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Deserts take up about one third (33 percent) of the Earth's land surface.

Deserts are often composed of sand and rocky surfaces.

In hot deserts the temperature in the daytime can reach 45 °C/113 °F or higher in the summer, and dip to 0 °C/32°F or lower in the winter.

Biomes are defined as "the world's major communities, classified according to the predominant vegetation and characterized by adaptations of organisms to that particular environment" (Campbell 1996).

It is estimated that nearly half of the world's estimated 10 million species of plants, animals, and microorganisms will be destroyed or severely threatened over the next quarter-century due to rainforest deforestation.

Commercial logging is the single largest cause of rainforest destruction, both directly and indirectly. Other activities destroying the rainforest, including clearing land for grazing animals and subsistence farming. The simple fact is that people are destroying the Amazon rainforest and the rest of the rainforests of the world because "they can't see the forest for the trees."

When a medicine man dies without passing his arts on to the next generation, the tribe and the world loses thousands of years of irreplaceable knowledge about medicinal plants.

What is a Biome?     A biome is a large area with similar flora, fauna, and microorganisms.  Most of us are familiar with the tropical rainforests, tundra in the arctic regions, and the evergreen trees in the coniferous forests. Each of these large communities contain species that are adapted to its varying conditions of water, heat, and soil.  For instance, polar bears thrive in the arctic while cactus plants have a thick skin to help preserve water in the hot desert.  To learn more about each of the major biomes, click on the appropriate heading to the right.  What is an Ecosystem?     Most of us are confused when it comes to the words ecosystem and biome.  What's the difference?  There is a slight difference between the two words.  An ecosystem is much smaller than a biome.  Conversely, a biome can be thought of many similar ecosystems throughout the world grouped together.  An ecosystem can be as large as the Sahara Desert, or as small as a puddle or vernal pool.     Ecosystems are dynamic interactions between plants, animals, and microorganisms and their environment working together as a functional unit.  Ecosystems will fail if they do not remain in balance.  No community can carry more organisms than its food, water, and shelter can accomodate.  Food and territory are often balanced by natural phenomena such as fire, disease, and the number of predators.  Each organism has its own niche, or role, to play.

The four major types of biomes are aquatic, grasslands, forests, and desert. Aquatic biomes are probably the most important of all the biomes. Their medium, water, is a major natural resource. Aquatic biomes can be subdivided into freshwater, seawater and atmospheric biomes. Grasslands can be subdivided into savanna, temperate grasslands (prairie) and tundra. This classification corresponds to decreasing average temperatures. Forests receive more precipitation than other biomes and vary from boreal, to temperate, to rainforest. This classification corresponds to increasing temperatures. Deserts have the fewest species and the most extreme climate

The taiga or coniferous forest is probably the world's largest land biome. It is located south of the tundra and stretches across portions of North America. Europe and Asia. During the summers, the soil remains very wet and is suitable for lichens and mosses. Fir and spruce trees grow well in this environment. The trees provide homes for many birds including the crossbill, which is capable of cracking cones to eat the seeds. A variety of animals are found in the taiga. They include moose, weasels. wolves, deer. Lynx, caribou, porcupines, beaver, mink and bears.

Infectious diseases unwittingly brought by the Europeans or transferred from the Bantus are taking their toll amongst the pygmies: in a typical community about 20% of the population is ill. They suffer particularly from malaria, eye diseases such as endemic river-blindness, intestinal worm diseases, framboesia, lung- and viral infections and from wounds which easily go septic in this tropical environment. Many children catch measles and suffer from polio and their mortality rate is very high. Adequate health care is expensive and local resources are extremely limited. The unique pygmy people need our support. With the help of the many friends of the pygmies around the globe we provide essential health-care and assistance in education and agriculture - but with more funds we could do so much more. A little money goes a very long way. For example, for only Euro 30, -- you can send a pygmy child to school for a whole year. We can pay the teacher and provide educational materials and medical care for the pupil. We need your support

Pygmies - page 2

Deserts are defined by how much rain they get. Most deserts, like the Sonoran in North America and Sahara in Africa, are hot. They receive less than 25cm of rain each year. The South and North Poles are also deserts but very cold.

Today, we know that the soil of the tropical rainforests is thin and very low in nutrients. Decomposers like leaf-cutter ants, termites, bacteria, and fungi quickly turn falling leaves and dead organisms into nutrients. Plants take up these nutrients the moment they are available, so they don’t get a chance to enrich the soil. Keeping Tropical Rainforests Healthy Conservation of tropical rainforests should be easy. They have survived for millions of years. The trick to keeping them healthy is to not take too much too fast. This gives the rainforests time to recover from human activities like logging. But many countries that have tropical rainforests are poor. They can make money by cutting down and developing the rainforests. But uncontrolled development results in deforestation

Rainforests have 170,000 of the world's 400,000 known plant species. The United States has 81 species of frogs, while Madagascar (which is smaller than Texas) may have 300 species. Europe has 321 butterfly species, while Manu National Park in the tropical rainforest of Peru has 1,300 species! The world’s only species of flying snake and lizard live in the Borneo rainforest. The largest catfish in the world lives in a tropical rainforest river in Vietnam. It weighs over 300 kg. About one-quarter of all the medicines we use come from rainforest plants. Curare comes from a tropical vine. It is used as an anesthetic and to relax muscles during heart surgery. Quinine, from the cinchona tree, is used to treat malaria. A person with leukemia has a 99% chance that the disease will go into remission because of the rosy periwinkle. More than 1,400 varieties of tropical plants might be potential cures for cancer.

Some traditional rainforest cultures still live in the forests. They travel as a group to collect and hunt food. As rainforests are destroyed, so are the homes of these interesting and amazing people.

Some humans benefit from decreasing the size of the rainforest - people who use the electricity caused by a hydro-electric dam, for example. Other humans do not have it so good - people who hunt wildlife for a living may a tougher time finding food. The loss of indigenous culture is kind of sad. Read Tristes Tropique by the anthropologist Claude Levi Strauss to learn more about people who are hurt by the loss of forest. "Under developing the Amazon" by Stephen Bunker is a good look at the costs and benefits, who gains and who loses from the destruction/development of the rainforests.

Mojave National PreserveWorld Deserts World Deserts North American Deserts Protecting Deserts Home Desert lands cover incredible distances. Many who have driven through deserts in the United States may think they are enormous, but they are only the fifth largest in the world covering about 500,000 square miles. By contrast the great Sahara Desert covers almost 3.5 million square miles, the Australian deserts 1.3 million square miles, the Arabian deserts 1 million square miles, while the deserts of Turkestan have 750,000 square miles. Numerous smaller deserts are also scattered across the globe. All are unique, and have adapted to their own particular environments. Global Weather PatternsDeserts tend to occur in two belts that circle the globe. Both the Northern and Southern Hemisphere have this belt located between 15 and 35 degrees latitude, roughly centered over the Tropic of Cancer and the Tropic of Capricorn. This is no accident. The sun is more directly overhead the equatorial region so it receives the most intense sunlight, and this solar energy heats the air. Hot air has two important qualities: it can hold enormous quantities of moisture, and it rises up into the atmosphere. So hot tropical air tends to be moist and rise into the atmosphere. As this air rises it cools, condensing the moisture and converting it to water where it falls as rain. This is why rain forests tend to occur near the equator. What goes up must come down, and gravity pulls this mass of rising air back to the ground. Tropical air typically falls at about 30 degrees latitude on either side of the equator and along the desert belt, but robbed of its moisture it is now hot and dry. The result are often persistent high pressure systems that tend to block incoming storms, or push them into other regions. These patterns make deserts possible, but typically other factor must also intrude to make deserts a reality.

There are about 1,000 indigenous tribes in the rainforests of the world.

Those nearest the equator, where the climate is very hot and wet all through the year, are evergreen because the trees can grow all the time and so are always in leaf

Cloud forests are yet another type of rainforest, so-called because they can be found high up mountains, where they are nearly always in cloud. The climate here is very cool but extremely wet.

A Food Pyramid in the Hot Desert Biome      Here we see a food pyramid that shows how the Kilocalories pass up the food chain.      The first trophic level is occupied by the primary producers, which are the plants.  Plants make food through photosynthesis. The limiting factor for these plants is the shortage of water, so they produce fewer than 200 Kilocalories of food for the animals for each square meter each year.     The primary consumers, who eat the plants, occupy the second trophic level. These animals have very little to eat, and are small. Many are insects, or reptiles, who are cold blooded and who use less energy to maintain their bodies than mammals and birds do. As food for predators, they provide about 20 Kilocalories per square meter per year for predators.      The predators are the secondary consumers. They occupy the third trophic level. Again we see cold-blooded animals, such as snakes, insect-eating lizards, and tarantualas. Only about 2 Kilocalories per square meter per year are stored in their bodies. In the harsher desert environments, they are the top predators.     In areas where deserts get more rain, more plant material is produced and a few tertiary consumers may be able to survive. They form a fourth trophic level.      This diagram shows the energy available at each trophic level in the hot desert biome. These numbers tell about the numbers of Kilocalories per square meter per year.  Cold Desert Energy Pyramid  Introduction to Desert Biomes  Return to Introduction to Biomes © Elizabeth Anne Viau, 1999. This material may be used freely for instructional purposes but not sold for a price beyond the cost of reproduction. Please inform the author if you use it at eviau@earthlink.net

Animals of the rain forests are provided with a variety of habitats in the different layers of the forest trees. Some live at the top of the tallest trees while others live in the lower zones. Some animals, live on the ground level or even below the surface and so we have this vast and complex pattern of plant and animal life which has been evolving steadily for millions of years.

Animals of the rain forests are provided with a variety of habitats in the different layers of the forest trees. Some live at the top of the tallest trees while others live in the lower zones. Some animals, live on the ground level or even below the surface and so we have this vast and complex pattern of plant and animal life which has been evolving steadily for millions of years.

Fish is the common name for 29,000 species of cold-blooded, backboned animals that live in freshwater and ocean environments. Fish breathe using gills. Most have a body covering of scales and move using fins. Many fish hunt other fish for food. Fish are also an important food for other animals such as humans, birds, seals, and whales. Overfishing by humans has now made some fish endangered.

NTERDEPENDENCE - In all environments, various plants and animals depend on each other either directly or indirectly for survival.

Author: barry a bieda How does the cutting of the rainforest affect Earth? Response #: 1 of 1 Author: mortis Well, we have been cutting rainforests for thousands of years with no permanent damage to the earth at all. Forest people who cut small patches for growing gardens do not hurt the forest because the small plots recover their original growth very quickly: think of the pictures of Mayan ruins in Mexico that are completely covered by forest - these used to be open, active cities! So on a small scale, slash and burn agriculture has no effect whatever on the rain-forest- it is a sustainable use of the forest. However, on a large commercial scale, where bulldozers and flame-throwers are use to convert huge tracts of land into pasture for cattle, the ability of the forest to recover is seriously impaired, destroying the forest for a very long time, if not forever. This kind of unsustainable destructive use affects the earth by taking a large portion of the biosphere out of production - which interrupts the carbon and oxygen cycles, affects local water and soil quality, and causes a decline in the global gene pool by making many species extinct.

Ecotourism is environmentally responsible travel to enjoy and appreciate nature and cultural experiences. Ecotourism should have low impact on the environment and should contribute to the well-being of local people.