ITHACA, N.Y. – All signs point to a great season for colorful leaves this fall in Tompkins County forests, according to Cornell Botanic Gardens lead arborist Lee Dean. In the City of Ithaca, though, the foliage season’s timing and intensity are anyone’s guess.
Urban foliage is unpredictable because of human impacts. First, we’ve brought a diverse bunch of trees to Ithaca. Native species and specialty cultivars grow side by side along the city’s streets. Outside our office window, a Sargent Cherry (native to Japan and Korea) stands next to a Horsechestnut (native to the mountains of Greece and Albania) and across from a Honey Locust ‘Streetkeeper’ (a variety of a North American tree cultivated to have a tight, columnar shape).
The City of Ithaca keeps a tree inventory, overseen by the Parks and Forestry Division of the Department of Public Works. The 2018 inventory, which we used to make the map below, includes more than 400 unique varieties of trees within city limits.
A statewide foliage map shows leaves just starting to turn in the Finger Lakes region and already peaking at the start of October in the Adirondacks. Within each area of New York though, color change varies significantly between forest and city, mountain and valley, and even tree to tree, according to Dean.
Native varieties generally change more dramatically than non-native varieties, Dean said. Red maples that are indigenous to New York, for instance, may turn red sooner, and perhaps more brilliantly, than non-native maples.
Across tree varieties, caretaking impacts urban color change. To achieve maximum brilliance, trees need adequate water. Even in a rainy year, urban roots might not get the water they need if it runs off impermeable surfaces. Dean said forest trees regulate their moisture effectively, “but when we bring the trees out of the forest we have to do all the mulching and watering.”
In general, healthy trees produce brighter leaves. The forest ecosystem is self-regulating, Dean said, but in the city caretakers have to do extra things to keep trees healthy, like pruning and testing for signs of disease.
Dean is confident the area’s forests will soon feature magnificent reds, purples, oranges and yellows. “It’s a great year for color in the forest. We’ve had moisture, it’s been a great growing year for plants… the forest right now is ready to go for color change. I think it’s gonna be fantastic,” he said.
Those looking to see forest foliage should get out into the woods soon. Check out Ithacatrails.org to find some places to explore.
The city’s trees, though, are a whole different beast. “Tree color around the City of Ithaca is going to depend on how trees have been cared for, because they’re not in a natural environment,” Dean said.
Tree Map: We need your help!
We made a map to track color change within city limits, using the city’s 2018 tree inventory. Right now, the city’s trees are mostly green. We need your help tracking them as they change over the coming weeks. Send your best foliage photos of Ithaca’s street trees to firstname.lastname@example.org. Be sure to note the time and location. We’ll update the map and post a few of our favorite photos each week.
For the week of Oct. 1 – 7, we’re estimating about 10 percent color change.
In the meantime, while the season is unpredictable Dean said there are a few telltale signs that color change is coming.
Watch for cool nighttime temperatures. An extended stretch of nights between 32 and 45 degrees is best for pigmentation. Beware of storms. Harsh wind and rain can knock leaves off trees before they have a chance to change color, limiting the overall magnificence of the season.
Lastly, let’s hope winter doesn’t set in too early. Freezing temperatures can kill leaves before pigments have a chance to turn, resulting in a mostly brown canopy.
Featured image: Van Dorn Road in Ithaca on Oct. 4. (Photo by Kelsey O’Connor/The Ithaca Voice)