Read quickly, these lines can seem like scattered thoughts, but they share a mood of weariness and quiet regret. The opening hints at a loss caused by neglecting a friend, and the speaker seems to be counting the cost. The title, Ash Wednesday, suggests a day of penitence, and the ash that turns up in "every well is ash" fits that: even places that should give nourishment feel burnt out and empty.
The speaker's self-image is humble and worn. A face "like an old shoe" is creased, scuffed and past its best. Talking to trees suggests loneliness, or a turn toward the natural world because people are no longer available, though it may also be a way of finding some gentle company.
The ending is the most intriguing part. The speaker says "we have had our winter / but not the fox's," which could mean that the human hardship has been emotional, a season of dryness and distance, while the fox's winter, the literal cold, is still to come. The mood is sober and bare, with a faint sense of endurance.