Tundra is defined as a treeless plain of the Arctic and subarctic that has permanently frozen subsoil called “permafrost.” It is generally dominated by mixed vegetation of mosses, lichens, and dwarf shrubs. The perennially frozen ground can be anywhere from a few inches to a few feet below the surface. While the ground below remains froze all year, the top layer that melts under the summer sun is called the active layer. It is here where the shrubs, wildflowers, and grasses grow quickly during the few summer months. Since the ground below remains frozen, water can not penetrate which is one reason the tundra is often wet and boggy. Since tundra is widely distributed across Alaska, the tundra photos here are from all parts of the state and are available for purchase as stock photography, or as fine art prints to display in your home or office.
Features of the Tundra
Tundra is a mosaic of spongy wetlands, marshes, lakes, ponds, and streams. It hosts some unique topographical features formed as a result of repeated freeze and thaw cycles. The cold winter causes the soil to shrink, crack and buckle. When it melts in the summer, water fills these cracks, and they freeze creating wedges. The process repeats itself increasing the size of the wedges and changing the landscape. These dynamic features, which include pingos, ice wedges, polygons, and tussucks, can slowly change year to year. The tundra photos below are some examples of these features.
Polygons and Ice Wedges
Polygons are formed as a result of the freeze and thaw cycle. When soil contracts in the deep cold, cracks form. During spring snowmelt and summer rains, water flows into the crack and is trapped and frozen by surrounding permafrost. Freezing water expands and forces the surrounding soil upward and outward.
Ponds and Thermokarsts (surface depressions)
When permafrost melts, the land slumps and fills the void, creating a surface depression or thermokarst. These thermokarsts may take on a variety of shapes.
The word “pingo” comes from an Inupiaq name for a cone-shaped hill or mound of soil with a core of ice. An average pingo is about 100 feet (30 meters) high and 1650 feet (50 meters) in diameter. Pingos can occur in areas of both continuous and discontinuous permafrost.
Meandering Streams and Rivers
Solifluction Lobes or Gelifluction
Because water can’t seep into the frozen underlayer of permafrost, the active layer of topsoil gets water-saturated. The weight of the soil causes the active layer to slide, or slump, downhill when thawed in summer. The rate of movement depends on the slope and amount of vegetative cover. Movement can vary from a fraction of an inch per year to an avalanche rush.
Permafrost Ice Lens
Plants of the Tundra
The plants that survive in the active topsoil layer of the tundra have developed unique adaptations to endure a long and cold winter. Tree growth is absent or limited because of the shallow active layer. Depending on the degree of wetness, different plants dominate the tundra. In wet areas cotton grass and sedges are common and in the dryer areas, grasses, flowers, dwarf willows and many flowers grow quickly under a short summer.
Dwarf birch and black spruce
Alaska Cotton Grass
Animals of the tundra
Not many animals live year round in the tundra. To avoid the harsh conditions of winter, animals either migrate, hibernate, or have body insulation adaptations to withstand the super cold.
Arctic Ground Squirrel
Barren Ground Caribou
Birds of the Tundra
The tundra wetlands areas can be extremely productive under the brief summer, which draws many migratory birds and waterfowl to feed and raise their young.