autumn leaves colors change drought stress trees

Fall 2022 will not be like the previous ones. At least when it comes to so-called foliage, the phenomenon that gives rise to the amazing color spectrum of leaves falling from trees and shrubs.

The drought that hit winter 2021-2022 and last summer so hard would cause a change in the way fall foliage presents itself to our gaze. Typically, in the fall, before the leaves drop, each takes on a rusty brown, amber, bright yellow, brown, or fiery red hue, the Washington Post notes in a report. However, this year’s fall landscape “may be duller than usual in many places.” And this is due to “an exceptionally hot and dry summer, which put the trees to the test”.

Photo Ansa / EPA CJ Gunther

Leaves, plant solar panels

Nature suffers. The result is that heat and drought can “stagger leaf senescence” temporally. Essentially, it’s likely, Agi says, that fall colors will have more yellow and brown colors in geographic areas of Earth most affected by drought. And among these, in Europe, there is also Italy. Either way, argues The Washington Post, “people can still find pockets of bright color, especially in the wetter areas” of a territory. After all, the leaves change color because they are like little solar panels for a plant. Their task “is to absorb sunlight and produce food, or glucose, by photosynthesis,” is the technical and scientific explanation.

In addition, during the fall, the days get shorter. This results in less sun for the plants and the leaves stop producing food. Chlorophyll breaks down, revealing different colors, but “for best fall color, temperature and amount of humidity are the main influencing causes. Besides sunshine duration and angle,” wrote Kyle Costner, creator of The Foliage Report, a site dedicated to the subject. The thing is, when the leaves start taking too much energy from the tree, the detachment process begins, says Alberto Ferrigolo from Agi.

Andy Finton of the Nature Conservancy, an American environmental association in Massachusetts. Twitter pic @AndyFinton

Why trees lose their leaves

The loss of leaves helps trees retain water during the winter. And use less energy to stay alive. However, “a severe drought has accelerated leaf fall this year. Stressed trees are no longer able to keep them attached to branches. So they start falling earlier,” says Andy Finton, a conservation ecologist at the Nature Conservancy in Massachusetts.

Autumn, fewer shades of color

And that means they “turn brown before they have a chance to break down their green colors to expose yellow and orange. And before they had a chance to develop bright red colors for species like red maple and sumac,” Finton wrote. In eastern Massachusetts, for example, “we’re seeing less fall color and some leaves are still green,” but “some trees have leaves that wilted before they even had a chance to turn the right color.” , Finton noted. Another effect of climate change, of which there is no turning back but only a slowing down of the race.

Autumn leaves in Italy. Photo Twitter @Lucianone73