Alpine tundra occurs on mountaintops above the treeline. It is a windswept environment with plants adapted to short and harsh growing seasons. Alpine plants are perennial and grow close to the ground to tolerate wind, sice and snow. Due to topographic complexity, many different community types are found in the alpine over short distances. For example, long-term sampling at the Niwot LTER includes a 350 x 500 m grid across a saddle, which includes plots characterized as wet meadows, snowbeds, dry meadows and fell fields. Some alpine plants span nearly all of these habitats, while others are specialize on certain community types.
In part due to habitat heterogeneity, alpine tundra supports a high diversity of wildflowers, grasses, sedges, cushion plants, mosses and lichens. Although remote from human development, alpine tundra is increasingly shaped by human influence. For example, grazing has been historically common in the alpine, and the system is sensitive to global change factors such as nitrogen deposition and warming.