(A version of this article appeared in the Aug. 2016 edition of Ripples, an internal newsletter of The Center at Donaldson)
When you look out at a wetland in the summer, you’ll see a flush of green, hopefully colored with dashes of yellow, blue, pink, or white. But how can you tell if a natural area is “healthy?” What are indicating that it might be “sick” or “degraded”? While ecological health cannot ever be boiled down to a single number, there are several tools that ecologists use to rate the health of a natural community. The presence or abundance of certain plants or animals can even give us a clue as to the site’s history.
This is why Sr. Mary Baird and I were excited to come across a dainty, narrow-leaved, 5-petaled yellow flower as we were exploring a wetland on PHJC land. I could tell that it was a loosestrife of some sort, so I took some photos and notes so that I could identify the plant back with the resources back in my office. I then e-mailed Sr. Mary excitedly, “It’s a C 10! Prairie Loosestrife, Lysimachia quadriflora.”
A C-what? I was referring to a numbered scale, from 0 – 10, called the Coefficient of Conservatism. Each plant has been assigned a number, a “C-value,” by a panel of botanical experts. These values represent the species’ tendency to represent a specific, undisturbed natural community characteristic of the land before the European settlement. (See the foundational paper for Indiana C-values here).
Dandelions, for example, have a C-value of 0 and are found pretty much anywhere soil is disturbed by foot traffic or mowers. Swamp milkweed has a C-value of 6, and are as easily at home in a roadside ditch as a high-quality wetland. Prairie loosestrife tops out the scale at 10. It is “conservative” and doesn’t like change and disruption. Finding a single diminutive plant indicated to us that the wetland we were searching may have other treasures – complex networks of soil, microbes, insects, and other “conservative” plants. Of the 88 plant species we identified, four had C-vales of 8-10.
The Prairie Loosestrife also indicated that this former cattle pasture might have contained a fen, which is a unique wetland type that is fed year-round by groundwater through calcium-rich soils. While rebuilding a rain-fed marsh is fairly straightforward, this particular network of underground hydrology is so complex that scientists have been unable to reconstruct these communities of fen plants, soils, and microorganisms. As a fellow ecologist once told me, “Humans don’t create fens. Ice ages create fens.”
We will be working over the coming years to reduce the weedy, invasive plants that took over much of this wetland when it was used as a cattle pasture. We are hoping that dormant seeds of even more unique fen plants will spring forth as new opportunity is given for growth. Who knows what you and I will “C” next?!