Why Are Austin's Trees Having Such A Colorful Autumn?
Austin is known for a lot of things, but fall foliage is not one of them. That is, until this year.
Local trees are putting on an incredible color show lately. It seems like it came out of nowhere, but it didn’t.
“This is my 24th fall in Austin, and I've never seen the tree color as varied and vibrant as it is this year,” Doug Addison wrote to KUT's ATXplained project, asking: "Why? Or is it my imagination?"
It's not your imagination, Doug.
It turns out there are three ingredients that went into making 2018 the best fall foliage year in recent memory: water, cold, and tree diversity.
In September and October, Austin got almost 16 inches of rain. That’s well above average, according to April Rose, the Urban Forest Health Coordinator for the City of Austin.
“Our trees were very well-nourished with water,” she said. “That definitely helped them retain their leaves well into the fall, when some of their leaves may already have been dropping.”
Without getting too deep into the science, more leaves stayed on trees to see shorter days and cooler temperatures. Those are two things that trigger those brilliant fall colors.
Our cooler-than-average September and October helped, too.
“It’s been cooler for a long duration without a really heavy frost,” says Rose. “So it’s given the trees a chance for the [green] pigment to really break down and allow the other, subtler pigments that we don’t normally see to shine through.”
But different leaves react differently to the cold. That’s where our final ingredient — tree diversity — comes in.
Over the years, Austin’s urban tree canopy has become much more varied in the different types of trees it contains. Part of that is intentional — the city plants different kinds of trees to prevent species-specific diseases from doing too much damage.
But, it also means good fall foliage conditions bring lots of different colors than Austinites normally see.
“It just seems like all over town, all the trees are getting in on the act,” says our question-asker Doug Addison.
“I look at trees all day every day and I am also overwhelmed this year by the brilliance and diversity of colors,” says April Rose. “It’s very spectacular this year.”