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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.

A fundamental classification of biomes is into: Terrestrial (land) biomes Freshwater biomes Marine biomes

Biomes are climatically and geographically defined areas of ecologically similar climatic conditions such as communities of plants, animals, and soil organisms,[1] and are often referred to as ecosystems. Biomes are defined by factors such as plant structures (such as trees, shrubs, and grasses), leaf types (such as broadleaf and needleleaf), plant spacing (forest, woodland, savanna), and climate. Unlike ecozones, biomes are not defined by genetic, taxonomic, or historical similarities. Biomes are often identified with particular patterns of ecological succession and climax vegetation (quasi-equilibrium state of the local ecosystem). An ecosystem has many biotopes and a biome is a major habitat type. A major habitat type, however, is a compromise, as it has an intrinsic inhomogeneity. The biodiversity characteristic of each biome, especially the diversity of fauna and subdominant plant forms, is a function of abiotic factors and the biomass productivity of the dominant vegetation. In terrestrial biomes, species diversity tends to correlate positively with net primary productivity, moisture availability, and temperature.[2]

In 2006, the number of endangered species rose to more than 16,000 worldwide. Habitat loss, pollution and human-animal conflict all play a part when species are threatened with extinction. Introductions of non-native species devastate local native populations and alter ecosystems. From elephants, leopards and bears to monk seals, sea turtles, manatees and whales we'll explore wildlife conservation issues and find some reasons to be encouraged. With new species being discovered every day, interest in protecting some of the world's unique habitats is growing.

tropical rainforests are considered a type of tropical wet forest (or tropical moist broadleaf forest) and may also be referred to as lowland equatorial evergreen rainforest

and may also be referred to as lowland equatorial evergreen rainforest

Rainforests are home to half of all the living animal and plant species on the planet.[2] Tropical rain forests are called the "world's largest pharmacy" because over one-quarter of modern medicines originate from its plants.

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.

Many species of animal life can be found in the rain forest. Common characteristics found among mammals and birds (and reptiles and amphibians, too) include adaptations to a life in the trees, such as the prehensile tails of New World monkeys. Other characteristics are bright colors and sharp patterns, loud vocalizations, and diets heavy on fruits. Insects make up the largest single group of animals that live in tropical forests. They include brightly colored butterflies, mosquitoes, camouflaged stick insects, and huge colonies of ants. The Amazon river basin rainforest contains a wider variety of plant and animal life than any other biome in the world. The second largest population of plant and animal life can be found in scattered locations and islands of Southeast Asia. The lowest variety can be found in Africa. There may be 40 to 100 different species in 2.5 acres ( 1 hectare) of a tropical rain forest.   When early explorers first discovered the rainforests of Africa, Southeast Asia and South America, they They were amazed by the dense growth, trees with giant buttresses, vines and epiphytes . The tropical vegetation grew so dense that it was difficult to cut one's way through it. It was thought at the time that the soil of a rainforest must be very fertile, filled with nutrients, enabling it to support the immense trees and other vegetation they found. Today we know that the soil of the tropical rainforests is shallow, very poor in nutrients and almost without soluble minerals. Thousands of years of heavy rains have washed away the nutrients in the soil obtained from weathered rocks. The rainforest has a very short nutrient cycle. Nutrients generally stay in an ecosystem by being recycled and in a rainforest are mainly found in the living plants and the layers of decomposing leaf litter. Various species of decomposers like insects, bacteria, and fungi make quick work of turning dead plant and animal matter into nutrients. Plants take up these nutrients the moment they are released. A study in the Amazon rainforest found that 99% of nutrients are held in root mats. When a rainforest is burned or cut down the nutrients are removed from the ecosystem. The soil can only be used for a very short time before it becomes completely depleted of all nutrients.

Besides these four layers, a shrub/sapling layer receives about 3 % of the light that filters in through the canopies. These stunted trees are capable of a sudden growth surge when a gap in the canopy opens above them. The air beneath the lower canopy is almost always humid. The trees themselves give off water through the pores (stomata) of their leaves. This process, called transpiration, can account for as much as half of the precipitation in the rain forest. Rainforest plants have made many adaptations to their environment. With over 80 inches of rain per year, plants have made adaptations that helps them shed water off their leaves quickly so the branches don't get weighed down and break. Many plants have drip tips and grooved leaves, and some leaves have oily coatings to shed water. To absorb as much sunlight as possible on the dark understory, leaves are very large. Some trees have leaf stalks that turn with the movement of the sun so they always absorb the maximum amount of light. Leaves in the upper canopy are dark green, small and leathery to reduce water loss in the strong sunlight. Some trees will grow large leaves at the lower canopy level and small leaves in the upper canopy. Other plants grow in the upper canopy on larger trees to get sunlight. These are the epiphytes such as orchids and bromeliads. Many trees have buttress and stilt roots for extra support in the shallow, wet soil of the rainforests. Over 2,500 species of vines grow in the rainforest. Lianas start off as small shrubs that grow on the forest floor. To reach the sunlight in the upper canopy it sends out tendrils to grab sapling trees. The liana and the tree grow towards the canopy together. The vines grow from one tree to another and make up 40% of the canopy leaves. The rattan vine has spikes on the underside of its leaves that point backwards to grab onto sapling trees. Other "strangler" vines will use trees as support and grow thicker and thicker as they reach the canopy, strangling its host tree. They look like trees whose centers have been hollowed out. Dominant species do not exist in tropical rainforests. Lowland dipterocarp forest can consist of many different species of Dipterocarpaceae, but not all of the same species. Trees of the same species are very seldom found growing close together. This bio diversity and separation of the species prevents mass contamination and die-off from disease or insect infestation. Bio diversity also insures that there will be enough pollinators to take care of each species' needs. Animals depend on the staggered blooming and fruiting of rainforest plants to supply them with a year-round source of food.

There are four very distinct layers of trees in a tropical rain forest. These layers have been identified as the emergent, upper canopy, understory, and forest floor. Emergent trees are spaced wide apart, and are 100 to 240 feet tall with umbrella-shaped canopies that grow above the forest. Because emergent trees are exposed to drying winds, they tend to have small, pointed leaves. Some species lose their leaves during the brief dry season in monsoon rainforests. These giant trees have straight, smooth trunks with few branches. Their root system is very shallow, and to support their size they grow buttresses that can spread out to a distance of 30 feet. The upper canopy of 60 to 130 foot trees allows light to be easily available at the top of this layer, but greatly reduced any light below it. Most of the rainforest's animals live in the upper canopy. There is so much food available at this level that some animals never go down to the forest floor. The leaves have "drip spouts" that allows rain to run off. This keeps them dry and prevents mold and mildew from forming in the humid environment. The understory, or lower canopy, consists of 60 foot trees. This layer is made up of the trunks of canopy trees, shrubs, plants and small trees. There is little air movement. As a result the humidity is constantly high. This level is in constant shade. The forest floor is usually completely shaded, except where a canopy tree has fallen and created an opening. Most areas of the forest floor receive so little light that few bushes or herbs can grow there. As a result, a person can easily walk through most parts of a tropical rain forest. Less than 1 % of the light that strikes the top of the forest penetrates to the forest floor. The top soil is very thin and of poor quality. A lot of litter falls to the ground where it is quickly broken down by decomposers like termites, earthworms and fungi. The heat and humidity further help to break down the litter. This organic matter is then just as quickly absorbed by the trees' shallow roots

Scientists believe that there is such a great diversity of animals because rainforests are the oldest ecosystem on earth.

Many animals species have developed relationships with each other that benefit both species. Birds and mammal species love to eat the tasty fruits provided by trees. Even fish living in the Amazon River rely on fruits dropped from forest trees. In turn, the fruit trees depend upon these animals to eat their fruit, which helps them to spread their seeds to far-off parts of the forest.

Tropical rainforests are the most diverse ecosystems on earth. A four-square mile patch of rainforest contains as many as 1500 species of flowering plants, 750 species of trees, 125 species of mammals, 400 species of birds, 100 species of reptiles, 60 species of amphibians, and 150 species of butterflies. More than 50% of the world's plant and animal species inhabit the 7% of the world that is covered in rainforest.

Some forests in Southeast Asia have been around for more than 100 million years, when the dinosaurs roamed the Earth. During the Ice Ages, the last of which occurred about 10,000 years ago, the frozen areas of the North and South Poles spread over much of the earth, causing huge numbers of extinctions.

While there are many species of plants in a square-mile of tropical rainforest, there may only be one or two of each. In addition as most of the species are found nowhere else on Earth, by removing one plant or animal, the fragile ecosystem would be threatened, and the species may be forced into extinction.

A food chain is the sequence of who eats whom in a biological community (an ecosystem) to obtain nutrition. A network of many food chains is called a food web. The food chain starts with plants or other autotrophs (organisms that make their own food from light and/or chemical energy) - these organisms are called primary producers. The primary producers are eaten by herbivores (plant-eaters) called primary consumers. The herbivores are eaten by carnivores (meat-eaters) and omnivores (animals that eat both animals and plants) - these organisms are called secondary consumers. Secondary consumers may be eaten by other carnivores called tertiary consumers. When any organism dies, it is eaten by tiny microbes (detrivores) and the exchange of energy continues.

A food chain is the sequence of who eats whom in a biological community (an ecosystem) to obtain nutrition. A network of many food chains is called a food web. The chain starts with plants or other autotrophs (organisms that make their own food from light and/or chemical energy) that are eaten by herbivores (plant-eaters). The herbivores are eaten by carnivores (meat-eaters). These are eaten by other carnivores. When any organism dies, it is eaten by tiny microbes (detrivores) and the exchange of energy continues.

These ecosystems are either barren or with scanty vegetation consisting of mainly thorny bushes. Deserts are classified as warm (hot) and cold (temperate) deserts. The hot deserts are the Sahara in Northern Africa, Kalahari in Southern Africa, Thar in India, Atacama in South America, deserts of Mexico and Australia.The deserts of Iran and Turkey, Gobi desert of Mongolia, some deserts of Argentina are recognised as temperate or cold deserts. Characteristics of Desertsi) Most deserts receive some rain every year but not uniform. ii) Light green covering of annuals is seen just after rains.iii) Have scanty vegetation, clear skies, hot days and extremely cold nights. iv) Soil is rocky and encrusted with sand or salt.v) Long periods without precipitation and extreme temperature (50 - 60oC) conditions (arid lands) impose considerable restraints on the flora and fauna which inhabit there. vi) Sandy storms are very frequent.vii) Occur generally in rain shadow areas. Flora1) Includes succulents such as Cacti and Euphorbias, which can store water in their tissues. 2) Trees with long spreading roots such as Acacia, Prosopis, Phoenix (dates) are found.3) Ephemerals (short lived) such as Boerhaavia repens are seen only during rainy season. FaunaMost desert animals are nocturnal and avoid the heat of the day by burrowing into the cooler soil. Animals include ants, locusts, lizards, Gila monster, coral snake, rattle snake, burrowing owls, Gambel's quail, kangaroo rats, rabbits, camel, skunk, badger foxes, jackals and desert cats. In general, the organisms having specialised structural and physiological and behavioural adaptations to withstand the extreme temperatures only can survive in a desert.

The largest of all the ecosystems, oceans are very large bodies of water that dominate the Earth's surface. Like ponds and lakes, the ocean regions are separated into separate zones: intertidal, pelagic, abyssal, and benthic. All four zones have a great diversity of species. Some say that the ocean contains the richest diversity of species even though it contains fewer species than there are on land.

A biome is a large geographical area of distinctive plant and animal groups, which are adapted to that particular environment. The climate and geography of a region determines what type of biome can exist in that region. Major biomes include deserts, forests, grasslands, tundra, and several types of aquatic environments. Each biome consists of many ecosystems whose communities have adapted to the small differences in climate and the environment inside the biome. All living things are closely related to their environment. Any change in one part of an environment, like an increase or decrease of a species of animal or plant, causes a ripple effect of change in through other parts of the environment. The earth includes a huge variety of living things, from complex plants and animals to very simple, one-celled organisms. But large or small, simple or complex, no organism lives alone. Each depends in some way on other living and nonliving things in its surroundings.