History

Phenology is one of the oldest areas of environmental science, dating back thousands of years.

Phenological observations have provided indications of the progress of the natural calendar – when seasons begin and change – since pre-agricultural times. The Chinese are thought to have kept the first written records dating back to around 974 B.C. For the past 1200 years, observations of the timing of peak cherry blossoms in Japan have been recorded. Read more about this history and how you can be part of it through Project BudBurst.

Pine warbler
Carl Linnaeus
Image: Wikipedia

The word phenology comes from the Greek words “phaino” (to show or appear) and “logos” (to study). Phenology is one of the oldest branches of environmental science, dating back thousands of years. Observations of phenological events have provided indications of the progress of the natural calendar – when seasons begin and change – since pre-agricultural times.

Many cultures have traditional proverbs and sayings which attempt to forecast future weather and climate using phenological observations: “If oak’s before ash, you’re in for a splash. If ash before oak, you’re in for a soak”. But the indications can be pretty unreliable, as an alternative version of the rhyme shows: “If the oak is out before the ash, ‘Twill be a summer of wet and splash; If the ash is out before the oak, ’Twill be a summer of fire and smoke.” While phenological observations may not let you predict the weather from one season to the next, they can be used to identify climate trends over decades and centuries.

The Chinese are thought to have kept the first written records of phenological observations dating back to around 974 B.C. And for the past 1200 years, the Japanese have recorded observations of the timing of peak cherry blossoms.

In Europe, the Swedish botanist Carolus Linnaeus (1707-1778) systematically recorded flowering times for 18 locations in Sweden over many years. His meticulous notes also recorded the exact climatic conditions when flowering occurred. Linnaeus, and a British landowner, Robert Marsham, share the honor of being considered the ‘fathers’ of modern plant phenology.

Marsham could be considered one of the first citizen scientists in modern times. He was a wealthy landowner who kept systematic records of “Indications of spring” on his estate in England. Marsham’s observations were in the form of dates of the first occurrence of events such as flowering, bud burst, and emergence or flight of an insect. For generations, Marsham’s family maintained records of phenological events over exceptionally long periods of time, eventually ending with the death of Mary Marsham in 1958. The records of the Marsham family showed trends that were observed and related to long-term climate records.

“Keeping records enhances the pleasure of the search and the change of finding order and meaning in these events.”
          - Aldo Leopold, A Sand County Almanac

Aldo Leopold is another prominent figure in early plant phenology and is considered to be a founder of the wildlife management field. In 1949, he penned his best-selling book, A Sand County Almanac, a series of essays about wildlife, conservation, land ethic, and phenology taken from his experiences living and working throughout the United States. Leopold felt strongly that record keeping was important to understanding the ecosystems, plants, and animals he encountered. He wrote, “Keeping records enhances the pleasure of the search and the chance of finding order and meaning in these events.” After Aldo had passed on, his daughter, Nina, picked up where her father left off and began keeping phenological records once again. In 1999, Nina, and others published a paper in the Proceedings of the National Academy of Sciences, entitled “Phenological changes reflect climate change in Wisconsin” based on the phenological observations she and her father had collected all those years.

Left – Thoreau’s journals contained phenological
data observed during the late 1900’s which have
been used to extend existing phenology datasets
collected across the United States.
Right: a portrait of Henry David Thoreau. Photos: Wikipedia

The detailed journals of naturalist and writer, Henry David Thoreau, provide a compelling example of the great contributions that volunteers can make to science. They also provide a unique link between current Project BudBurst data and historic observations which in turn can be used to make important scientific discoveries. Thoreau kept a daily journal of natural history observations from 1851 to 1858. This journal included first flowering date observations for close to 500 plant species around Walden Pond. Several naturalists continued to make observations in the same general area over several other time periods up until 1993. In 2003 phenology scientists Richard Primack, Abraham Miller-Rushing and their collaborators started collecting the same kind of data that was collected in the past, primarily dates of first flowers, and dates of when trees and shrubs leaf out (equivalent to the Project BudBurst first leaf phenophase). Of particular interest, these studies show that plant species vary widely in their ability to change the dates of their phenophase events as weather and climatic conditions change. Interestingly they found that plants in some families have not changed the dates of phenology as much as others, and that these plants tend to be less common now than they were during Thoreau’s time. This suggests that with Project BudBurst data it will be important to see which species are changing their phenology most quickly, and to identify those that are flowering or leafing out on the same dates, regardless of changes in weather or climate.

Much could be learned by doing this kind of analysis with Project BudBurst data since it covers the entire country (not just Walden Pond or Wisconsin) and also includes a broader range of phenophases than what was originally recorded by phenologists of the past. This will allow scientists to identify how different regions of the country, and different species are responding to climate change, and also to determine which are the most important species to watch. By participating in Project BudBurst, you are contributing to this long established history of phenologists. You also join a legion of citizen scientists across the world and through the ages that are helping to understand changes in plants over time.

Top photo: The Aldo Leopold Foundation (www.aldoleopold. org)