Good Oak News

Friday, January 11, 2013

Brush Clearing, Before and After

     I love to look at the dramatic difference in a habitat before and after we've cleared brush. This site on Rocky Dell Road in Middleton is an overgrown hill prairie which we are restoring to a savanna condition.

     This site is unique in that it sits right at the very edge of where the glacier stopped its advanced about 21,000 years ago and started melting back towards the arctic. On this site we see both limestone bedrock and glacial erratics, stones carried here by the glacier. On the right side of the "after" image you can see two granite stones that were dragged here by the glacier from the Canada. Also in the "after" image, dead center, you can barely make out a large rock-outcropping in the distance. This beautiful hunk of limestone bedrock, about 6' tall, was completely obscured from all directions by the brush!

Click on the photos for a full-sized image!
     The difference you see between these photos is 2 days of work for a crew of 4. We are completely removing all of the exotic invasive buckthorn and honeysuckle as well as aggressive natives like sumac, prickly ash and raspberries. The biggest problem on this site are the eastern red cedars, which, though native, is well known to invade unmaintained hill prairies. A few scattered red cedars probably lived in places like that bedrock outcropping where fire couldn't get to them (there is one living right on top of the outcropping now). However, over the past 50-150 years, in the absence of fire and grazing they are able to spread rapidly across the hill prairie. All of the cedars we have cut down so far have been less than 40 years old, which makes me think that the last time this area was grazed was in the early 1970's. Or perhaps the old farmers maintained the area with spring burns up until this time to encourage a rapid green-up in the spring for grazing fodder. We are clearing about 95% of the red cedar on this site, but leaving a few for aesthetic reasons at the request of the current land owners.

     Note also that many of the trees you see are girdled but left standing. This saves time, effort and money and also provides habitat for wildlife including a variety of insects, red-headed woodpeckers, bluebirds and other cavity nesters. We girdled or cut down all of the elm, walnut and black cherry in this area. Even though these are native species with value for wildlife, they are not a 'natural' part of this habitat type. Furthermore, we actually cut and girdled about 50% of the northern pin oak, bur oak and shagbark hickories! In most places on the landscape there are no young oaks at all. Here, there were too many, a special place indeed! By clearing some of the oaks we not only increase the light reaching the prairie plants on the ground layer, we also give the remaining oaks more growing space so they can grow faster and be healthier. We may clear more trees in the future as the restoration of this area progresses, but I always think its best to be cautious in our approach to tree thinning.

     There are many diamonds in the rough out there in the landscape like this, ready to be restored. In particular you can see a number of hill prairie remnants along the bluffs in the Black Earth Creek Watershed where this site is located. We must act soon to restore these small fragments of our prairie heritage before the prairie flora and fauna are completely lost under the shade of dense brush. Tom and Kathy Brock have had tremendous success at this at Pleasant Valley Conservancy, and so can you! Don't have your own bluff to work on? Join The Prairie Enthusiasts for their workdays, sites like Mazomainie Bluff can use all the volunteer help they can get!

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