WebExtra:
Give Him Land, Lots of Land
An interview with Mark McCone, director of Carleton College’s Cowling Arboretum
One of Carleton’s most visible commitments to the environment is the Cowling Arboretum, which consists of approximately 880 acres of land adjacent to the College. Since the 1920s, when it was created under the leadership of President Donald J. Cowling and Professor Harvey E. Stork, the Arb has seen dramatic changes. “People forget that the Arb was a completely agricultural landscape in the 1930s,” says Mark McKone, biology professor and director of the Arb. “There were two working farms and trails for horses—there wasn’t a stitch of prairie left.” McKone became Arb director in 1991 and together with Myles Bakke, Arb manager, began an aggressive forest and prairie restoration project to return the land to its natural state. We sat down with McKone to talk about land management, invasive species, and new Arb residents.
WHAT IS YOUR PHILOSOPHY FOR RESTORING THE ARB?
One of the rules for good land management is to have the biggest area possible. A large habitat attracts more species. In the 1930s, when the Arb’s forest was split into tiny pieces, it was the worst-case scenario because it was all edge (the boundary between natural habitat, such as forests, and developed land). When Myles and I came on board there was a germ of an idea—some small forests started in the 1930s and 1940s and Hillside Prairie started by students in the late 1970s and 1980s. We said, “This is a good idea. Let’s do it, but make it a lot bigger.” It went from a piecemeal approach to doing the whole thing.
WHY IS EDGE BAD?
Many reasons. Raccoons and crows come in from the edge to attack the nests of forest birds. Also, interior forests species can’t tolerate high temperatures or wind or humidity changes. If you have a big chunk of forest instead of a little strip of trees, the middle is protected from the wind and humidity.
WHAT TYPE OF MAINTENANCE DOES THE ARB REQUIRE?
To add to the Arb’s prairie and forest restorations, we have to prepare the sites, remove species that don’t belong there, and plow the fields. As soon as prairie plants produce seeds over the summer, Myles starts collecting them and putting them into storage for planting. That’s a big job because we want a high diversity of plantings. In October we put all the seeds into the ground.
WHAT ARE THE BIGGEST CHALLENGES YOU FACE WITH THE ARB?
Mowing trails is a basic challenge—if we didn’t stay on top of that, they’d close up in no time. And we have a growing list of invasive species—it’s a lot of work to get rid of them. Buckthorn is a huge headache. It’s aggressive and prevents other species from being able to reproduce. We’ll be fighting it forever. But there is progress. I see areas that used to be covered with buckthorn and how much they’ve improved. But it will never go away completely.
WHAT STUDENT OPPORTUNITIES DOES THE ARB PROVIDE?
Students are involved in everything. A student crew works in the Arb. Students worked for me on all my sampling this summer. In my “Population Ecology” class, which I taught in the spring, all students do an independent project in the Arb, as they do in “Field Drawing,” an art course. The geology department is out there all the time, not to mention the athletic department for skiing and running.
HOW DO YOU DECIDE WHAT WILL GO WHERE?
On some level, what’s going to go where in the Arb already has been worked out. Over the years, we’ve made decisions, and we watch what’s happening. My own scientific research is in those prairies. We have 144 long-term, permanent vegetation plots, and every couple of years we map every plant in the plots and make a species list. We also listen to birds pretty regularly.
YOU’VE HAD SOME RARE BIRD SIGHTINGS RECENTLY.
Yes. The Henslow’s sparrow is a rare bird. Talk about edge—it needs big pieces of prairie. When the Henslow’s sparrow showed up, that was a vote we wanted, and it’s here for the second year in a row. We have many other animals now, too: coyotes, turkeys, wood thrushes, and bee and butterfly species.
HOW DO THESE ANIMALS FIND THE ARB?
Birds are mobile, so when they come back from migration they begin to explore. Coyotes are a wide-ranging species. If a habitat becomes appropriate, they’ll probably find it. I worry about other animals that can’t get there. The prairie vole, a little rodent, would be perfect in the Arb, but it’s too small to travel. Some things just won’t find the Arb.
HOW LONG WILL IT TAKE FOR THE ARB TO REACH ITS FULL POTENTIAL?
Forests take about 100 years to mature, and no one knows how long prairies take to mature. Carleton students will be busy forever. But every time an edge-sensitive species—like wood thrushes and scarlet tanagers—shows up, we’ll have a little celebration. We’ll be able to say, “Yes! We created a habitat that is something special.”