By Adam Gundlach and Bryn Scriver, Lakeshore Nature Preserve
Large, old, open-grown oaks (oaks with large outstretching lower limbs) are disappearing from the landscape of southern Wisconsin. These trees are remnants of the ecosystem that used to dominate the area—oak savanna. Very little of the original oak savanna remains in the state today (only one-tenth of 1 percent remains). They were lost to agriculture when the area was settled by immigrants. Centuries old oaks were swallowed up by quick growing tree species. This successional process is on display in the Preserve’s Frautschi Point Woods. Young oaks cannot get established in the dense shade of these trees and the invasive woody plants that came in after.
The single large oak tree circled in yellow in the 1927 air photo is indiscernible from the surrounding trees in the 1968 air photo. Note the recently constructed 700s and 800s apartments in the 1968 photo.
Oaks are a keystone species — a species that serves as the backbone of an ecosystem. Oaks support more life forms than any other native trees. They host hundreds of species of insects, supplying many birds and other wildlife with an important food source. Climate-change models show that the future climate of Wisconsin may be more conducive to oak woodlands in the future, so it makes sense to work to save what we have. If we want to have oak-dominated woodlands and oak savanna again, then we need to promote their establishment by increasing light levels to the ground layer where their acorns wait for the chance to grow into a tree (if not eaten first).
There are few precious places where we have younger oak in the Lakeshore Nature Preserve. One of those places is just east of the 800s apartments around what we call the “Second Oak” on Big Oak trail near the Biocore Prairie field edge. In 2006, volunteers cleared woody brush from around the 150-200 years old tree to give it some space and light. The clearing may have come a little too late; since then half the tree has fallen, but the younger oaks remain. To give them a chance to grow into the next large canopy trees and allow them to reproduce naturally we are undertaking a project this winter to remove select competing trees growing into the canopies of these oaks. Some competing trees will be felled and removed from the site, while others will be girdled (the bark taken off in a strip around the tree) and left as standing snags. As conditions allow, seed will be sown and prescribed burn plans drafted for the southern edge of Frautschi Point to aid in maintaining an open community around the oaks.
As neighbors and visitors to the Lakeshore Nature Preserve, you may notice some of this work. We hope you will be as excited as we are to see the conditions improve for the health and longevity of these special trees.