Tuesday, March 14, 2017

Early spring followed by late frosts

Posted by Richard B. Primack

“To us snow and cold seem a mere delaying of spring. How far we are from understanding the value of these things in the economy of Nature.” 
-Thoreau, March 8, 1859, in his Journal

As a result of climate change, unusually warm days in February and March often trigger early spring activity by plants and animals. This year, many introduced wildflowers, such as crocuses, winter aconite, and snowdrops, were already flowering in late February, stimulated by three days of record high temperatures in the high 60 and low 70s. In the woods, skunk cabbages were flowering, woodpeckers were drumming their territorial call, and turkeys were forming courting groups.

Snowdrops were in full flower on February 27 this year:

But this early biological activity in late winter exposes animals and plants to dangers of extreme cold conditions. And this week, winter returned with a vengeance with temperatures below 10 degrees F and an inch of snow. With this kind of variation in winter temperatures, we ask: Will hard frosts on many successive days damage the early flowers and swelling leaf buds? Will there be a penalty to pay for the early plants?

This year, I wondered if these early crocus flowers would be damaged by the freezing temperatures:

And after several nights of hard frost, the crocus flowers are indeed all frozen and wilted. It seems they paid a heavy price for flowering early:

For more details, check out Seth Borenstein's story in Associated Press.

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