How is nature presented in 'To Autumn' by John Keats?

The poem observes the natural world in autumn by delineating a number of sights, sounds, and pastimes that place humans beings squarely in the season's midst. There is also a theme of nature's providing a bounty of food and drink for human consumption. The description of fruits on the trees and vines is related to descriptions of reaping, winnowing (grain) or pressing cider from apples: all activities are related to the production of food or drink. In this way, the poem celebrates the abundant gifts of nature, and the deep and vital connection humans have to the natural world; as the poem suggests, without these foods provided at harvest time, we would experience hunger and thirst. But the poem also hints at the sensual pleasures of these activities, and the ways in which autumn (and more specifically, nature in autumn) engages all of our senses, particularly with sounds and songs (as with the third stanza, referring to the "songs of spring" and the sounds of birds, lambs and insects). In crafting lines that immerse the reader into this complex realm of sensual pleasure, the poet creates many visual and aural points of reference that could possibly inform the reader's future thoughts of autumn, every year when it returns, making this observance an ingrained part of one's life experience, underscoring the centrality of nature to human existence.