After a recent snowfall, a strange pattern emerged on Zoerb Prairie. What is that lopsided figure? Have aliens landed? Is it a race track? Daytona on a goat prairie? Or did someone from the state of Georgia stamp an image of their state on the bluff prairie for fun?
Well, the answer is that it outlines a refugia. Friends of the Blufflands was planning to burn Zoerb Prairie recently and isolated the area inside the figure to remain unburned. It is now common to leave an area unburned where insects and other critters can survive to repopulate the remaining prairie. This is called a refugia.
Prairies are often referred to as fire-dependent communities. As the name implies, these communities need fire to remain vibrant. Fire is beneficial for many reasons including to remove the build up of thatch, to stimulate the reproduction and growth of some plant species, and to help control the encroachment of woody plants. Most experts recommend that remnant bluff prairies, which are often surrounded by difficult to control buckthorn and honeysuckle, be burned every 2 to 3 years. These burns are often referred to as "prescribed burns" meaning that a prescription of factors need to line up within a range of parameters for the burn to be successful and safe. These ingredients include wind speed, relative humidity, temperature, and recent precipitation. Zoerb was last burned on March 19, 2021.
But what about the insects that live on the prairie? There are estimates that up to 1000-2000 insect species live only in this specific ecosystem, some of which are rare and relatively immobile like leafhoppers. What happens to them when fire sweeps through? This is actually somewhat controversial and much is still unknown, but it is thought by some experts that a certain percentage of insect species might experience at least a temporary reduction in population after a burn. Most of these species recover quickly. But with isolated, remnant prairies that are far from neighboring intact prairies, it is possible that some might have a hard time bouncing back or not recover at all. Hence the refugia. There are, however, many unanswered questions about refugia and the best way to use them. How big should they be? Should they be moved around? Should they overlap from one burn to the next? It is safe to say that most experts feel that the overall benefits of fire in keeping the plant community healthy is more helpful to the vast majority of insects than the few insects that might be harmed. It is also possible that decreasing the insect population might, in some circumstances, be good for the prairie habitat, and therefore good for many insect species in the long run despite a short term decrease in their population. At this time, Friends of the Blufflands plans to move overlapping refugia around from burn to burn to preserve the health of the entirety of this fire-dependent habitat, while giving those rare insects that could possibly be adversely affected a place to hide.
The Prairie Enthusiasts is an organization dedicated to the restoration and protection of prairies, especially those remnants left from the time when the prairies dominated the midwest, and has chapters located throughout much of Wisconsin, as well as into Minnesota and Illinois. The Coulee Region Chapter covers La Crosse and five other nearby counties and has been a valuable partner with Friends of the Blufflands to help manage and preserve our local remnant prairies like Zoerb. They have been very helpful in developing overall management plans, to decide about the inclusion and placement of refugia, and for planning and directing prescribed burns. For further information about remnant prairies, prescribed burns, and refugia, here is a link the to The Prairie Enthusiasts website: https://www.theprairieenthusiasts.org/faqs.
Hopefully, the burn on Zoerb will happen sometime soon if the weather cooperates and the necessary crew is available. And then the aliens will have to land and form another pattern on the prairie in a few years- just not in exactly the same place please!