Predicting UW's Hottest Attraction Using Cherry Blossom Models
By Brianna Bonds, ESRM ‘25
People in the Quad out in the cherry blossoms (Image credit: Brianna Bonds).
When I was younger, I had two cherry trees at my house and would spend hours outdoors climbing and admiring them. Unfortunately, they are no more, but my love for them lives on through the ones on the University of Washington (UW) campus. Like my personal connection, UW also has cultural and historical ties to cherry trees. They were originally a gift from Tokyo’s mayor Yukio Ozaki in 1912. A new shipment of trees arrived after the first batch were infested. Some were first stationed at the Arboretum in 1939 and were moved to the Quad in the mid sixties.
Each spring, when the cherry trees in the Quad bloom around mid-to-late March, people from around the world come to enjoy the sights they offer. Since the cherry trees bring beauty, peace, and joy to those who see them, visitors travel far and wide to see these beautiful trees. Often many have to schedule their visit to the city in advance. Timing it right can be challenging, especially when peak bloom only lasts for a few weeks. With global warming impacting when flowers bloom, tourists worry that they might miss them. They don’t want to come all this way for nothing.
A closeup of the cherry blossoms blooming (Image credit: Brianna Bonds).
Luckily, scientists at UW are currently building a model to predict when the cherry trees are in full bloom. Started in 2017, Professor Soo-Hyung Kim and graduate student Michael Bradshaw lead a team of students who take photos of the trees throughout the blooming process and upload them to an app. These pictures are then used to identify which stage of blooming the trees are in.
Researchers are watching for temperature. In order to bloom, trees need a certain number of warm days. They track this using “degree days,” which are measured by comparing the mean temperature of a single day to a fixed temperature number. That output slowly accumulates and builds up over time. This accumulation is also known as growing degree days. When the number of growing degree days reaches a certain threshold, the tree can begin a new stage of growth. By tracking these degree days, scientists can better estimate when the trees will bloom.
A cherry tree branch near Savery Hall (Image credit: Brianna Bonds).
This model produces valuable information for monitoring future climate impacts on tree growth and development. By recording bloom timeline and progress, researchers are assembling a valuable baseline dataset to recognize anomalies in bloom timing and duration under variable future climate scenarios. This model also helps ensure that tourists don’t have to worry about missing out on peak bloom. They will be able to excitedly plan their trips with a higher level of confidence that their traveling efforts will pay off.
A cherry tree in full bloom (Image credit: Brianna Bonds).