After a summer of drought, extreme heat, and a surge in tree-destroying insects, the changing colours in Ontario’s forests may not be quite as vibrant this fall.
Matt Logan, an arborist and a co-owner of Logan Tree Experts in the Kawartha Region, says that given the curveballs thrown at tree populations this year, it’s difficult to predict how changes will present. “It’s been such an up and down year… I feel like we’re kind of rolling the dice,” Logan says.
After the June drought throughout much of Ontario, there was an unprecedented infestation of the Lymantria dispar dispar (LDD) moth, an insect that feasts on many of the province’s most common tree species, including apple, oak, and birch. This led to rapid defoliation, with many trees shedding their leaves completely; in Logan’s area, up to 70 per cent of trees were defoliated. Coupled with the stressor of extreme heat, there may simply be fewer trees able to complete the cycle of changing colours, he explains.
Although these signs point to a shorter, less vibrant fall foliage season, Logan says that many trees will be able to bounce back. Some parts of Ontario have had a wet, relatively cooler autumn thus far, providing favourable conditions for the change to take place. “It’s always a point of interest to see—these trees were really stressed, how are they going to act now?” Logan says. “They’re going to pick their own times [to change colour], and it depends on how they deal with energy allotment.”
Many trees change colour in the fall when reduced sunlight and heat causes a drop in chlorophyll, a chemical that gives leaves their green tones and is central to photosynthesis, the process plants use to create and store energy. Logan says if some trees were able to gather enough energy in late summer, they may begin to store it, showing their colours a little earlier than usual. On the other hand, some may continue to photosynthesize, meaning they won’t show off their colours for as long. “So much of it is dictated by temperature conditions, so some trees may still be needing energy, and it’s just not going to happen because we’re getting that cooler weather,” he says.
Logan points out that, just like for many people, it’s been a tough year for trees in Ontario and the rest of the country. “I wouldn’t blame the trees if they decided not to put on a show this year,” he says. “Like most of us in the last year and a half, it’s been a tough go… I think some may just want to crawl into a hole and wait for next year.”
If you’re eager to get out and take in the fall foliage before this happens, be sure to check out our recommendations on the best places around the province to see the colours while they last.