CLEVELAND, Ohio – For those who think fall colors came late this year, leaves can be deceiving.
That’s the message from Marty Calabrese, naturalist for the Cleveland Metroparks at the North Chagrin Nature Center, running counter to what a lot of other people have been saying.
By his observation, leaves on the trees in the Metroparks started changing color right on time, and the many native species, including black gum, sugar maple, tulip tree, black walnut, American beech and various oaks hit their collective peak around Oct. 18, only a day or so later than usual.
That may come as a surprise to many leaf watchers, he said, but that could be because they’re looking at trees in their neighborhood that may be non-native species or ornamentals that stay green longer.
To get the most accurate readout on the timing of fall foliage one really needs to be on a trail in a natural setting, he said. Instead, people peer out their window and make assumptions about leaf change because they “love to say late or early.”
However, one thing that does seem to be happening everywhere is that the leaves are sticking to the trees longer than usual, Calabrese said, making fall seem like it’s late when its really lasting longer.
Not an exact science
There are many variables that determine when leaves will change color, and drawing conclusions about peak is not an exact science. In fact, the consensus of several experts contacted by cleveland.com and The Plain Dealer is that the annual turning of the leaves did indeed start later this year, perhaps by as much as week or two.
Robert Edwards, the new assistant curator of environment at the Cleveland Museum of Natural History, said it’s possible trees in the Metroparks started turning ahead of other regions because they are of a species triggered to respond more to changes in day length than to changes in temperature.
When temperatures drop in tune with the shortening of days, that’s when you get the broad, coordinated displays of color, according to Edwards.
On the whole, he said, an unseasonably warm October caused leaves to start turning later this year in much of the East.
And it certainly was warmer than usual in Cleveland. The coldest day in October was the 24th when the temperature dropped to 37 degrees. Cuyahoga County usually experiences its first freeze in the last week to 10 days of the month, said Brian Mitchell, a meteorologist with the National Weather Service in Cleveland. It did not happen this fall until Nov. 4.
Tyler Stevenson, urban forestry program manager with the Division of Forestry, said by his observation, leaf change began a week or two later this year. He said that appeared to be the case in central Ohio, where he works, but also likely around the state, although there are micro-climatic conditions that could provide for exceptions.
At Holden Arboretum in Lake County, peak started around Halloween when the nights turned cold, said Caroline Tait, vice president of horticulture and collections at Holden Forests & Gardens.
It seemed to her, she said, that there was a sudden leaf drop in early fall from some trees, followed by a long period of warm days and nights before trees were sparked into action.
Bye-bye chlorophyll
Leaves start to change color as their chlorophyll starts to break down, exposing other pigments in the leaves, such as carotenoids, which create orange hues, and xanthophylls, which produce yellows.
When conditions are right, the leaves of some trees start producing anthocyanins, which turn leaves red or in some cases purple.
But not everything has an explanation.
Usually at this time, oak leaves go straight from green to brown, Calabrese said, “but for some reason, the northern red oaks are taking their time and dancing in that yellow stage.”
He doesn’t know why.
Variations are not unusual, he said, because each tree may have its own set of stresses that affect leaf change that the same kind of tree one block over may not.
Hanging on longer
Also interesting about the fall foliage this year is that leaves have been staying on the trees longer. That’s partly because there have been no vicious storms to rip the leaves from their branches, Calabrese said.
The average wind speed for October was 8.3 mph, topping out at 28 mph on Oct. 21 and Oct. 31, said Brian Mitchell, meteorologist with the National Weather Service in Cleveland.
Also, adequate rainfall meant less stress on the tree, prompting it to hold on to its leaves longer. Precipitation in September was below normal but in October it was 1.29 inches above normal, at 4.89 inches for the month.
“It was a perfect fall foliage formula,” Calabrese said.
One thing that Calabrese noticed this year is that the east side of the Cleveland area started seeing leaf change three to five days before west side, based on text messages exchanged between himself and several other naturalists.
Again, he doesn’t know why.
Climate change at work
While many localized variables contribute to leaf change, so does one giant all-encompassing factor, and that’s climate change.
Edwards said a general warming trend and increased rainfall are both the result of climate change, and those weather conditions impact fall foliage.
Plants that get adequate water are less stressed out and not as quick to drop their leaves, he said. Also, moisture in the soil helps keep it warm, which encourages trees to hold on to their leaves.
“Extreme weather is what’s happening which means we’re getting extremes in terms of timing of things as well,” Edwards said.
Said Tait, while it’s difficult to predict peak color because of all the local variables, climate change and the warming that comes with it threatens to continue pushing back its arrival in the years to come.
At Holden Arboretum, she said, peak leaf color now tends to occur at least a week later than it did 20 years ago.
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