
Native insects and birds need the habitats created by leaf litter, dead stalks and native grasses. Many creatures like butterflies, bees, moths, toads, and salamanders need leaf litter to survive the freezing temperatures of winter. Your plants also need dead leaves for the microorganisms they nurture.

By doing a lighter fall clean-up and accepting a slightly less tidy yard, you can do a lot both for your garden and for the resilience of our threatened native fauna. As the New York Times puts it, think of fall clean-up as an “editing job”, not a wholesale cleanout.
https://www.nytimes.com/2020/09/30/realestate/fall-garden-cleanup.html
