Tree shedding bark

Q: I've noticed that there seems to be so much bark on the sidewalks. I assume the heat wave has made the bark come off early.

What effects will this have on the trees - if any?

A: You don't mention what type of tree(s) you've noticed the shedding bark coming from, but I'm going to guess you are referring to sycamores or London planetrees as they have very obvious exfoliating bark.

Sycamores and planetrees are infamous for having large plates or sheets of bark fall off every year, and the amount will vary from year to year.

The bark exfoliates because the tree (branches and trunk alike) increases in diameter faster that the tree can keep up with, so as the tree increases in diameter, the bark gets shed.

The extra bark shed this year may in fact be due to the dry weather. The connection between the dead outer bark and the underlying periderm layer may have been broken, so the bark is falling off at a greater pace.

Generally speaking, this is not a problem for the tree -- it is mainly a problem for the tree's owner who has to rake up all the fallen bark!