(Halifax) The typical vibrant reds, oranges and yellows of the trees, marking the arrival of autumn, sometimes appear early in the year, other times not.
The dramatic summer weather, which brought wildfires in some parts of the country and heavy rain in others, is reflected in fall colors across Canada, researchers say.
In Nova Scotia, the summer started with wildfires and ended with thunderstorms, replacing the vibrant hues typical of much of the province this time of year with dull browns.
Mason McDonald, an assistant professor of environmental science and agriculture at Dalhousie University, said the colors he’s seen so far this fall don’t compare to the brilliant reds and oranges Nova Scotians are used to.
“You’ve probably seen a lot of dull colors this year. Even the reds are dull, dark or rusty,” Professor Macdonald said in a recent interview. “A lot of people have talked to me about that this year, especially from southern Nova Scotia.
As nights get longer in fall, trees receive less direct sunlight and the chlorophyll that trees use to absorb sunlight during photosynthesis begins to break down, revealing the natural pigments in leaves.
One of these pigments – anthocyanins – creates the red color of the leaves and requires continuous sunlight until late summer. A drop of anthocyanins won’t harm a tree, McDonald said, and if the next summer is sunny, those vibrant reds will come back into effect.
“This year we’ve had more rain than usual, and at the same time we’ve had dark, gray and overcast days. That’s what happened. We didn’t get the sunlight we normally get. So they can’t make those colors,” MacDonald said.
Early Colors in Ontario
In contrast, Ontario trees started showing their natural pigments earlier than usual.
Photo by Chris Young, Press of Canada
Sean Thomas, a professor of forest ecology at the University of Toronto, says there is evidence to suggest that smoke from wildfires in northern Ontario this summer may have prompted trees to show their colors earlier.
“Smoke from wildfires is a kind of chemical cocktail,” Thomas said.
This cocktail of carbon dioxide, ozone, sulfur dioxide, carbon monoxide and particulate matter “contains traces of chemicals that play a kind of hormonal role with plants,” causing trees to lose leaves prematurely, he explained.
“In our case, we experienced these severe smoke effects in the summer, but this may partly be due to earlier autumn colouration,” Professor Thomas said.
He found a lot of color across much of Ontario this season. He said there is reason to believe that the continuing impacts of climate change will diminish fall colors in the coming years.
There is good reason to believe that climate change will disrupt the normal leaf color we see.
Sean Thomas is a professor of forest ecology at the University of Toronto
He thinks the combination of warmer temperatures and late first frosts will lead to dull fall colors.
He estimates that this effect is greater in large cities, which are generally warmer than rural areas, due to the urban heat island effect, when structures such as roads and buildings absorb and re-emit heat.
If climate change delays the onset of longer, colder nights in places like Toronto, “that’s a recipe for a lot less fall color in the city, and that’s going to be made worse by climate change,” he said. Mr. Thomas said.
In Cape Breton, home of the Celtic Colors International Festival, trees in the area are starting to change color, an event spokesperson said in an interview Thursday. Dave Mahalik heard that the colors were less vibrant in parts of Nova Scotia this year and wondered how they were going to get by.
“But I’m in Sydney and the trees are starting to grow here and they’re looking normal,” he said.
His colleagues told him that colors are vibrant elsewhere on the island, making it a good opportunity for the festival, which will host about 50 concerts in Cape Breton communities.
“I’m very excited and I hope the colors are still as vibrant as ever,” he said.
— with information from Fakiha Baig in Toronto
“Music geek. Coffee lover. Devoted food scholar. Web buff. Passionate internet guru.”
