In terms of cell biology, it’s like the chlorophyll jailer fell asleep and the colours escaped, painting trees and plants across B.C. with crimson, gold, and purple.
“I’ve never taken so many photos of leaves,” notes Capilano University biology instructor Michael Kiraly.
Originally from Ontario, Kiraly remembers taking late September/early October treks to Algonquin Park as the sugar maple trees burst into orange and red.
“When I moved to British Columbia I missed them,” he says of those days and those colours.
But this fall has been different, as even bins of yard trimmings look like fireworks displays.
The reason for the change began in spring, Kiraly notes.
In March, April and May of 2016, Vancouver received 236 millimetres of rain. In 2017, it got 442 mm. The wet spring served as the herald for a long, hot summer. And while the heat wasn’t great for beach barbecues, it was ideal for vegetation.
“They had all the ingredients they need to kick into overdrive and start manufacturing their food source to get the tree through the winter,” Kiraly says.
Much like the high-ranking wolves eats before the rest of the pack, chlorophyll enjoys the bounty of water, sunlight, and carbon dioxide while other pigments remain invisible.
But as the temperature fluctuates between warm days and cool night, the chlorophyll starts to degrade. And when that happens, “a number of the other pigments become apparent,” Kiraly says.
Carotenoids provide the rich orange colours. The yellows and golds are the result of xanthophyll. Anthocyanin is the reason we see the “real cool, purpley colours,” Kiraly says.
There’s a brief period after fall’s chill fills the air but before the autumn wind plunders the trees when a layer of tissue grows around the base of each leaf. That abscission layer cuts the leaf off from the rest of the tree, Kiraly explains, allowing those invisible pigments to emerge and arrest the eye.
In his poem, The Glory of the Garden, Rudyard Kipling wrote that “some can pot begonias and some can bud a rose, And some are hardly fit to trust with anything that grows.”
But this year’s long growing season has allowed just about every gardener to ply their craft with amazing results.
There was a recent news story about a farmer attempting to grow bananas and papayas at his Blyth, Ontario farm as well as an account of an Abbotsford man growing bananas in his backyard, Kiraly notes.
“There’s a Japanese maple outside my window that is a scarlet red, it’s beautiful.”
But while the growing season has been long and beautiful, the bright colours should perhaps also serve as a warning sign, Kiraly suggests.
The trend of greater temperature variation is a byproduct of global climate change, Kiraly explains.
“Things are going to get more volatile. And it’s this volatility and this rapid change in temperature that triggers the leaves.”
While the colours of 2017 seem like an aberration today, Kiraly suggests the change is a response to climate patterns that may become more common.
It’s something he encourages people to read about.
“This is biochemistry and cell biology,” he said. “It’s a lot of fun understanding how things work.”