Crow’s Nest: Restoration of a suburban lot

June 5, 2012

It’s a commonly held belief that once land is developed into houses, streets, stores and parking lots, it will never be natural open space again. Overwhelmingly, this is true. At least in the time that we humans will be on the planet, it is unlikely that much of the built landscape will return to anything that is functionally natural. Everyone needs a place to live and it’s challenging enough to save and steward open space, much less to create it out of developed land.

Occasionally, however, there is the rare opportunity to do some ecological restoration on a previously developed lot. Crow’s Nest added a small but significant lot to the preserve last fall. It is in the center of the preserve and located at an intersection that serves as the gateway to the preserve near our 19th century barn/visitor center and gravel parking lot. It had a small house on it, perched right on French Creek. The septic system was failing and the water table was high enough that storms flooded the basement. It proved much less expensive to take the house down than to replace the failing systems. I miss the wonderful neighbors who were renting the house, but the restoration of a turfgrass lot back to woods is providing a unique opportunity and will benefit stream quality and wildlife habitat while maintaining the intersection’s sight lines. The project has the potential to turn a small corner of the preserve into a showcase entryway.

Taking the house down was by far the most noticeable change on the site, but is only one item on a checklist of projects that will make the site a more natural woods edge instead of lawn. Some trees and shrubs I planted last fall along French Creek prior to the start of the project, to serve as a buffer for French Creek. I also spent some time last year controlling garlic mustard along the creek there, which made this spring’s efforts a bit lighter.

Removing the house and macadam driveway substantially reduces the impervious surface and slows runoff, allowing more of the rain that falls on the land to sink into the ground instead of racing into the stream.

There were also three Norway maples in the yard. They seed prolifically and will interfere with our ability to return the land to native woods. I’ve taken one down; two to go.

I rerouted a small trail that leads from the visitor center through to the new property; at the end of the project we hope to build a small footbridge where the trail crosses a drainage ditch that runs through the woods there.

At our volunteer cleanup this spring volunteers planted the first row of shrubs that buffer this drainage ditch; instead of having lawn right up to it there will be shrubs and wildflowers along the bank. Volunteers also removed a truckload of trash and another of the invasive biennial, garlic mustard.

The existing yard had been based in part on imported fill to raise it up above the floodplain (back when that was an acceptable practice). Now when you dig to plant trees you come across various artifacts and trash.

All of the shrubs we planted so far are surrounded by drip hoses since we were in the midst of a drought when they were planted (the wildfire was burning in French Creek State Park that week).

Most of the house footprint I planted with turfgrass seed to stabilize the soil, though part of it received wood chips instead. For the part of the existing lawn that I’m converting to woods edge I sprayed the grass to kill it and then spread 30 cubic yards of uncomposted wood chips over the ground. Eventually this will more closely approximate the conditions on a natural forest floor and encourage the fungi upon which tree roots depend.

I think I will re-do this curve of mulch and grass so the mulched (future woods) sweeps out more into the area that is now turfgrass (see photo above): less lawn and a more aesthetic curve. The foreground in the photo is the former driveway that will eventually also become a strip of turf along the road.

Of course there are always unforeseen complications. The topsoil brought in to fill the house location had weed seed of Japanese hops (Humulis japonicus) in it that promptly germinated along with the grass. We don’t have this weed elsewhere on the preserve, though it can be found on farms in this county, and I didn’t want it to spread. I sprayed that with a broad leaf herbicide to kill it without killing the grass.

I’ve had the power and phone lines removed that ran to the house; I’m still working on getting a wire that is rubbing an existing canopy tree moved a foot or two to spare that tree (it looks like an easy solution, otherwise I wouldn’t ask).  I also have added the mowing of the remaining grass to my weekly routine (an extra 10 or 15 minutes).

The tree planting will probably wait until the fall when these other tasks are completed. I am basing my design in part on a just-completed research paper by Sara Street, a student at the School of Environmental Design at Temple University. She did some of her research here at Crow’s Nest and has shared some her design proposals to “seal the edge” of the woods to prevent wind, light, and weed seeds from degrading the woods edge and negatively impacting the large canopy trees. New canopy trees will not be planted to the edge of the designated woods zone. Instead, following a diagram by Restoration Ecologist John Munro (one of Sara’s instructors; I also took a class with him in 1996), the transition area will gradually descend in height with smaller trees, shrubs, and wildflowers so that the edge becomes an “aerodynamic” shape in profile.

Next year we will likely install some directional signage on the corner to lead visitors to the preserve. Keep an eye on this site when you visit to see if I am successful at restoring a natural-looking and functioning woods edge there.

Posted by Daniel Barringer on June 5, 2012.