Have you noticed that the fall leaves are extra colourful in Ontario this year? Well, you’re not the only one. According to experts, the autumn hues are particularly bright this year because of certain weather patterns.
University of Toronto professor of forest ecology Sean Thomas explains to CTV News why leaves were more vibrant this year.
“It has [been] probably the best in some years,” Thomas said. The potent colours are a result of lower temperatures with sufficient rainfall, but no frost. While drier, warmer weather causes dull colours in the changing leaves, moist, cold temperatures make them brighter.
“Cold snaps in September and early October are kind of key to triggering that physiological process,” he continued. “Last year was kind of remarkably dull. If you recall, we had a warm and somewhat dry fall.”
Western University assistant professor of forest ecology Ben Rubin added that leaves change colours due to three factors: the species, the length of a day and the weather.
While the species and the length of a day are static, the weather is the only factor that varies year-over-year.
Rubin went on to explain that there are three chemicals that influence a tree’s colours. The first of which is chlorophyll, which gives leaves their green hue in the growing season. As the weather begins to get colder and the days get shorter, two other chemicals step in and become more visible: carotenoids and anthocyanins, which give leaves their yellow and red shades.
The amount of anthocyanin production is directly linked to high sugar concentration and bright light in leaves, but this amount varies directly as a result of the weather.
“The amount [of anthocyanin] produced varies among tree species and depends on the weather,” Rubin explained. “In general, sunny days and cool but not freezing nights result in higher production and, therefore, brighter colours.”
Depending on what the weather will be like in the coming days, these bright fall colours could last anywhere from one to several weeks. But, since Ontario has had a slew of winds and storms lately, there will likely be an early end to the stunning fall hues.
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