Prescribed Burns on MPF Prairies

December 3, 2021 | Blog

Why does MPF burn its prairies? Prairies and other native grasslands in the Midwest and many other areas of North America evolved with fire. In this geography, relatively ample rainfall supports more than herbaceous vegetation—it also encourages woody plant growth. Without regular fire, prairies would grow up into trees and shrubs, lowering overall biodiversity. Fire helps set back many tree and shrub seedlings. Fire also consumes dead herbaceous vegetation, which facilitates the movement of wildlife during the next growing season, helps control some non-native herbaceous plants that can invade prairies (like tall fescue), and allows more sunlight to reach the ground, speeding up new plant growth in spring. Fire also enhances native plant flowering rates, which is important for pollinators and also native seed germination.

Why do we burn one-third to one-half of our properties each year? There are several reasons why we don’t burn an entire tract at one time. One, just as some wildlife (like grasshopper sparrows) need more open native grassland vegetation during the growing season, others (like Henslow’s sparrows) need denser vegetation in spring and summer, which past growing season thatch helps provide. Two, there are many native bee larvae developing in stems of standing dead vegetation over winter, as well as caterpillars of regal fritillary butterflies and other insect larvae overwintering in leaf litter. Three, wildlife that use prairies in winter—like short-eared owls, rabbits, and quail, just to name a few—benefit from the cover and seeds of standing dead prairie grasses and wildflowers.

Why do we burn in fall through winter? Historically, in this part of the world, most prairie burns were set by Native Americans and they occurred during this time of the year. This new article “Patterns of Anthropogenic Fire within the Midwestern Tallgrass Prairie 1673–1905: Evidence from Written Accounts” was recently published in the Natural Areas Journal and documents evidence that a two- to three-week period during October and November was the primary wildland fire season in the time period 1600-1850. (With global climate change, this season of burning historically noted as “Indian Summer” during October-November may be shifting later into the fall and winter months due to a longer growing season.) This season generally provides the ideal conditions for burning when leaf fall and frost-cured herbaceous vegetation are most flammable.

We aim to have all prescribed fires completed by mid-March depending on the phenology of the spring. In some springs, bud burst and animal activity comes a week or two earlier or later. We want to avoid impacting amphibians and reptiles when they become active, as well as new emerging vegetation.

MPF depends on volunteers to help us carry out prescribed burns—and we are very grateful to them! If you would like to help us, please fill out this volunteer form.

Photo above of prescribed burn at MPF’s Linden’s Prairie by Jerod Huebner.

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