Answer:
The winter setting creates a vivid scene - Dark spruce forest frowned on either side the frozen waterway.
The place in question is described as having a dark spruce forest that frowned on either side of the water way. This is a vivid description due to the use of the word ''frowns''. This description paints a vivid picture in the mind of the reader as they imagine a frowning forest.
The tundra is isolated and still - A vast silence reigned over the land.
In stating that there was a vast silence that ruled the land, the author is describing a silent place which means that it is isolated.
Even in the midst of winter, there is action on the tundra. - But there was life, abroad in the land and defiant.
The presence of life however that was defiant and had learnt to live on the land showed that there was still some action on the tundra even in winter because as already mentioned, the life forms were defiant.
The environment requires special equipment. - It was made of stout birch-bark, and its full surface rested on the snow.
By stating that the full surface of the area rested on the snow, the author is trying to convey that moving on the land can be very hard due to all the snow. Special equipment is therefore needed for transport.