Counting The Stems: Understanding the Milkweed Population at The Confluence

Written by: Ken Forbeck (August 2022)

One of the prides of our work at Nature At The Confluence is the ecological restoration of this site, especially the growing milkweed population throughout the prairie. When our organization was started in 2017, there were reportedly only 10 stems of common milkweed located on the edge of the prairie. Since then, we have recruited volunteers and visitors to help us spread common milkweed seed in the prairie and plant milkweed in our pollinator gardens. As we continue with these efforts, we want to understand how much milkweed is actually in the prairie and further investigate the impact our efforts have had in the restoration of the prairie.

In July 2021, I started the first documented count of milkweed around our prairie with a roughly drawn map and a curious mind. With the help of a volunteer, Mari Weikel, I tallied up 369 stems of milkweed, consisting of common milkweed and butterfly weed. Due to the current prevalence of these two species throughout the prairie, we have solely focused the efforts of this study on those species, although there are a total of 24 species of milkweed in Illinois. With that data we could then look at the prairie and understand how abundant these two species of milkweed were in 13 different sections of the prairie.

This past July I conducted another milkweed count with our AmeriCorp Member Ani Adhikary. This year we decided to record the stems of common milkweed and butterfly weed separately in order to understand how both species are growing in the different sections. This count concluded that we now have approximately 945 stems of milkweed total, including 796 common milkweed and 149 butterfly weed. This showed more than a doubling in milkweed in the prairie just in the past year!

Through this experience, I was able to see patches of milkweed expand and new ones appear during this second year. This gave me a particularly unique and intimate view of the impact our efforts and some time passing had on the milkweed population in the prairie. Areas where we had removed invasive species or conducted a prescribed burn showed a marked increase of milkweed, our stewardship practices are making a positive impact. Some areas had notable increases such as more than 262 new found stems of common milkweed just to the northwest corner of the parking lot. We also noticed an increase of only butterfly weed next to the railroad east of the center, likely since it can thrive in the dry rocky soil there.

Ensuring the prairie has a growing milkweed population is more important than ever for the creatures that depend on it. The migratory monarch butterfly, whose caterpillar stage relies on milkweed as their sole food source, was listed as Endangered on The International Union for Conservation of Nature Red List of Threatened Species citing habitat loss and climate change as reasons for their decline. With the endangerment of this aesthetic pollinator species, we are glad to see that we are successful in creating and expanding habitat for monarchs when they need it most.

If you want to do your part to help the monarch butterfly and other species that rely on milkweed species, come down to the center during our open hours and grab some common milkweed seeds to grow in your own garden or yard! Avoiding the use of chemicals in your yard is another great way to protect monarchs and other important pollinators.