The interdependence of climate, permafrost, soils, plants, animals and people.
Biodiversity - The variety of life in the world or a particular habitat.
Fragile environment - An environment that is both easily disturbed and difficult to restore if disturbed. Plant communities in fragile areas have evolved in highly specialised ways to deal with challenging conditions. As a result, they cannot tolerate environmental changes.
Tundra and other cold environments are incredibly fragile wilderness environments where people can generally only live in low densities. The plants, animals and people that live in these environments are incredibly INTERDEPENDENT upon each other and on the delicate balance for life offered by the harsh climate, the permafrost and the soils. Many indigenous people have had to inhabit slightly warmer coastal areas where the fish and hunt for fish, whales and even sharks for food and blubber and oils. The Vuntut Gwitchin have established themselves along the migration route of the Porcupine Caribou herd, and they take only sustainable numbers during their hunting period.
Many of the animals are migratory, whilst many tundra birds use the moss to line their nests against fiercely cold Arctic winds. There are clear links between the abiotic and biotic factors within the tundra ecosystem. The plants, animals and people are linked together in a food web, as shown below.
An example of a Tundra Food web
Issues related to biodiversity.
Biodiversity, the amount and variety of life in this tundra environment, is low because;
1. The temperatures and precipitation in these tundra areas are both LOW, and these abiotic factors mean that this is a very difficult environment for life to survive, as there is minimal water and sunlight available for survival.
2. The cold temperatures and low precipitation also mean that decomposition only happens slowly so very little organic matter is added to the soil each year. This means that the soils are generally thin and infertile, allowing only hardy low lying plants like moss to survive
3. The soil is also frozen for part of the year and waterlogged when the soil melts in summer, again not ideal for plant growth
4. Snow cover in winter reduces the chance for plant growth further
5. In winter there is permanent darkness for many months in these northerly latitudes, plants and animals have to adapt to these harsh conditions.
As a result of this low biodiversity, the tundra ecosystem is very fragile. Any small changes in the ecosystem can have very big impacts on the food web. If producers such as moss were damaged by disease or human activity, the animals in this area would suffer greatly as food sources of plants are already in short supply because of the harsh conditions. Biodiversity does increase in summer when conditions are better and migratory animals and birds arrive to take advantage of this. The photograph opposite shows the Tundra in Siberia, note the large amounts of standing water, the lack of trees and the low-lying nature of the plants.
Tundra in Siberia by Dr. Andreas Hugentobler (Own work), via Wikimedia Commons
How plants and animals adapt to the physical conditions.
The cold, brisk winds, very short growing seasons, waterlogged and seasonally frozen soils all pose challenges for the plants and animals living in the Tundra. They must therefore be able to adapt to extreme and the rather harsh conditions found in this Biome. They have to have special adaptations to allow them to live in extreme conditions and low temperatures.
Plant Adaptations in the Tundra Biome
Plants in the Tundra have adapted in a variety of ways;
There are 2 types of Arctic Moss, one is an aquatic plant found growing on the bottom of tundra lake beds and in and around bogs and fens. Because it can grow under water it is protected from the drying winds and cold, dry air of the frozen tundra. The Arctic Moss has adapted well to its cold climate. They are short and never have wooden stems and have tiny leaves, usually only one cell thick. Their short nature means that it is adapted to the incredibly strong winds because it grows near to the ground. There are lots of leaves on the stem and they do not have flowers. The more leaves the more they can photosynthesize which is an advantage in this cold climate with short growing season.
They can either reproduce by growing shoots or by sending out spores, which need to be wet to survive. It is very slow growing. It grows as slow as one centimetre per year. When it is not growing, it stores nutrients so new leaves can be made quickly next spring. It also lives a very long time; the shoots live seven to nine years, the leaves live for four. Its long life and slow growth are probably adaptations to the short growing season and the cold.
Arctic Moss - By Jason Hollinger via Wikimedia Commons
Animal Adaptations in the Tundra Biome
Animals have many adaptations to survive in this harsh environment;
Caribou are a good example of an Arctic animal that has adapted to its environment. For example, they have 2 layers of fur to help them with the cold. They also have the behavioural adaptation of migrating to escape the worst of the winter cold. The Caribou have a body that helps too, they have a compact, stocky body with a short tail and ears to avoid losing body heat. Their legs even have veins and arteries that run side by side, so that the heat of the arterial blood coming from the body warms the cooler venous blood returning from the lower legs.
For feet, Caribou also have split-hooves, like a cow. They walk on the middle two toes of each foot, which are covered with hooves. Because there are two hooves instead of one as in the horse, they can spread apart to bear more weight without sinking into snow or wet ground, and also act as paddles when swimming.
Even the caribou's digestion has adapted to their environment. During the summer they browse and graze like other plant-eaters, but come winter, they eat lichen. Caribou can smell lichen under deep snow and use their scoop-shaped hooves to dig down to it. They also have developed special bacteria in their gut that help them digest lichen, and their ability to use this abundant but low-nutrition food helps them survive when there is nothing else to eat.