Tundra

Tundra Biome

              In the very cold places of the world, survival isn't easy. The soil is frozen, its top surface thawing only during summer, and no trees can grow. Yet plants and animals that are adapted for the harsh conditions thrive. This biome is called tundra. Most of the world's tundra is found in the north polar region. It is called Arctic tundra. There is a small amount of tundra on parts of Antarctica that are not covered with ice. Plus, tundra is found on high altitude mountains and is called alpine tundra.

             Permafrost is the term given to frozen soil. During the winter months, permafrost reaches the surface of the tundra. It is very cold during the winter, with temperatures reaching -60 degrees Fahrenheit (-51 degrees Celsius). Very few animals are active in these harsh conditions.

              In the summer time, the tundra changes. The Sun is out almost 24 hours a day, so the tundra starts to warm up. The permafrost melts at the surface, and plant life grows. However, the permafrost only disappears for a few inches below the surface. There isn't enough soil for trees to grow, so only small plants are found in the tundra.

          At the same time, a variety of animals come out to feast on the plants. Insects come to feed on the animals, and birds appear to enjoy the insects.

Characteristics of tundra include:

1. Extremely cold climate


2. Low biotic diversity


3. Simple vegetation structure


4. Limitation of drainage


5. Short season of growth and reproduction


6. Energy and nutrients in the form of dead organic material


7. Large population oscillations

Tundra is separated into two types:

Arctic tundra

                    Arctic tundra is located in the northern hemisphere, encircling the north pole and extending south to the coniferous forests of the taiga. The arctic is known for its cold, desert-like conditions. The growing season ranges from 50 to 60 days. The average winter temperature is -34° C (-30° F), but the average summer temperature is 3-12° C (37-54° F) which enables this biome to sustain life. Rainfall may vary in different regions of the arctic. Yearly precipitation, including melting snow, is 15 to 25 cm (6 to 10 inches). Soil is formed slowly. A layer of permanently frozen subsoil called permafrost exists, consisting mostly of gravel and finer material. When water saturates the upper surface, bogs and ponds may form, providing moisture for plants. There are no deep root systems in the vegetation of the arctic tundra, however, there are still a wide variety of plants that are able to resist the cold climate. There are about 1,700 kinds of plants in the arctic and subarctic, and these include:

• low shrubs, sedges, reindeer mosses, liverworts, and grasses


• 400 varieties of flowers


• crustose and folios lichen

                   All of the plants are adapted to sweeping winds and disturbances of the soil. Plants are short and group together to resist the cold temperatures and are protected by the snow during the winter. They can carry out photosynthesis at low temperatures and low light intensities. The growing seasons are short and most plants reproduce by budding and division rather than sexually by flowering. The fauna in the arctic is also diverse:

• Herbivorous mammals: lemmings, voles, caribou


• Carnivorous mammals: arctic foxes, wolves, and polar bears


• Migratory birds: ravens, snow buntings, falcons, loons,


• Insects: mosquitoes, flies, moths, grasshoppers


• Fish: cod, flatfish, salmon, and trout

                  Animals are adapted to handle long, cold winters and to breed and raise young quickly in the summer. Animals such as mammals and birds also have additional insulation from fat. Many animals hibernate during the winter because food is not abundant. Another alternative is to migrate south in the winter, like birds do. Reptiles and amphibians are few or absent because of the extremely cold temperatures. Because of constant immigration and emigration, the population continually oscillates.

Alpine tundra
   
                           Alpine tundra is located on mountains throughout the world at high altitude where trees cannot grow. The growing season is approximately 180 days. The nighttime temperature is usually below freezing. Unlike the arctic tundra, the soil in the alpine is well drained. The plants are very similar to those of the arctic ones and include:

• tussock grasses, dwarf trees, small-leafed shrubs, and heaths

Animals living in the alpine tundra are also well adapted:

• Mammals: pikas,, mountain goats, sheep


• Birds: grouse like birds


• Insects: spring tails, grasshoppers ,beetles

world biomes

Our ecosystem

        Introduction - What is an Ecosystem?

              An ecosystem consists of the biological community that occurs in some locale, and the physical and chemical factors that make up its non-living or abiotic environment. There are many examples of ecosystems -- a pond, a forest, an estuary, a grassland. The boundaries are not fixed in any objective way, although sometimes they seem obvious, as with the shoreline of a small pond. Usually the boundaries of an ecosystem are chosen for practical reasons having to do with the goals of the particular study.

                

       The study of ecosystems mainly consists of the study of certain processes that link the living, or biotic, components to the non-living, or abiotic, components. Energy transformations and bio geochemical cycling are the main processes that comprise the field of ecosystem ecology. As we learned earlier, ecology generally is defined as the interactions of organisms with one another and with the environment in which they occur. We can study ecology at the level of the individual, the population, the community, and the ecosystem.

      

          Studies of individuals are concerned mostly about physiology, reproduction, development or behavior, and studies of populations usually focus on the habitat and resource needs of individual species, their group behaviors, population growth, and what limits their abundance or causes extinction. Studies of communities examine how populations of many species interact with one another, such as predators and their prey, or competitors that share common needs or resources.

           

          In ecosystem ecology we put all of this together and, insofar as we can, we try to understand how the system operates as a whole. This means that, rather than worrying mainly about particular species, we try to focus on major functional aspects of the system. These functional aspects include such things as the amount of energy that is produced by photosynthesis, how energy or materials flow along the many steps in a food chain, or what controls the rate of decomposition of materials or the rate at which nutrients are recycled in the system. 

Structure of an Ecosystem

             

            An ecosystem is the basic functional unit in ecology, as it includes both organisms and their abiotic environment. No organism can exist without the environment. Ecosystem represents the highest level of ecological integration which is energy based. A pond, a lake, a coral reef, part of any field and a laboratory culture can be some of the examples of ecosystems. Thus an ecosystem is defined as a specific unit of all the organisms occupying a given area which interacts with the physical environment producing distinct trophic structure, biotic diversity and material cycling.

Major ecosystems: 

• Savannah ecosystem
• Desert ecosystem
• Grassland ecosystem
• Aquatic ecosystem
• Forest ecosystem 

  Major biomes                            

Desert ecosystem

Desert Ecosystem


              Though a desert may seem like a barren land devoid of lifeforms, life does exist in this harsh environment. Numerous plants and animal species have adapted to these seemingly unsuitable conditions. In the desert ecosystem, climate is a deciding factor for the existence of lifeforms. In deserts, temperatures can reach up to 115° F during the day, and come down to 32° F at night. Such extreme temperature makes it difficult for lifeforms to survive in the deserts, unless they adapt to this harsh climate. Surprisingly though, many plants and animals have adapted themselves over the years, and have become an important part of the desert ecosystem today.

Definition: Desert Ecosystem
 
                In geographical studies, deserts are defined as regions wherein the average annual precipitation seldom exceeds more than 10 inches per year, and the amount of water lost to evapotranspiration is much more than the amount of water gained by precipitation. Like hot deserts, such as the Sahara and Mojave, there are cold deserts as well, the best example being Antarctica. One of the prominent difference between the two is the form of precipitation, which is snowfall in cold deserts and rainfall in hot deserts. Irrespective of whether it is a hot or a cold desert, the characteristic traits of both almost remain the same. It may comes as a surprise, but the areas which we refer to as hot deserts have a chilling temperature at night.

Desert Ecosystem: Animals
 
              Not many of us are aware of the fact that deserts are home to a number of species of kingdom Animalia. Biodiversity of the deserts is as unique as other biomes of the world. You might not see these animals as you see zebras and wildebeests in Africa, but they do exist and each of these species play a crucial role in the desert ecosystem food chain. Like in most of the other ecosystems, plants are the primary producers, while rodents, insects and reptiles which feed on these plants are the primary consumers. Then come the secondary consumers, who mainly comprise larger reptiles and insects which feed on primary consumers. At the top of the desert food chain are the apex predators in the form of birds and mammals. Most prominent members of the desert animals list include the Gila monster, chuckawallas, desert tortoise, rattlesnakes, hawks, ostriches, bobcat, kangaroo rats, mountain lions, etc. Most of these desert animals are nocturnal, i.e. active during the night, and spend the entire day burrowing. This adaptation helps them to fight the soaring temperatures that persist during the day. Water being scarce in deserts, these animals have also modified themselves to make the most of the available water. Some animals absorb water from plants, while others store it in their fatty tissues. Read more on adaptations in desert animals.

Desert Ecosystem: Plants
 

              When we talk about desert vegetation, most of us only think about cactus. However, we fail to understand that within cactus, there are different types which grow in different deserts of the world. These plants have have modified themselves to sustain in the desert environment. Some plants store water in the specialized tissues, while others have small leaves with hair like structures which reduce the evaporation of moisture. In North American deserts, barrel cactus is the most abundantly found cacti species, while other species include crimson hedgehog cactus, pancake prickly pear cactus, saguaro cactus, etc. Other cactus plants such as brittle bush, saltbush, creosote bush, desert ironwood, gravillias, Joshua tree, Mojave aster, Soaptree yucca, hanging chain cholla, etc., are also quite common in deserts. Read more on desert plant life.

Our ecosystem