<n season in the Arboretum. Maybe you’ve smelled it when the wind shifts and draws the scent of burnt prairie grasses across campus. Burning is visible in the blackened patches in Lower Arb from the hill past the Memorial, and even a small patch next to the baseball fields.
Prescribed burning is a part of Carleton’s prairie management system and occurs every spring. The Arb is divided into different burn units which are on a rotating burn schedule of every 3-4 years. This means that some prairie is burnt every year, but much is left undisturbed.
Burning is the only consistent disturbance of the Arboretum prairie ecosystem. Disturbance, especially that which exposes bare soil, is essential for prairie health. Burning is beneficial in a few ways. Bare soil exposed by burning provides an opportunity for seeds to germinate and renew prairie plants. The dark ash left behind a burn absorbs more heat from sunlight, encouraging seedlings to sprout earlier in the spring. Additionally, the ash fertilizes the prairie by releasing the nutrients bound up in dead grass stems back to the soil. This is why abundant growth and wildflowers are typical of the season after a burn.
A healthy prairie means a healthy prairie ecosystem. Without disturbance, a single prairie plant (native or invasive) can take over too much area in the prairie. This cuts down on ecosystem diversity and health.
On a walk past some of the burnt areas, you already can see the new grasses popping up, responding to an ecological boost fueled by prescribed burns.