Spring is springing in Minnesota. Everything smells earthy and like thunderstorms and wildflowers and… fire? Spring in Cowling Arboretum means it’s time to burn! Controlled burns are an integral part of Carleton’s ongoing prairie restoration project. Disturbance is an important mechanism within Midwestern prairie ecosystems. Historically, drought, bison, and fire intentionally set by Native Americans were the main methods of disturbance. Since bison have not been sighted in the Arb for a very, very long time and drought cannot be induced, we are left with fire to create the disturbance necessary to keep these systems thriving.

Fire keeps tall grass prairies healthy in a number of ways. These ecosystems are fire-adapted since they have evolved with the presence of fire over the past 10,000 years. Burning helps return nutrients bound up in dead grasses to the soil which leads to increased flowering, fruiting, and seed production. The year after a burn is a particularly productive one for these prairies. Fire also helps with the germination of some prairie species, and both the fire-warmed soil and heat-absorbing black ash helps jumpstart growth earlier in the Spring. Additionally, most invasive competitors, such as buckthorn, are not fire-adapted and get burned off.

It’s important to know what you are doing when setting a prairie fire. Edges need to be mowed and raked, fire brakes must be established, and equipment for controlling the fire must be available. The arboretum is divided into sections that are burned approximately once every four years. This gives land the benefits of burning while leaving plenty of time for the prairie to regrow.

 PSA: Want to get involved with the Arb? Just like being outside? Then the Annual Carleton Bird Count this Saturday the 16th is for you! Whether you are a first time birder or an old pro we would love to have you along. We’re meeting at the Arb Office next to Farm House at 6am.