· Climate
In the arctic tundra there are two seasons: winter and summer. In the summer, the sun is present almost 24 hours a day. This sun however, only warms the tundra up to a range of about 3°C to 12°C. In the winter the opposite light conditions are present. There are several weeks where the sun never rises. This causes the temperatures to drop to extremely cold levels. The average temperature of the tundra is around -28°C while extremes can dip to -70°C.
· Precipitation levels in the tundra are from 6 to 10 inches a year. Most of this falls as snow. In many ways this biome is a cold desert, lacking significant precipitation. However, something that many people might find unusual given the lack of rain or snow is the presence of a lot of standing water. This is the result of the permafrost. Each summer, the upper layer melts just enough to create small bogs and pools. The water will not soak into the ground however, because the permafrost blocks it. In the winter these pools freeze and the cycle repeats itself. Very little moisture is lost to evaporation.
· Global Warming
With global temperatures on the rise the tundra will undergo some major changes that end up acting as positive fee. In the summer plants grow quickly, taking in carbon dioxide from the atmosphere. However, this season normally only lasts for a short period. Before any organic mater has a chance to decay, it freezes again. Thus, carbon from the atmosphere is sequestered and locked in the permafrost. However, with global rise in temperatures, the tundra is releasing carbon back into the atmosphere. It no longer acts as a sink.
Alpine Tundra info.
In the late 1800's a man by the name of C. Hart Merriam was surveying the land from the bottom of the Grand Canyon to the top of the mountain peaks. He noticed that distinct plant communities were found as one increased elevation. He noticed that lower elevations were prairies, then dry steppes, Ponderosa Pine, montane forests, subalpine forests and finally the alpine tundra.
He mapped distinct life-zones with elevation. Today we still use Merriam's lifezone classifications.
Alpine Tundra, the highest life-zone
The tallest lifezone, the alpine tundra can be found at any latitude on earth. yet, the elevation that the alpine tundra begins is different depending on where you are.
For instance, on the tall Mexican Volcanos, the treeline is much higher than anywhere in the United states. It occurs around 13,000 feet.
In Colorado, the Tundra begins around 11,500 feet. Farther north, in Alaska, the Tundra can form at onlly a few thousand feet elevation!
Micro-habitats in the Alpine Tundra
The alpine tundra is not a homogenous zone where plants have equal opportunity to grow. Small changes in elevation in this zone and patches of snow and rock create microhabitats where different species of plant and animal can specialize. For instance, a small depression on the ground might decrease sun and wind intensity causing snow to accumulate. Snowbanks are hard places for plants to grow because areas where snow builds up decreases the already short growing season. Thus, small elevation changes that increase light intensity may be just enough for small plants to make a living.
Some of the major micro-habitats found in the Alpine tundra are Meadows, snowbeads, talus fields, and fellfields. You can imagine that plants growing in one habitat are going will need different adaptations to grow in others.
Animal Adaptations
Very few animals are found in this habitat year round. Some of the few that do make thier home here year-round are yellow-bellied marmots, pikas, and ptarmagins. Each has unique adaptations to allow them to live here.
Yellow bellied marmots that live in Colorado will hibernate for as many as 8 months out of the year.
Yellow bellied marmots (hibernate for 8 months of the year). Pikas don't hibernate. They hide from the weather under rocks in the boulder fields. They store food in haypiles and munch them until real food is available. Pikas are related to rabbits and hares, not rodents.
Plant Adaptations:
- Dark colors on alpine plants absorb more heat:
- Anthocyanins: pigments that create red or blue - they convert light into heat.
- Plants are often slow growing. This makes them vulnerable to human impacts.
- Most plants are long-lived perennial plants. They don't grow stems, leaves, flowers and fruite each season.
- Plants are matted against the earth, this keeps them away from the harmfull wind.
- Some plants have hairs, which allow them to trap heat and diffuse the harmfull solar radiation.
- Some plants are succulents, storing water in their leaves (waxy leaves that prevent dessication).
Tundra is derived from the Lappish language and means "land of no trees".
Notable animals in the alpine tundra include, Kea parrots, marmots, Mountain goats, and pika.
Alpine tundra does not map directly to specific WWF ecoregions. Portions of Montane grasslands and shrublands ecoregions include alpine tundra. The alpine tundra also has elks,marmots, mountain goats, pikas, and sheep.
Text by Rob Nelson
