Used first paragraph of the chapter: Moisture is one of the premiere limiting factors for plants and animals, and where moisture is not limiting-in streams, marshes, lakes, and the land areas adjacent to these features (the riparian zone}:-one finds very distinctive communities of water� dependent and drought-intolerant species. Major streams in the foothills and basins of the San Juan region are commonly lined with riparian woodlands dominated by cottonwoods (Populus spp.). These wood� lands and associated phreatophytic vegeta�tion (composed of plants that require a perennial water source near the soil surface) have changed dramatically during the latter half of the nineteenth and the twentieth centuries on the western Great Plains [...]
