A Visit to Big Grove

Yesterday morning I skipped the Greenway and instead went to Big Grove Preserve for an informative hike, guided by property steward Ken Lowder. Big Grove is a Bur Oak Land Trust property just a few minutes' drive from Iowa City (Bur Oak owns and maintains 11 properties in and around Johnson County, which are open to the public). It takes a couple of gravel roads to get there, and some poorly-placed "Private Property" signs erected by neighboring property owners may make you think you are on the wrong track (neither the access road nor the preserve are "Private Property" so don't be discouraged if you are trying to visit), but it is worth the trip.

Big Grove consists of a 40-acre parcel of original land along with a newer acquisition of another 40 acres. There is a small patch of prairie flowers near the entry, swarming with butterflies and other pollinators, but most of the land is shady woods. The plant life is much different from that of the sunny Greenway, with tall oaks and hickory towering over white clusters of snakeroot, zigzag goldenrod and occasional blue lobelia. An ephemeral creek runs amid rocky, moss-draped outcroppings.

It is a quiet getaway; visitors can expect silence punctuated by calls of resident pileated woodpeckers, or warbler song as they migrate through. As we walked, Ken told us about some of the history of the land and the work that goes into restoring and maintaining forest.

  When Bur Oak acquired the original 40 acres in 2003, it was overrun with non-natives like garlic mustard, honeysuckle, autumn olive, and multiflora rose--all of which grow thick in the understory and choke out desirable native plants. The property stewards, with help from regular volunteer groups, worked tirelessly to cut back the invaders, giving other species room to grow. The difference between a piece of forest that has been maintained and one that has been left "wild" is night and day: a scrubby, prickly, and impassible area transforms to an open wood that you could drive a cart through (as the woods were described by early settlers). The trees naturally have few lower branches, since they don't receive enough sunlight below the canopy to make them worth the effort to maintain.

Unmaintained woods

Woods after cutting back invasives and burning

As you walk through the woods, you will encounter many tall trees that are girdled, with circular cuts all around their base. These are specimens that have been condemned to die so that the forest may live: for the native oak and hickory populations to thrive, their saplings require sunlight. By selectively killing (but not removing--their corpses provide valuable habitat for cavity-nesting birds) less-desirable trees, the canopy is opened up to allow more sun to reach the forest floor so those saplings can grow.

Early stages of what will be oak savanna.

After a short climb in the newly-acquired parcel, Ken showed us an open section of land that had been used (and was still being used) as pasture, which Bur Oak is planning to restore to an oak savanna. Oak savannas are scenic transition areas between woods and prairie, with grasses and forbs growing in the open sun punctuated by occasional bur oak trees. These savanna trees grow differently from their forest brethren; because they are not competing shoulder-to-shoulder with other trees for sun, they are able to spread their limbs and maintain strong, sturdy low branches. These oaks can survive hot prairie fires that kill competing trees, creating a unique habitat--and a lovely vista.

Although it is wonderful to see land being conserved by Bur Oak Land Trust and other trusts around our state, it is overwhelming how much work goes into simply maintaining them in their "natural state." Because of the invasion of aggressive non-native plants, we can't just leave areas "wild" and expect them to stay "wild." We must treat them instead as huge gardens, constantly weeding out the undesirable and planting and preserving the desirable. And that takes a lot of work--most of it done by hardy volunteers like Ken Lowder and the many other individuals and groups who give their time and sweat to preserve a little bit of our natural heritage.