Phenology

The force that through the green fuse drives the flower
Drives my green age; that blasts the roots of trees
Is my destroyer.
And I am dumb to tell the crooked rose
My youth is bent by the same wintry fever.

The sun is the force that drives all in its complex dance through the year. The green fuse traps the sun's energy to produce the flower. The sun's energy creates the weather from a local breeze to a full blown hurricane that blasts the root. Phenology "is the study of periodic plant and animal life cycle events and how these are influenced by seasonal and interannual variations in climate." Phenology attempts to transcribe the music of the sun's dance into something we can understand. If we can't tell the rose about it, we can use this transcription as stewards of the earth.

In a world where genetics and biochemistry get all the headlines, phenology may be the most important biological science of all. How do we translate the sun's story into something we can understand? One way is to simply measure the amount of light on a patch of ground and record what happens there. More useful is the concept of growing degree days. Plant growth around here is thought to start somewhere between 45 and 55 degrees Fahrenheit so 50° has been chosen as a baseline. To calculate GDD you simply take the high and low temperature for the day and average it. If the high was 80° and the low was 60° then the average for the day was 70°. Subtract 50 from the average, and you get 20 Growing Degree Days for that date. Total the GDD's then match the number with events like bud opening or full flowering of a specific plant, and soon you have a record of how the sun's energy effects plant life. You can then expand out to match the lifestyles of the bugs that eat the plants, and the animals that eat the bugs. While it's fun to play Carnac the Magician and predict when lilacs will bloom in your neighbor's backyard, the real use of this method is in integrated pest management (IPM) systems. IPM attempts to cut down on pesticide use and use the mildest possible pesticides, by striking at a pest at its weakest moment. Using phenology you can predict the best time to spray your fruit trees to kill gypsy moth caterpillars before they do extensive damage.

Lilacs have bloomed in doorways long before Walt Whitman wrote about them, and dates of bloom were recorded in farmer's diaries. Collect this data and you can see how our irresponsible acts have changed the music of the solar dance. Birds can't count GDD, but the ones that showed up when the total GDD had their prey species at a maximum survived better than those that didn't so over generations average arrival dates were keyed to average GDD. Change the insect maxima by warming the planet and you have added dissonance to the dance of life that can lead to species extinction.

All this is on my mind today as I meet with an intern from Stonehill who will begin to design a floral calendar for us. It's a first step towards real phenology. Thanks again to Ali and Caitlyn who put me on this path many years ago.