As The Seasons Change...
Most people I know love Autumn. The changing colors of the leaves, the upcoming holidays, back-to-school, pumpkin spice, cooler weather....there’s a lot that changes with the changing seasons. The same holds true for ecological work. The turn of the season marks a shift in our work at NRP, and autumn in particular often yields a host of new projects.
As summer yields to winter, our focus shifts from herbicide application to cutting. As plants go dormant, spot spraying to treat invasive species is no longer effective. Only species that stay growing for a long time before going dormant, like common buckthorn, are treatable with herbicide in the autumn. So we cease our prairie maintenance and shift towards buckthorn treatment and removal. Fall and winter are prime opportunities for buckthorn and woody species removal. The frozen ground allows us to access sites we wouldn’t otherwise be able to, and prevents our crews and equipment from compacting the soil too much. Plus, most species do not go to fruit or seed over autumn and winter, so we can remove them without risk of spreading seed. So as the days get shorter and cooler, you’ll find our crews hanging up the herbicide backpacks and pulling out the chainsaws.
The Fall season also ushers in the end-of-year burn season. In Minnesota, there are two times of the year when prescribed fire is an effective tool for ecological restoration. October through November is one of those times. As temperatures and humidity drop, we find a sweet spot where fire will still start and carry well, but not get so hot as to be dangerous. Also, most of the native plants have pulled their energy stores into their roots in preparation for the winter. So fire in fall allows us to kill the surface vegetation, letting it return as ashy nutrients to the soil, while not harming the plant which has most of its energy in its roots. NRP often conducts prescribed burns in the autumn, balancing the timing of burns with vegetation dormancy, weather, and impending snowfall.
Dormant seeding also occurs during this season. Dormant seeding is a technique common in restorations that involves laying seed in the autumn, typically October through November. This may seem counterintuitive; after all, don’t seeds need warmth, light, and moisture to germinate and grow?--and many of those are not present in the upper midwest in winter. This is all true, but this is also the reason we seed in fall. When we seed in autumn, the heavy snowpack of the following winter helps press the seeds into the soil, increasing seed-to-soil contact necessary for germination. Additionally, the melting snow in the spring gives the seeds all the moisture necessary to begin growth. The seeds can begin growing as soon as the soil warms up, giving them a full growing season to establish. This often gives these species a competitive edge on other seed that is released in spring or summer which only has part of a growing season to establish. Dormant seeding is easy to do, even if you’re not a trained professional. The key is to get the seed on the ground when the soil is below 50 degrees Fahrenheit, as the seed won’t germinate when it’s that cold; instead, it will sit dormant for the winter, sprouting in earnest come spring.
With all these different kinds of projects happening, don’t be surprised if you see us scampering around like busy beavers. Just as the habitats we love so much change and shift in response to the upcoming winter, you’ll find us changing and shifting right along with them. We hope you get to enjoy the autumn season as much as we do, and get outside to enjoy the great spectacle that is a dynamically shifting landscape in the Fall.