My wife, Sue, and I hiked the trails at Robison Wildlife Acres south of Nevada with some friends last Sunday afternoon. The area has changed alot since I helped build those trails many years ago. The original 58 acres of the 78 acre preserve were donated to Story County in the 1960s by early conservation board member, Clay Robison. The donation included oak-hickory wooded ridges above West Indian Creek and an open pasture area that was being colonized by young oak and other trees. McFarland Park and the Skunk River Greenbelt hadn’t become public land yet. The Robison land hadn’t been grazed for many years and was the county’s best place to see woodland wildflowers.
Not much was done to manage the area for many years other than to build and maintain the trails. Nature never stands still, though, and changes slowly but surely altered the appearance and ecology of the area. Wild flowers still bloomed every spring, but alien invasive plants like Asian Honeysuckle and Multiflora Rose began to proliferate beneath the old open-grown oaks and hickories. So did seedlings of some shade-tolerant native trees like ironwood and basswood. What had been open woodland gradually become so dense that sunlight seldom reached the forest floor. Herbaceous plant cover declined and left bare soil with little to protect it but a scattering of the previous year’s dead leaves. Birds and animals that favored the open woodland habitat disappeared, too.
Several years ago another invasive plant called Garlic Mustard appeared. This aggressive annual plant competed directly with the area’s wildflowers right at ground level. Something had to be done, or risk losing what was still one of the county’s best spring wildflower displays. Hand pulling garbage bags full of garlic mustard each spring held that plant at bay, but it obviously wasn’t enough. A plan slowly emerged to restore Robison Wildlife Acres to something like it was when Clay Robison donated it nearly 50 years ago.
Several years of cutting invading honeysuckle and rose were undertaken by conservation staff and volunteers. It was hard hand labor and progress could be quickly lost with only a year or two’s inattention. A new group called Conservation Corps Iowa (CCI) became available a few years ago, and was contracted to do some major clearing work. CCI crews came with their own equipment and loads of youthful energy as they cleared acres of brush and small trees. Sunlight again filtered down to the ground through the canopies of old open-grown oaks and native plants began to respond. Goats were known to preferentially graze small woody plants like honeysuckle, rose, and tree seedlings. Special electric fencing was acquired and an experimental goat herd was brought in. The fenced enclosure was moved as the goats cleared each area of invading woody growth.
The goat fence was just reinstalled for another year’s goat grazing, and CCI will again be contracted to continue their clearing work. Conservation staff added another missing ingredient in the restoration effort in the past year with the reintroduction of woodland fire. Woodland fires aren’t the raging blazes that prairie fires can be. They tend to be slow, low, and creeping through dead leaves on the forest floor. They set back growth on small woody plants while not hurting larger trees. Well-timed woodland fire can even kill sprouting seedlings of annual Garlic Mustard while not hurting perennial native wildflowers.
The result of ongoing restoration work at Robison is impressive. A carpet of Spring Beauty and Bluebells has spread into recently cleared and burned areas of newly opened woodland. Native sedges are reappearing in areas that had only dense woody growth and bare soil a few years ago. To top it off, bluebirds were seen and heard where it had been far too dense for them for many years. Pressure from Multiflora Rose, Honeysuckle, and Garlic Mustard won’t stop, but ongoing restoration work by Story County Conservation will keep them under control as native plants and wildlife reclaim land that couldn’t support them for years.