Fence line ecology

Yesterday our crew spent the whole day at Black Earth Rettenmund Prairie basal barking brush: sumac, grape, raspberries (mostly black), honeysuckle, buckthorn, gray dogwood. The weather was surprisingly fine and we made great progress.

Part of the time we were working along a barbed wire fence line that reflected a long history of benign neglect. The photo below is cropped from a 1955 air photo, and shows the fence line clearly.

The neighbor's pasture is to the left and the prairie is to the right. The invasion of woody vegetation is clearly seen. By the time the Nature Conservancy acquired this property, in 1986, the woody vegetation along the fence had become very dense. The first thing TNC did was to organize work parties to clear the fence line and other woody vegetation.

As I described in an earlier post, the land "remembers" and most of the invasive shrubs that we deal with at Black Earth Rettenmund Prairie are concentrated in the former woody areas visible in the old air photos. This includes the fence lines.

So yesterday a lot of our work was along the fence line shown in that 1955 air photo and in the photo to the left. Lots of brambles, grape, and sumac, among other species.

Basal bark treatment (with Garlon 4 in bark oil) is ideal for this sort of area, especially with the relatively small-sized shrubs that we are now dealing with. The other technique, cut and treat, is difficult to do cleanly along fence lines. With basal bark, all you do is treat each individual stem and go on to the next. The herbicide is translocated downward, where any dormant buds and the roots are killed. The stems will all burn up in the prescribed burn we will be carrying out next spring. The only invasive shrubs we should see by summer will be those derived from the dormant seed bank. Eventually, this seed bank will be exhausted.

The basal bark technique is ideal for this time of year, since all the native vegetation has senesced and will be unaffected by any herbicide that might fall on it. With a good spray bottle, it is possible to confine the herbicide just to the lower part of the stem, as the photo here shows. (The red dye delineates the sprayed area clearly.)

Although we still have some problem shrub areas left, we are making great progress. A few more years and then...?