Leaves still on trees? Blame the cold weather, says ERCA forester

Winter is just a few weeks away but there are still many trees in Windsor with branches that haven't shed their leaves. 

According to Essex Region Conservation Authority forester Robert Davies, cold weather is to blame. 

"What has happened to some of these leaves is they've been unable to form their abscission layer, which usually builds up in the fall and pushes the leaf off the tree," he said.

Davies explained that leaf fall is determined by daylight time, not by cold temperatures, so some trees have already shed their leaves.

"And then there's some more hardy species that hold onto their leaves longer, and those are the ones this year that we're seeing are still holding on to those leaves."

Trees like oak, American beech and ironwood typically retain their leaves over winter, Davies explained, whereas black walnut "is a species that's very susceptible to cold temperatures."

He added that cold weather and an inability to form the abscission layer might even result in some trees keeping their leaves throughout winter. 

Still, while it seem strange to see certain tree species with branches covered in leaves during the late autumn months, Davies said this isn't bad news.

"Essentially that cold weather has blocked off or killed the vessels that carry nutrients back and forth," he said.

Davies said the bigger concern is ice or snow buildup in trees where the leaves haven't been shed. Increased weight and pressure on the branches could result in breakage.

Additionally, Davies explained leaves regenerate from buds, with newer leaves forcing older leaves off branches.

As a result, some residents might have to rake leaves in the spring as well.

"It's a possibility," said Davies.