Figure BE.50 tundra vegetation (Photo credit: Michael Ritter)

Vegetation consists of low growing shrubs, cushion plants, small forbs exploding with colorful flowers and lush meadows of sedges and grasses. These plants cover gentle slopes and rock crevices. Rock surfaces are dotted with a cover of lichens and mosses. Most species are slow-growing perennials. Plants have been forced to adapt to such an extreme environment. Ninety percent of total structure in some plants is in roots storing nutrients and energy during poor growing periods. Flowers are often large but other parts of the plant are small to save energy, and reducing exposure to the rigors of the wind. Some plants have waxy coatings or hairs thus losing minimal heat and water to the wind. The location of plant communities is correlated with the duration of snow cover. While snow is blown free from exposed sites, it accumulates in the lee of obstructions and in depressions. Community location is also related to soil, drainage, and movement of soil by burrowing animals, and frost action which is prevalent throughout much of the alpine tundra. Dense willow thickets often occupy moist depressions on the lee side of ridges. A deep cover of snow during the winter protects buds from the wind and freezing temperatures. These are the tallest perennials growing above the krummholz of the ecotone.

Figure BE.51 Alpine tundra fell field (foreground) and on rocky knoll ( upper right)   Colorado, USA. (Courtesy UNESCO)

Fell fields are colorful  rock gardens exposed to the rigors of the wind. Wind removes snow throughout the season subjecting the plants to desiccation. Low-lying mats and cushion plants nestle against the rocky surface.

Figure BE.53 Solifluction terraces with snow lying behind. (Photo credit: Michael Ritter)

Soils are quite variable, from barely any soils in valleys scoured by glaciers to the mature residual soils of unglaciated ridges, and scattered in between rocks brought to surface from frost heave to form periglacial features like polygons. Soil ice is found in all soils in winter, and soil temperatures are low enough to form patches of permafrost. A common landscape feature of the tundra are solifluction terraces. Solifluction terraces with willow growing on top and to the back are visible in the center of the photograph. Late lying snow patches keep conditions moist to permit willow growth. Reaching a few feet high, willows are covered by snow to protect the over-wintering buds. Willows are the tallest of any species in the alpine tundra.

Figure BE.54 Polygon, outlined in black, caused by frost heave. (Photo credit: Michael Ritter)

The plant communities mentioned above are considered climax communities mainly because they change so slowly. Communities are often disturbed by small burrowing animals like the pocket gopher that churn up the soil and eat plant roots, or voles which can devastate above - ground biomass. Recovery after disturbance proceeds exceedingly slow, slower than any other mountain ecosystem.