Tundra

Tundra is a generic name for a low-growing ecosystem found in climatically stressed environments with short and cool growing seasons. Latitudinal tundra occurs in the Arctic and to a much lesser extent in the Antarctic, where the environments are characterized by cool, short growing seasons. Altitudinal tundra occurs under a similar climatic regime, but at the tops of mountains.

After temperature, the second most-important environmental factor affecting most tundra communities is moisture. Under wet conditions, sedge and grass-dominated meadow communities develop, while moist conditions favor a vegetation dominated by dwarf shrubs and herbaceous species, and dry sites have cushion plants and lichens. The vegetation of arctic and alpine tundras share many structural characteristics, most genera, and some species. However, there are important environmental differences between these two tundras, with the alpine type being subject to much larger variations of daily temperature during the growing season, as well as more intense inputs of solar radiation during the day. In contrast, arctic tundra can experience continuous exposure to the sun's rays, with 24-hour days for an extended period during the growing season.