Novel ecosystems are no longer new thanks to humans

Anybody who has seen me walking with a cane knows that I'm not exactly a spring chicken. Some might joke that my social life is an example of carbon dating. As an aging example of Homo sapiens, I'd like to reflect on our species' impact in the natural world we inhabit.

Terms defined

The place where a population of organisms, like frogs in a pond, lives is its habitat. Populations of different species (e.g. frogs, fish, herons) in a particular location is a biological community.

An ecosystem is a community of different species interacting with one another and their nonliving environment of matter and energy. I emphasize nonliving since some folks forget that abiotic components, such as soil nutrients, precipitation, and wind are part of ecosystems.

Now, a novel (new) ecosystem is a system of abiotic, biotic, and social components that, by virtue of human influence, differ from those that prevailed historically. This does not mean that once humans arrive, the ecosystem stops functioning.

In fact, these ecosystems have a tendency to self-organize and manifest novel qualities without intensive human management. Simply put, functional novel ecosystems are all around us and we are part of them.

Urban peregrination

Little did I know when I started Chicago's peregrine falcon release project back in the 1980s, I was working in what would later be called a "novel ecosystem." At the time, I was trying to restore a federally endangered species.

Scientists from Cornell University learned that peregrines, usually cliff nesters, would adapt to the cliff-like ledges found on tall buildings. The falcons had done so in other cities, and I was responsible for getting them to accept some of Chicago's buildings.

Let's recall that Chicago was, essentially, built in a swamp. There weren't any tall geologic formations that eroded away to become the Sears Tower or the Tribune building. These edifices and this falcon habitat were built by humans.

Oh yes, what are peregrines, dedicated bird hunters, eating? While they do eat a variety of avian prey, pigeons are a common meal. These would be pigeons that originally came from Europe and are now permanent residents of many North American cities.

In Chicago and elsewhere, peregrines have long since been taken off the endangered list and are doing well on their own ... as long as we are careful with the chemicals we use where the falcons live. The peregrine falcon is at the top of a functional food chain in this novel urban ecosystem.

A cardinal example

How about our state bird, the northern cardinal? This species must have been here in Chicagoland when us white folks started moving in. Actually, it wasn't. When Illinois became a state in 1818, seeing a cardinal in northern Illinois would have been highly unusual.

Before European settlement, the misnamed "northern" cardinal was more of a southern bird. One study in the Show-Me State summarized the cardinal's northern range expansion nicely: "In Missouri, significant increases coincided with conversion of forest and prairie to park and residential land."

Our redbirds are just another example of a species that fills an ecological role in a novel suburban ecosystem.

Here at Stillman

Right outside my window is another example of a novel habitat; Stillman Nature Center's pond.

In his latter years, Alexander Stillman let nature slowly reclaim the once-formal landscape of his estate. We have largely continued this hands-off policy around the pond. This means the pond is slowly filling in and becoming shallower and, one might argue, returning to what it once was.

A review of old maps does not indicate a pond of this size being here. Some maps suggest a small cattail marsh, that's it. Apparently, the Stillman family had the marsh dug out and enlarged into a small lake.

If you walk around the pond, you will notice that there is a steep slope at the pond's south end. This is not natural, it is an impoundment. This small earthen dam makes Stillman's pond possible.

With the exception of removing purple loosestrife, we do little management near the water. If it is dry, like it has been, the water level drops. We don't raise it. So be it.

I can tell you that frogs, dragonflies, ducks, and herons use this pond like they would any other small body of water, whether it was dammed by humans or beavers. It's just another example of a so-called "novel" ecosystem.

Anthropocene Epoch

The more you look around, the harder it is to find any natural community that is free of human influence. In fact, many geologists argue that we are in a new geologic epoch that should be named the Anthropocene because of our species' global impact.

The current epoch, the Holocene, includes 12,000 years of relatively stable climate since the last Ice Age. Human civilization developed during this time. Since the mid-20th century, some experts argue, the abrupt acceleration in carbon dioxide emissions and sea level rise, the global mass extinction of species, and the transformation of land by deforestation and development mark the end of the Holocene.

The Earth is so profoundly changed that the Holocene should give way to the Anthropocene.

What geologic evidence should be used to mark the beginning of the Anthropocene? The substantiation of humanity's impact on the planet is overwhelming, but the changes are very recent in geological terms.

Traditionally, an epoch spans thousands of years. Carbon dating, more accurately called radiometric dating, allows us to peer back that far in time. A criticism of the Anthropocene epoch is that it is too short of a time frame. The response is that many of the changes are, geologically speaking, carved in stone. A list of these changes would include:

• A layer of radioactive elements from nuclear bomb tests, which were blown into the stratosphere before settling down to Earth.

• An ubiquitous layer of microplastic particles in our waterways and oceans that will likely leave identifiable fossil records for future generations to discover.

• A permanent layer of other airborne particulates in sediment and glacial ice such as black carbon, concrete, and aluminum.

• Increased levels of climate-warming carbon dioxide in the atmosphere at the fastest rate in 66 million years. Fossil-fuel burning is pushing levels from 280 parts per million before the industrial revolution to 400 ppm, and rising today.

• Double the nitrogen and phosphorous in our soils in the past century thanks to dramatic increases in artificial fertilizer use. This is likely to be the largest impact on the planet's nitrogen cycle in 2.5 billion years.

A bone to pick

Undoubtedly, Homo sapiens have made a lasting impression around the world. When it comes to our leftovers, even the bones spread by the global proliferation of the domestic chicken are now under scientific examination.

Given this geologic perspective, I think it may be time to retire the term "novel ecosystem." Might I suggest "actual" or "real" ecosystems? Because, they sure ain't "novel" anymore.

• Mark Spreyer is the executive director of the Stillman Nature Center in Barrington. Email him at stillmangho@gmail.com.