records were made by citizen scientists throughout the state working with the New York Phenology Project, a regional affiliate of the USA National Phenology Network.
In a peer-reviewed study recently published in the Journal of Ecology, the team put forward a series of observations about the dramatic, local climate-driven shifts documented by this unparalleled database. Over time, various site-specific phenology studies have been made. For example, Thoreau collected such data for years at Walden Pond—a single location; a comparison with current Walden Pond data has now been undertaken by Dr. Richard Primack of Boston University. But, according to the Journal of Ecology article “no other North American data set provides a multi-decade, multi-site standardized collection of phenological data from the early industrial period.”
Starting in 2014 Dr. Vispo began noticing occasional references to “some apparent reservoir of historical phenology data.” Following those leads, he found that the Regents of New York State directed the academies that it supervised to collect meteorological and phenological data according to specific protocols, across nearly every county of the state as an aid to agriculture. Records were kept and summarized by the network from 1826-1871.
They may be viewed on the website of Hathi Trust, http://catalog.hathitrust.org/Record/008961546 and may be searched at https://www.hvfarmscape.org/cms/
The network collected paired phenology and weather data at more than 90 sites. In Columbia County, the Hudson, Kinderhook and Spencertown academies, as well as schools in Chatham and New Lebanon, participated, having been given some tools—a New Lebanon-made Kendall thermometer and rain gauge—to assist them.
The Farmscape Ecology Program group digitized the more than 12,000 Regents records and found that there were dozens of species in common between the historical data and the contemporary records collected by the New York Phenology Project volunteers.
In the Journal of Ecology study, the authors, including FEP’s Anna Duhon and Conrad Vispo, focused on the first flower date and first leaf date of various plant and tree species, in the context of the contemporaneous weather data.
In general, they found that January-April temperatures warmed substantially statewide between 1826 (the earliest date of study) and 2017 (the most recent). On average, first flower and leaf dates both advanced significantly in that same time period: first flower date by 10.6 days and first leaf date by 19.0 days. The January-April temperature was the strongest factor, of those studied, in that acceleration.
Within those general observations were a number of more specific findings. For example, both the leafing and flowering dates were more advanced by over 3 days in urban, than in rural, settings. Insect-pollinated trees were more sensitive to temperature than wind-pollinated trees, with the first flowering dates of the former advancing 27.4 days vs 8.1 days for the latter.
Certain species were seen to be largely unaffected by temperature change, while others were deeply affected. American Elm are now flowering over 25 days earlier than in the 1800s in hardiness zone 5 (comprising most of Columbia County); Red Maple is flowering nearly 19 days earlier.
According to FEP’s Ms. Duhon, some of these shifts may result in “mismatches” that profoundly affect other species. For example, if an insect (say, a honeybee) that depends on a particular flower’s nectar (say, that of a Red Maple) does not adjust its hatching to cycle to the flower’s earlier flowering the insect population may be affected.
A bird that migrates because of daylight cues, not temperature, may arrive out of sync with the food source on which it relies which has produced weeks sooner. Earlier leafing in forests may affect the growth of forest understory, shading it from sunlight earlier in the season.
All these effects, underscoring the interconnectedness of our natural surroundings, will be subjects of further study.
As Ms. Duhon notes, there is a “wonderfully meditative quality to tuning in to the seasonal changes around us, even in our backyards.” The New York Phenology Project creates opportunities for such backyard studies.
In a similar vein the Farmscape Ecology Program and the Martin Van Buren National Historic Site (MVB), located in Kinderhook, have created a “phenology trail.” Certain trees and plants have been marked for regular “visits,” and observations as to leafing and flowering are recorded by park staff following a protocol that ensures uniformity of data. As the MVB website says, a pear tree observed in 2021 flowered two weeks earlier than the first flowering observed in a pear tree in Kinderhook in 1830.
The study is entitled “Citizen science across two centuries reveals phenological change among plant species and functional groups in the Northeastern US,” and can be accessed for free at https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/1365-2745.13926 . Its authors, in addition to Dr. Vispo and Ms. Duhon of FEP, are Dr. Kerissa Battle (the lead author) and Lilas Armstrong-Davies of Community Greenways Collaborative, Inc. of Bearsville, NY, in the Catskills, Dr. Todd Rosenstiel and Dr. Catherine de Rivera, of Portland (Oregon) State University, and Dr. Theresa Crimmins, of the USA National Phenology Network.
