Given the task definition and input, reply with output. In this task, you're given passages that contain mentions of names of people, places, or things. Some of these mentions refer to the same person, place, or thing. Your job is to write questions that evaluate one's understanding of such references. Good questions are expected to link pronouns (she, her, him, his, their, etc.) or other mentions to people, places, or things to which they may refer. Do not ask questions that can be answered correctly without understanding the paragraph or having multiple answers. Avoid questions that do not link phrases referring to the same entity. For each of your questions, the answer should be one or more phrases in the paragraph, and it should be unambiguous.

Passage: Grand Teton National Park and the surrounding region host over 1,000 species of vascular plants. With an altitude variance of over 7,000 ft (2,100 m), the park has a number of different ecological zones including alpine tundra, the Rocky Mountains subalpine zone where spruce-fir forests are dominant, and the valley floor, where a mixed conifer and deciduous forest zone occupies regions with better soils intermixed with sagebrush plains atop alluvial deposits. Additionally, wetlands near some lakes and in the valley floor adjacent to rivers and streams cover large expanses, especially along the Snake River near Oxbow Bend near Moran and Willow Flats near the Jackson Lake Lodge. Altitude, available soils, wildfire incidence, avalanches and human activities have a direct impact on the types of plant species in an immediate area. Where these various niches overlap is known as an ecotone.The range of altitude in Grand Teton National Park impacts the types of plant species found at various elevations. In the alpine zone above the tree line, which in Grand Teton National Park is at approximately 10,000 ft (3,000 m), tundra conditions prevail. In this treeless region, hundreds of species of grass, wildflower, moss and lichen are found. In the subalpine region from the tree line to the base of the mountains, whitebark pine, limber pine, subalpine fir, and Engelmann spruce are dominant. In the valley floor, lodgepole pine is most common but Rocky Mountain Douglas-fir, and blue spruce inhabit drier areas, while aspen, cottonwood, alder, and willow are more commonly found around lakes, streams and wetlands. However, the tablelands above the Snake River channel are mostly sagebrush plains and in terms of acreage is the most widespread habitat in the park. The sagebrush plains or flats have 100 species of grasses and wildflowers. Slightly more elevated sections of the plains of the northern sections of Jackson Hole form forest islands with one such obvious example being Timbered Island. In this ecotone, forested islands surrounded by sagebrush expanses provide shelter for various animal species during the day and nearby grasses for night time foraging.
Besides the Rocky Mountains subalpine zone, what are three ecological zones in Grand Teton National Park?