Friday, February 8, 2008

Deep Freeze Please!

While we're on the subject of the Minnesota deep freeze, here's some food for thought. I know most people dread the cold snaps that are an inevitable element of winter in these parts, but as reported in the Minnesota Monitor, they actually play a pretty important role in keeping some invasive species under control.

Lee Frelich is a research associate at the U of M and director of the Center for Hardwood Ecology. (As a side note, I had the privilege of hearing Lee speak several times during my days as a grad student in the U of M's Natural Resources Science and Management program, and his research on disturbance from fire and storms, and the threats posed to our forests by white-tailed deer and earthworms is mind-blowing, fascinating, and sometimes frightening!) Lee says that extreme cold kills off some invasive bugs, like the European elm bark beetle, which transmits Dutch elm disease. Minnesota used to be able to count on its extreme cold to kill the pests off annually, but as our climate warms, more and more are making it through the winter. Lee says that you have to hope for 25 or 30 below to really do a number on them, and that the colder it is and longer it lasts the better job it will do.

Other bad bugs have been kept out of Minnesota because of cold temperatures here or elsewhere that prevent them from migrating. But global warming may take away this natural defense system, making our native ecosystems vulnerable to several new invaders. The shorter and less frequent these cold snaps are, the more likely it is that we will be adding species to our "Least Wanted" list.

I don't know about you, but that gives me an appreciation for the great Minnesota deep freeze, and even... dare I say it? makes me want it to get colder!

Photo courtesy of Tim Boyle

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