Habitat Specialist Andrew Eberly has many roles here, including growing seedlings for our plant sales, conducting plant and bird surveys, and helping to manage our 900-acre property. Here he shares some of the thinking that goes into taking care of our land.
Each fall I find myself out in the fields doing the repetitive, physical work of controlling the trees and shrubs that have worked their way into the 300 acres we are trying to manage as grasslands or shrubby savannas. This is time-consuming and sometimes arduous work, but it’s also enjoyable in many ways. It gives me a close look at what is growing out there and allows me time to ponder the pros and cons of the methods we are using to manage the land. What follows is a sample of some of these thoughts. To start with, there seem to be as many approaches to managing land as there are land managers and that’s OK. We are working with ecological processes that play out over tremendous periods of time and we must be at peace with the fact that a human lifetime isn’t long enough to see the results of all of our plans and hard work.
We’re all about grasslands here at Clifton. They are the most imperiled habitat we have and the plant species that comprise our remaining grasslands won’t survive if trees shade them out. The easiest thing would be to mow them short every year, but transitional habitats are also valuable. It’s a constant struggle to strike a balance between what is feasible from a management perspective and creating a mosaic of multiple successional stages.
The field we call Turkey Gap is an old pasture in the process of diversifying and reverting to a wilder type of shrubby savanna ecosystem. It’s a good example of the kind of transitional habitat that we want to make sure persists. Most of Turkey Gap gets bush hogged regularly, but for the last three years I’ve set aside a small area to see if there’s any chance of maintaining it without mowing. Mowing is a necessary tool in grassland management, but in my experience it has some downsides. For small animals living in fields, mowing is a catastrophic event. Also some invasive woody plants actually increase when they get mowed once a year. Finally, mowing has a tendency to smooth out the natural heterogeneity of sizes and ages naturally found in grasslands and shrublands.
My experiment now hosts hundreds of Tulip Poplars, Black Walnuts, Autumn Olive, and many more tree species that have already reached 15’ to 20’ in height. The result is a beautiful early successional woodland that hosts nesting American Woodcocks, roosting Red Bats, Box Turtles, and countless other animal species that seem to depend on having some scraggly, immature woodland patches within their home ranges. But soon my little section of Turkey Gap will grow up into mature forest unless I do something about it. Removing tree seedlings by hand with loppers and spraying the stumps with herbicide is the most targeted approach. Moving slowly through the habitat in this way allows me to find and avoid killing special native shrubs like Southern Crabapple and American Plum, along with more common species like sumacs and native roses that I believe should have a place in any savanna. Basal bark spraying with herbicide is a quicker strategy I plan on exploring in the future.
Why do I have to use chemicals anyway? Most of our perennial broad-leaved plants are adapted to being broken, burned, or cut periodically and they will happily resprout repeatedly with more individual stems each time. Invasive Autumn Olive is especially good at the “hydra” growth pattern. Herbicide is necessary to prevent the trees I’m removing from growing right back. Ultimately we are trying to mimic the natural disturbances of fire and grazing, so why don’t we just burn it and put some Bison out there? We will! Well, maybe not bison. Bison are a challenge to contain and they eat mostly grass, so they are hard to work with. We do prescribed burns, but they can be logistically hard to pull off. Fires are particularly challenging during the growing season when they would have the biggest impact on tree growth. Plus, in many parts of the Clifton property–even places that get burned repeatedly–woody species sometimes keep growing and eventually dominate to the point where they inhibit the growth of more flammable grasses and wildflowers, which prevents fire from having the effects we want it to. Some spots simply don’t want to burn.
It seems that if we want grasslands and savannas alongside forests on a medium-sized property like ours we have to be a little heavy-handed. I’m all for “letting nature take its course” in large wilderness areas where there will naturally be sections at different stages of succession, but we have to work hard to create and maintain the diversity of habitats we want here.
This kind of thinking leads me to another question that I often think about when I’m out there. How feasible is it to maintain native grasslands here long-term? The Clifton Institute lies on metabasalt (greenstone) bedrock. The soil here is relatively nutrient rich and some spots hold water for a long time. There aren’t as many remnant prairies on metabasalt compared to the poorer soils to our east, apparently because most sites have been converted to agriculture. These richer and moister soils tend to benefit non-native plants, which makes my job harder.
On the Clifton Institute property, we are living with the legacy of hundreds of years of agriculture. The current placement of our fields and forests is dictated by this history, as is the species composition of our plant communities. Moving toward a diverse mosaic of habitats dominated by native species will take time. We will continue to use the tools at our disposal and take cues from the environment to guide things toward greater biological diversity. This is a process that will take many years and will hopefully extend far beyond any of our lifetimes.
