When excess heat kills foliage colors

Our last summer in Utah has been marked by constant heat, no rain and that trend has continued into fall season. As a result our “Kodachrome” foliage season has been a total bust. 

With so much heat and an evident lack of moisture most of our aspen leaves that turn gold right now had their stems so dry that they fell in huge quantities during a severe windstorm the state experienced on September 8.

The result is that most of the trees were defoliated before their colors could even change. Normally, vibrant foliage colors include warm days and cool nights; this stimulates the production of a chemical called anthocyanin, which adds the red in our mountain maples. 

At the same time, the significant difference in temperature between night and day speeds up the loss of chlorophyll from leaves, leaving behind secondary photosynthetic pigments that give us the yellow and orange colors in our aspen groves. 

However, with this summer’s drought and severe heat, the trees were so stressed that many “browned” or loss their leaves prematurely. Usually, the Park City region often see a tourism boost as travelers seek out the vivid leaves of aspen, maples and scrub oak trees, but we experienced our hottest August on record this year. 

Sure the reasons behind fall foliage colors are both complex and not entirely understood, but drought can be a huge factor that will affect its visual quality. Let’s hope this year will be an exception!