There's a lot more to say about this poem besides the fact that it's a "nature poem." By itself, the term "nature poem" doesn't tell us much. "To Autumn" contains very specific natural landscapes and images. The first stanza offers images of the interaction between humans and the plants that surround them. The second describes the production of agriculture, a natural process that is controlled by people. The third stanza moves outside of the human perspective to include things that are not used or consumed by humans, such as gnats and swallows. This third section captures some of the "wildness" and unpredictability of nature.
Keats portrays nature as if it were a shortsighted person who focuses only on the present time without care or concern for the future.
Despite several agricultural settings, the poem consciously ignores human beings and their activities.