UMF in the News: Drew Barton, forest and fire ecologist and UMF professor of biology, shares some thoughts on early fall color as it begins to show across western Maine

As reported in the Sun Journal, fall colors are beginning to spread across western Maine, with red maples, yellowing hardwoods and other early-changing trees standing out against forests that remain largely green.

Drew Barton, a forest and fire ecologist, science writer and University of Maine at Farmington professor of biology, said some of the variation is simply part of the normal progression of fall.

The shortening length of daylight is the primary trigger, he said. Leaves use photoperiod, or the amount of daylight they receive, as a seasonal calendar, but different species respond to that signal at different times.

Ash trees tend to change relatively early, taking on a subtle purple color before dropping their leaves. Red maples also change early and can produce some of the most noticeable reds of the beginning foliage season.

Oaks generally stay green longer before turning brown or brownish red, Barton said, while birches fall closer to the middle of the progression.

The timing can vary even among trees of the same species or between branches on a single tree. Barton said temperature, moisture, genetics and the amount of stress experienced by a tree or individual branch can all affect when leaves begin changing.