As temperatures reached 65°F, Carls took to hammocking, frisbeeing and studying in the Bald Spot this last weekend. Spring has officially arrived in Northfield.
Carleton students aren’t the only ones enjoying the warmer weather. Around the city, hundreds of little blue flowers have sprouted in lawns and the Arboretum a
like. These flowers, while almost perfectly in theme for Maize and Blue Daize, are actually extremely invasive.
Siberian squill are among the first flora to begin their bloom in Northfield. They are extremely hardy and can grow in a variety of locations. According to Nancy Braker ’81, the Puzak Family director of the Cowling Arboretum, invasive plants tend to either have a chemical impact or a spatial impact on their environment.
Garlic mustard, for example, is a non-native species that “has a chemical property that gets in the soil and keeps other plants from growing very well.” The squill’s impact is mainly spatial. While their bloom only lasts for a few weeks, their leaves and quarter-sized bulbs remain.
As a result, “even after they die back, all of those bulbs are underground, just taking up space,” said Braker. The roots of other plants — especially native plants — have nowhere to go.
While student naturalists and Arb staff work to control invasive plant populations, the squill’s resistance to herbicides and dense population makes it difficult to manage. “We just have to let it go … there’s too much of [the squill] to do anything about [it],” said Braker.
But the Arb sees other signs of spring aside from the squill. Woodland wildflowers are also beginning to peak. While the trees have yet to fully leaf out, trillium, bloodroot and some anemone species can take advantage of the sunshine.
Their bloom — like the squill — lasts only a few weeks or as long as it takes for the trees’ leaves to unfurl. Right now, Braker said, “there’s some very beautiful patches of wildflowers along the paved trail where people can see them.”
“Also quite far out in the lower arb, there’s a section called Best Woods, which, when I first started working here, I thought it was named after somebody with the last name of Best, kind of like the Weitz Center,” she said. “Nope, it is named that because it is the best woods.”
Outside of the woods, more flowers begin to show their petals in the grasslands of the Arb. One, the Pasque flower, is specifically named because its bloom often coincides with Easter, which is this weekend. This year, though, the Pasque flowers have been out for a couple of weeks already.
For pollinators like queen bumblebees that are coming out of hibernation, native flowers are important sources of pollen. While it is unknown whether the bumblebees prefer native or nonnative flowers, biological evidence and theory supports the importance of native plants in native habitats.
Alternatively, because bumblebees didn’t evolve alongside nonnative plants, they aren’t adapted to utilize them. Flowers such as the squill better serve the nonnative honeybee due to their smaller size. Honeybees compete with native bees like the queen bumble bee for nectar and pollen sources. “They’re also thought to spread disease to native bees,” Braker added.
In addition to tending to invasive plant populations, the Arb staff begin other important tasks for the transition to warmer weather. Student naturalists, arboretum workers and volunteers made up by the Northfield and Carleton communities are busy preparing parts of the land for prescribed prairie burns.
“Natural prairies require disturbance in order to exist,” wrote student naturalist Gerrit Hoving ’25 on the Arboretum website. “Disturbances such as drought, grazing, and fire prevent the growth of trees and shrubs and are often necessary for the life cycles of prairie plants.”
The prescription burns were historically used by Indigenous populations to maintain the naturally occurring prairies.
According to Braker, “[W]e burn any particular spot in the prairie maybe every four years, so there’s that many years of accumulated leaf litter.” These chosen spots are small, and preparation is completed to ensure that the fires will be conducted and contained safely.“ It takes much longer to create [them] than it does to actually do the burn.”
Additionally with the migration of birds starting to peak, the Arb hosts an annual spring bird count — this year on May 17 — to contribute to data sets that track bird populations, especially prairie birds, which are threatened by the loss of habitats. Such data sets inform the Arb’s prairie restoration efforts.
In a 2018 account, student-naturalist Andy Hoyt ’19, wrote that due to restoration efforts, “many of these bird species have begun to show up more and more frequently in the annual Bird Counts.”
Spring in the Arb is a time of transition as flowers grow and birds return. For the workers, this time is both busy and a chance to reflect on the progress and future of natural habitat restoration.
