(Radio Iowa) – Researchers at Iowa State University using satellite data have found an impact from city lights on trees and plants. Yuyu Zhou, says the impact is significant. “The artificial nighttime lights can advance the start of the (growing) season of the trees, and also delay the end of the, of the trees or plants,” he says. They concluded the lights advanced the date of breaking leaf buds in the spring by nearly nine days and delayed the coloring of leaves by about six days in the fall. He says it’s the first large-scale look at the impact. Those who suffer from allergies could be feeling the impact on the growing season for what it produces.

“Early pollen season and also longer pollen season,” he says. Zhou says the urban heat island effect — where urban areas heat up faster than rural areas also contributes to the growing season changes. He says the change in the growing season can mismatch different trees and mess with the natural cycle. “It will cause the problem of the pollination service. And also another issue is because of the early start up — it can have high vulnerability to the spring frost damage.” Zhou explains.

Zhou is an associate professor of geological and atmospheric sciences at Iowa State. He says there is a positive to extending the season for some plants. “Because we can have a longer growing season in an urban area for an urban farm,” he says. The study compared seasonal changes in plants at around three thousand urban sites.