Speaking of looking the same-- you may have noticed the area on the left has far more trees than the rest of the prairie. Why is that?
This is actually a similar, but distinct, ecosystem called “oak savanna.”
Oak savanna is defined by broad, spreading trees, and an understory adapted to sun and dappled shade. Think of it as a cross between a woodland and prairie.
True to its namesake, the most common trees are oaks, with the most iconic being gnarled burr oaks.
These trees grow in the open, with space in between them so they get light from all sides. You’ll notice the branches spread out, sometimes all the way down to the ground.
The widely spaced oak trees can create areas of open sun, dappled shade, and dense shade. The mixture of shade and sun creates a diverse habitat that can sustain more plant and animal species than either a woodland or prairie alone. Plants that thrive in prairie and dense woodlands can survive here.
Additionally, plants that favor patchy sunlight grow beneath the spreading branches of the oak trees. Leather flower, purple milkweed and Pennsylvania sedge are a few examples of plants that prefer oak savannas.
The wildlife inhabiting the savanna are those that use both trees and grassland. Look for red-headed woodpecker, eastern bluebird, turkey, and white-tailed deer. Endangered Indiana bats can also roost under the peeling bark of dead trees.
You’ll notice some parts of the savanna are dense with trees. The absence of fire for much of the past 200 years allowed native trees that normally live in wet areas to invade the savanna. The thick growth of cherries, elms, buckeyes, hackberries, and walnut trees drastically changed this ecosystem.
Seedlings of these trees can grow in shade, but cannot survive fire. However, once they grow to a large size, they can resist fire and must be cut down or killed to help restore the oak savanna. On the contrary, slow growing burr oak seedlings can survive fire, but require sunlight to survive.
Prescribed fire is an important management tool for oak savannas because it promotes the growth of oaks and eliminates competing trees and shrubs.
To better experience this endangered ecosystem, consider taking a walk on the ½ mile gravel-based loop trail.
Or, to continue on to our last stop, take a right out of the parking lot, then a left back onto our paved entry road.