The thorough descriptions of fall create a melancholy mood and a sense of something coming to an end. The farther you read in the poem, the closer you get to a sad ending, and the melancholic mood of the whole thing builds the farther you go. In the second stanza specifically, the word 'lo' is used in a longing way. The last two lines seem to be asking the reader if they can still smell the scents autumn brings with it.
