Saturday, April 25, 2009
Watching Friday afternoon's prescribed prairie burn in the UW Arboretum's Curtis Prairie
I saw the smoke drifting over Lake Wingra from the Arboretum Friday afternoon, grabbed my camera and jumped in the car. I've never seen them doing one of their spring burns in Curtis Prairie up close. I wasn't going to miss the opportunity.
It was a lot windier than I would have thought appropriate for burning a prairie, but it turns out that what really matters is not so much the wind speed as that it stay steady and consistent in direction -- and that back burns are properly set and big enough to stop the fire when it reaches them. Which was the case. The "firemen" (and women) who both set the fires and kept them under control were Arboretum grounds staff.
This was the back burn along Arboretum Drive that would contain the conflagration after the head fire, which was started upwind along the Beltline, raced across the main part of the prairie. Note how carefully they worked. Right alongside the worker with the torch lighting a new line of fire on the left, there was another with a water hose. The back burn takes most of the time. After that, the head fire just races across the prairie, and it's soon all over but the mopping up.
The Gaylord Nelson Institute for Environmental Studies has a paper about Curtis Prairie, its history and ecology on their website. It was one of the first attempts in the country, under the guidance of Aldo Leopold and others, to restore the native Tallgrass Prairie that had once covered most of the middle of the continent. Periodic fire (started by lightning in nature and now managed by humans) has always been a part of the prairie life cycle. They try to burn each part of the prairie two out of every three years, though weather can shift that schedule. Friday was chosen because the day offered the right combination of humidity, wind speed and direction. It was also probably their last chance of the season, and they decided to go for it.
Note: I'm putting additional photos of the spring burn in this Flickr Set as I get a chance to process them.