You don’t say how big the area is that you are working with or whether it is a mix of weeds and sod or just weds. You do say you have buckthorn so some of them are woody invasives. These will probably take several removal attempts. 

https://www.dnr.state.mn.us/invasives/terrestrialplants/woody/buckthorn/control.html

https://extension.umn.edu/natural-resources-news/controlling-buckthorn

You may want to try solarization for wide swaths that get plenty of sun. This will take some time but can be very effective if you have large areas with many kinds of weeds.

https://extension.umn.edu/planting-and-growing-guides/solarization-occultation

https://extension.umn.edu/find-plants/weeds

I hope these links help you in your planning and planting of a wildlife friendly yard.