Appreciation: First International Cherry Blossom Prediction Competition

wcutler · Mar 19, 2022

The First International Cherry Blossom Prediction Competition ended on February 28, 2022. Students, researchers, and citizen scientists competed to predict the peak bloom date of cherry trees at four locations around the world: Washington D.C., USA; Kyoto, Japan; Vancouver, Canada; and Liestal-Weideli, Switzerland. Vancouver selected for its location the 'Akebono' trees in Maple Grove Park, at the corner of SW Marine Drive and Yew Street. Douglas Justice, Associate Director, Horticulture & Collections at UBC Botanical Garden, agreed to determine the blooming date for these trees and has been photographing them beginning on March 10. With hardly an data to go on for our location, the contestants came up with April 2 as the peak bloom date (70% open) this year for our location's trees.

I will collect the set of photos here. You can see photos of the trees in bloom in previous years in the Kerrisdale | UBC Botanical Garden Forums thread. Photos from last year are in posting #167 in that thread.

So far (until March 18) there has been barely any discernable colour. Here is the first photo, taken March 10.

These are in date order, March 15 to 18.

In warmer areas of Vancouver, this cultivar is much more advanced, flowers lightened up and puffy, some flowers already open. But temperatures are supposed to reach and stay at 15C degrees next week, so that should advance the flowering here in Kerrisdale quite a bit.

wcutler · Mar 22, 2022

Douglas has added blossom photos to the set, so here are
March 21

March 22

wcutler · Mar 25, 2022

Douglas's photos from March 23

March 24

wcutler · Mar 25, 2022

I swung by the park last evening, March 24. I'm glad I'm not calling the peak bloom date on this. The tree to the right is ahead of the others, at least on the branch closest to the road.

wcutler · Jan 11, 2023

Here are Douglas's photos from March 25, In the third photo, you can see the branch where I photographed the flowers above, at the right side over the black car - clearly ahead of the other blossoms.

wcutler · Mar 29, 2022

Open! How did this happen in three days?!

wcutler · Mar 31, 2022

Stephen Quinn of CBC Radio Early Edituin talked on March 30, 2022 with elizabeth-m-wolkovich who is with the Biodiversity Research Centre in the UBC Department of Forestry. She is one of the people who launched the competition, The 7-minute podcast is at
https://www.cbc.ca/listen/live-radi...ion-help-predict-future-cherry-blossom-blooms.

wcutler · Mar 31, 2022

I don't know if this link will work for people, a Vancouver Sun article interviewing Douglas Justice:
Project open to all aims to predict cherry blossoms

UBC asks global citizen scientists to predict cherry blossom seasons - Vancouver Sun (2022-03-31)
They let me copy this. Am I allowed to post it?

Project open to all aims to predict cherry blossoms

Vancouver Sun

31 Mar 2022

GORDON MCINTYRE gordmcintyre@postmedia.com twitter.com/gordmcintyre

Here's a wonderful idea: Plan a wedding for when cherry blossoms are in full bloom.

Except, and this is the tricky part, there are so many factors that determine when (and where) blossoms first open that predicting “peak bloom” is like picking ahead of time a day it won't rain.

“It's not as predictable as you might think,” said Douglas Justice, associate director of horticulture and collections at UBC Botanical Garden.

To help predictions in the future, one of Justice's colleagues, climate change biologist Elizabeth Wolkovich from UBC's faculty of forestry, began the first international cherry blossom prediction competition, which ended Feb. 28, asking students, researchers and citizen scientists in Washington, D.C., Kyoto, Liestal-Weideli (Switzerland), and Vancouver to predict the peak bloom date this year at four specific locations in each locale.

In Vancouver, that's Maple Grove Park near the Marine Drive Golf Course, which Justice has driven by every day to photograph the trees.

By combining non-expert predictions from the competition with the research already known, scientists hope to compare approaches to better find ways to forecast peak blooms.

Peak blossom dates are complicated to predict because, for one, the weather is not the same year by year.

And even in Vancouver, cherry trees will be at peak blossom at different times in the West End and, say, Riley Park-Little Mountain because of small differences in microclimates.

Cherry trees need a certain number of hours (in the high hundreds) of -7 C or lower temperatures while dormant for the winter before they begin their spring growth, the better to make sure they don't get hit by a late frost.

“That would be straightforward and you could measure that knowing how much cold weather a plant has experienced, but unfortunately it's not that simple because there's also a heat requirement,” Justice said.

For the buds to expand and then draw water and nutrients up from the roots, the weather needs to be warm enough for the tree to do so.

“The warmer it is, once the chilling requirement is met, the faster the plants will come into bloom.”

This winter was a good example, Justice said.

The chilling requirement was easily met with cold spells in December and February, but March was slow to warm up and folks from scientists to Vancouver Cherry Blossom Festival organizers to home horticulturists figured the blooms would be relatively late this season.

“Then, all of a sudden, we got some pretty good temperatures in March and things started to happen very quickly,” Justice said.

On March 25, for instance, fewer than 10 per cent of blossoms on the Akebono cherry trees at Maple Grove park were in bloom, but by Sunday that figure was approaching 80 per cent.

“We could see the buds fattening up and all of a sudden, `Kaboom!'” Justice said.

Japan has been keeping records of cherry trees for a millennium, but the records for the ones in the Kyoto control group go back 150 years. Vancouver's cherry trees go back less than a century, and Justice has been studying them for at least four decades.

“I know the history of cherry trees in Vancouver from at least the last 40 years, and we're probably on average a week earlier than I recall when I first started looking at cherry trees,” he said.

The point of the competition is to spark more discussion about climate change, and one thing scientists do know for sure is cherry blossom season, on average, has begun earlier and earlier in the spring over the past four decades.

“It would be really good to have a kind of predictive model that's accurate for the Cherry Blossom Festival, for example,” Justice said. “At the same time, I kind of like the fact that it's nature that is determining these things, and maybe it's nice to be surprised every once in a while.

“But underlying all that, of course, is that we're seeing a change.

“A week over four decades, that's a helluva lot. Does that mean it's going to be two weeks earlier in another 20 years? I don't know. Clearly, we have to monitor these things.”

Click to expand...

wcutler · Jan 11, 2023

And thanks to @Georgia Strait for posting this link elsewhere on the forums.
Citizen scientists predict cherry blossom peak (ubc.ca)

wcutler · Jan 22, 2023

Here is the thread for the 2023 contest:
Appreciation: - Second International Cherry Blossom Prediction Competition - 2023 | UBC Botanical Garden Forums

The competition's website has links to last year's entries, where you can read how various entrants went about coming up with their blooming date predictions.
Cherry Blossom Prediction Competition – Cherry Blossom Peak Bloom competition (gmu.edu)

I don't know that I should close this thread, but please, do not post anything here regarding the current contest.

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