Tundra is a type of biome characterized by low temperatures and a short growing season. Tundra vegetation is characterized by dwarf plants like mosses, lichens, grasses, sedges, etc. Trees are usually absent in this biome. The three types of tundra are mentioned below.
3. Arctic Tundra
One of the most pristine environments on Earth, the Arctic tundra exists as vast stretches of landscape devoid of trees and with permafrost as subsoil. Arctic tundra is found north of the taiga belt in the far Northern Hemisphere. It covers large parts of Russia and Canada. The subsoil in this region is frozen throughout the year. There are two seasons in the region, summer, and winter. Winter is characterized by extremely low temperatures with an average of around −28 degrees celsius. Even the top layer of soil freezes during this season. Daytime temperatures in summer rise to about 12 °C but can also drop to below freezing on certain days. During summer, the topsoil thaws creating a soggy ground. Seasonal marshes, bogs, lakes, and streams thus form across the Arctic tundra landscape in this season. High winds blow in the Arctic tundra. Wind speeds as high as 50 to 100 km per hour blow here. Precipitation is extremely low in the range of 150 to 250 mm per year. Evaporation is also minimal.
Tundra plants grow and reproduce during the summer. Plants found in the tundra are limited due to the extreme conditions. Trees are completely absent as the roots cannot grow beyond the topsoil due to permafrost. Mosses, lichens, and heath are the only types of vegetation found in the Arctic tundra. Only around 1,700 species of vascular plants grow in this region. The diversity of fauna is also low. Only 48 species of terrestrial mammals like reindeer, Arctic fox, musk ox, Arctic hare, etc., live in this harsh environment. Polar bears can be seen near the coastlines. A variety of migratory birds, however, can be seen in the Arctic tundra during the summer season when the seasonal marshes, lakes, bogs form. The snowy owl is one of the most notable birds of the tundra. Poikilotherms or cold-blooded animals are almost completely absent in the Tundra region.
Human presence in the Arctic tundra is also minimal. Those who live here are mostly nomadic reindeer herders. Little human activity is also seen in the region although it is rich in natural resources like uranium, petroleum, and natural gas.
2. Antarctic Tundra
The Antarctic tundra spreads across the continent Antarctica and several Antarctic and subantarctic islands. It is the coldest region on Earth with temperatures dropping well below - 50 degrees celsius. Antarctica is also extremely dry with an average of only about 166 mm of annual precipitation. Permafrost covers most parts of this region. Large ice caps and glaciers cover the entire landscape. High-speed winds also blow in the region.
Most of the Antarctic tundra region is too cold to support any form of vegetation. Rocky soil in some parts of the Antarctic Peninsula, however, have some plant life. Around 100 species of mosses, 400 species of lichens, 25 species of liverworts, and 700 algae species grow on the exposed soil along the coastal regions. Two flowering plants, the Antarctic pearlwort, and the Antarctic hair grass also grow here. Unlike the Arctic tundra, the Antarctic tundra lacks any terrestrial mammalian species due to the isolation of the continent from the rest of the world. Sea mammals are, however, found in the offshore waters in large numbers. Seabirds including large colonies of penguins also thrive in the area.
Human settlement in the Antarctic tundra region is limited to scientific, meteorological, and military outposts representing different countries. No permanent human habitation is present in the Antarctic region with the exception of those living there with special permission for specific reasons.
1. Alpine Tundra
Unlike the polar tundra regions mentioned above, the alpine tundra is characterized by a lack of trees due to high elevation. As latitude increases, the height at which alpine tundra vegetation is found decreases until it merges with the polar tundra regions at sea-level. For example, alpine tundra in the South Asian Himalayas will occur at a higher altitude than that in the Alps of Europe which are located at a higher latitude.
Alpine tundra is the region between the tree line and snow line of mountains. The climate here is frigid and decreases with altitude above sea-level. The climate in alpine tundra is less uniform than that in the polar tundra due to the undulating terrain of the mountains with ridges, valleys, ice caps, glaciers, and other features. However, growing seasons are usually very short (45 to 90 days) and have a temperature of around 10 °C but can drop to below freezing on several occasions. Frost is also common during this time. Most precipitation is in the form of snowfall, especially in winters. High winds also blow and erode soils easily. Such winds combined with high solar radiation also increases evaporation and transpiration rates from plants.
Dwarf plants like perennial grasses, sedges, cushion plants, and forbs grow in the Alpine tundra region. The plants grow close to the ground. Fauna in the Alpine tundra is highly varied depending on location. Some animals found in such regions include Himalayan tahr, yak, pika, marmot, mountain goat, kea, etc.