Why do some trees hold onto their leaves in the Fall?

We all know that the Acadian Forest has some of the most beautiful colors in Fall, but have you ever wondered why some trees hold onto their leaves, when others drop them right away?

Most broad leaf (deciduous) trees begin to lose their leaves as cold weather approaches in the Fall and Winter Months as a strategy to minimize the damage associated with colder temperatures, and to retain water. Other trees, such as beech red oak and Ironwood can hold onto their dead leaves during the Fall and Winter, and some may hold them until the Spring unless they are blown off by strong winter winds! This is due to something called “Marcescence”.

Marcescence is a phenomenon that causes a tree to retain its dead leaves well into winter months, and even until the spring when new leaves develop! Trees usually exhibit marcescence when they are young, but it can also persist in older trees, especially on their younger branches.

Many believe that trees do this as a defence mechanism, to deter wildlife from browsing on the tree buds during the winter. Others believe it could have something to do with nutrient cycling- by dropping their leaves later in the Spring, the leaf decomposition at this time may provide increased nutrients/moisture to the tree. Most likely it is combination of many factors!

Like many things in the forest, the true reason behind retaining dead leaves may still be a mystery, but recognizing which trees do this may help you with your winter tree identification!