Book excerpt: The Colorado Rockies are Ann Zwinger's subject in prose and drawing. There, 8,300 feet above sea level, summer is short and winter long and often harsh; it is a place where much of life exists on the margin. In good years the grasses are lush; in bad years, even the mice starve. But it is a land the Zwingers have lovingly explored and recorded, careful not to disrupt the balance of the land, the relationship of plant to animal and of each to its environment.These forty acres, called Constant Friendship after the Maryland land her ancestor settled in the early 1730s, are a place of all seasons, for even in winter there is a promise of spring, and in spring the foretaste of summer. The white of snow becomes the white of summer clouds, the resonant green of spruce becomes the green head of drake mallard ... here part of each season is contained in every other.In beautiful and simple language and with 80 illustrations, Beyond the Aspen Grove tells of meadow, lake, marsh and forest, of algae and dragonflies, of deer and jays that live in the thin clear air of the mountain world.