Dormant Twigs in Multiple Temperatures

 By Richard B. Primack

 

“Many times I have thought that if the particular tree, commonly an elm, under which I was walking or riding were the only one like it in the country, it would be worth a journey across the continent to see it.” Henry David Thoreau in his Journal.

 

Dormant twig studies have emerged as one of the most effective ways to study the effects of a warming climate on the leafing out and flower times of woody plants. 

On February 5, Selby Vaughn defended an undergraduate honors thesis which used dormant twigs to investigate the effects of a wide range of temperatures on the flowering and leafing times of 12 species of trees and shrubs. 

Photo 1: Selby and committee members Richard Primack, Max Helmberger, and Cheryl Knott.

The thesis was titled: PHENOLOGICAL TRENDS IN THE EFFECTS OF TEMPERATURE ON FLOWERING AND LEAFING OUT TIMES OF WOODY PLANTS USING A DORMANT TWIG EXPERIMENT.

Photo 2: Twigs of 12 species being evaluated for stages of flowering and leafing out.

 

As predicted, the tree and shrub species flowered and leafed out earlier in warmer temperature conditions. The study was noteworthy in its use of a wider variety of temperatures than any previous dormant twig study, which will help to determine if species responses to temperature are linear rather than curvilinear.