May I draw on my polar experience and offer a slightly different interpretation.
From the short extract quoted, I would take the setting to be Arctic Tundra. Not sure about the 'rim' which could be a lake shore or a sea shore.
To me, I interpret 'gloves' as 'blankets' or 'envelops', meaning to gently cover.
Sheet-ice implies a continuous flat sheet of ice such as that which forms on ponds, lakes and still seas.
Sedge is a short grass-like plant that grows in moist peaty ground.
In arctic tundra, willow does not grow as trees, but grows over the surface of the ground, closely hugging it and with short branched upright stems. Overall, it resembles the moorland heather that you see in the UK.
The whole piece then reads to me as the narrator sitting at the shoreline of a frozen expanse of water where sedges grow. The air is still and a silence blankets the whole area suggesting isolation from civilisation. The higher ground behind the narrator is covered in low willow trees.
Now that may be totally wrong. I am placing that short extract in the context of my own experience, but the rest of the poem may locate the narrator as being somewhere else entirely.
I hope that is helpful to you.