Ecosystems- This essay covers every major biome in biology, addresses every key term in Enviromental Biology, and gives great illistrations of each biome.

Essay by Dylan18560University, Bachelor'sA+, July 2004

download word file, 24 pages 4.6

Downloaded 301 times

There are several large categories of living communities called biomes. The biomes are made up of ecosystems. The living parts of an ecosystem, like the plants, animals, and bacteria found in soil, are known as a community. The physical surroundings, or biotic components, such as the minerals found in the soil, are known as the environment or habitat.

The major parts of an ecosystem are the producers (green plants), the consumers (herbivores and carnivores), the decomposers (fungi and bacteria), and the nonliving, or abiotic, component, consisting of dead organic matter and nutrients in the soil and water.

I. Estuaries

The Webster's dictionary defines estuaries as "a water passage where the tide meets a river current; an arm of the sea at the lower end of a river." (1)

An estuary is simply a partly-enclosed coastal body of water that a river dumps into an ocean. A delta, or the mouth of the river is essentially the same thing (2).

It has a free connection with the open sea but its salty sea water is diluted with fresh water from inland rivers and creeks. The normally narrow and ribbon-like patterns of estuaries , sand dunes, salt marshes, and flats allows the estuary to act as a "trap" for nutrients washed down towards the sea. This mix of nutrients provides a home to many very different kinds of plants and animals. All of them must be able to adapt to an environment that change by the hour. The ocean tides push salty sea water in and out of estuaries constantly. So this causes water in the morning that may be dry and hot in the afternoon to change to salty in the afternoon, and by nightfall, as ocean water flows out, may return to fresh water as river water rushes in.

In the United States, 40 percent of our rivers and streams are too polluted for swimming and fishing, and 44 percent of U.S. estuaries are degraded. Because of the pollution, states have started to limit the amount of fishing licenses issued to commercial fisheries.

As estuaries become more polluted, the deposit feeders and filter feeders are at risk because the food they eat tends to accumulate chemical pollution. These poisons will accumulate in their bodies and be passed on to shore birds, animals, and humans that eat them. In addition, pollution tends to reduce the amount of light that can penetrate the water. This reduction in light decreases the growth of aquatic plants and limits sea grass to shallower regions, diminishing an important habitat for many species.

Pollutants come in many forms. Many of the estuaries contain polluted sediment. Heavy metals, radioactive waste, and organic chemicals have been introduced intentionally and accidentally. Sometimes is comes as agricultural fertilizers (herbicides and pesticides), and urban runoff (human sewage). It's easy to blame industrial waste, but as much as 25 percent of toxic waste comes from homes (i.e. many cleaners, paints, antifreezes, solvents, and prescription drugs.

Oil is a major problem for open oceans, coastal waters, and estuaries alike. A perfect example of an estuary being ruined was the Exxon Valdez spilled 42 million liters of oil. According to Southern Agency of Environmental Project (3), Canada alone has 300 million liters of motor oil go that goes unrecorded every year. How does this affect an estuary? As the old phrase goes, everything leads to the ocean. Any industrial waste, or residential sewage drains into underground water ways, into rivers, and out to the ocean slowly but eventually. The motor oil being dumped into local sewer drains will eventually lead into an estuary. 300 million liters yearly, is equal to 7 Exxon Valdez oil spills a year.

II. Swamps and Marshes

The biological dictionary defines swamps as "A wetland often partially or intermittently covered with water, one dominated by woody vegetation." (1)

Swamps are forested wetlands, but they are often found near rivers or lakes and have that drains very slowly, therefore is normally saturated with water. They may have water in them for the whole year or for only part of the year. Swamps vary in size and type. Some swamps have soil that is nutrient rich; other swamps have nutrient poor soil. Swamps are often classified by the types of trees that grow in them. Examples are: conifer swamps, hardwood swamps, shrub swamps, cypress swamps. Conifer swamps include trees like white cedar, northern white cedar; eastern hemlock, eastern white pine, pitch pine, loblolly pine, and black spruce. Hardwood swamps possess trees like red maple, black willow, aspen, cottonwood, ashes, elms, swamp white oak, pin oak, tupelo, and birches. Shrub swamps have small trees and bushes like buttonwood, willow, alders and dogwood.

A marsh is characterized by an abundance of reeds, rushes and cattails and is generally treeless and open. The plants grow with their stems partly in and partly out of the water. Marshes can be shallow (6" of water) or deep (2-3' of water). In the deeper marshes, pondweeds and water lilies float on the water. Marshes can be found along streams in poorly drained depressions and also develop in the shallower water along the borders of lakes, ponds and rivers. Florida's Everglades are considered Saw Grass Marshes.

Trees and shrubs are not the only things that reside in swamps or marshes. Marshes host plenty of birds like: American Bittern, Common Yellowthroat, Gadwall, Limpkin, Red-Winged Blackbird, Ruddy Duck, Sora, Swamp Sparrow, and Yellow Rail.

Swamps on the other hand are very specific to which kinds of birds they host in accordance with where the swamp is geographically located. Examples of this are the Northern shrub swamps that host the Barred Owl, Barrow's Golden eye, red-shouldered Hawk, and Wood Duck. In contrast, the Southern Bottomland Hardwood Swamp hosts the Sainson's Warbler, and the Red-bellied Woodpecker. Cypress Swamps also possess woodpeckers, and wood storks, but have a fish diet in comparison with the Hardwood Swamp's: insects, oak, black gum, seeds, nuts, and fruit diet.

Swamps and marshes aren't just a home for birds, insects, trees, and shrubs, but also play a vital role in our community as well. Swamps serve vital roles in flood protection and nutrient removal. The swamps' valuable timber can be continually harvested to provide building materials for people.

Due to the nutrient-rich soils present in swamps, many of these fertile woodlands have been drained and cleared for agriculture and other development. Over 70 percent of the Nation's floodplain forested swamps have been lost.

As a botanist, the biodiversity of a marshland is enormous. Swamps provide valuable habitat for a number or birds. Cypress trees attract fish-eating birds such as the great blue heron, black-crowned night heron, green heron, bitterns, kingfishers, and migrating ospreys. Without the swamps, just think of all the organisms that would go extinct.

III. Tropical Rain Forests

In the Living In The Environment, a tropical rain forest is defined as a broadleaf evergreen forest found near the equator where hot, moisture-laden air rises and dump it's moisture. These forests have a warm annual mean temperature which varies little, a high humidity, heavy rainfall almost daily. (4)

The rain forest is broken down in four main layers. First is the emergent, the tallest trees are usually taller than 150 feet. Second layer is the canopy which is between 75-120 feet. The canopy blocks most sunlight from the bottom layers of the forest. It also contains 50% of the wildlife in a tropical rain forest, including birds, snakes and monkeys.

The shrub layer has the most plant growth. It contains shrubs, ferns and other plants that don't need as much sunlight. The forest floor is usually dark and damp. It contains a layer of rotting leaves and dead animals called "litter". The "liter" decomposes rapidly, within weeks, to form a thin layer of soil rich in nutrients.

Rain forests cover 6% of the earth's surface area. Forty-Seven percent of the worlds rain forests exist in: Latin America, Africa, and Asia. This small amount area is being degraded intensely, and very rapidly. Since 1950, planet Earth has seen it's forests being depleted. An example of destruction of rain forests since 1950 is: in Haiti where they've lost 99% of it's original forest; the Philippine which lost 97% of it's forest; and Madagascar which has lost 84%.

In 1970 deforestation accounted for 1%, now in 2000 it accounts for 15%. Penn State predicts that in 50 years, Brazil's Amazon forest will be completely gone. Per second, two football fields are being cut down. 78 million acres (the size of Poland) are deforested. At this rate my grandchildren may never have the chance to see what a uncontrolled forest looks like outside of a park.

The only deforestation that doesn't really harm earth is carried out by locals, called "slash and burn." It's the process that locals clear forests by slashing the trees down, and burning their remains, and this process returns ashes to the soils, which add nutrients. This is called shifting cultivation. It is a sustainable method of farming in the rainforest.

Some of the things that are terribly ruining our tropical forests are: commercial logging which is responsible for destroying 5 million acres a year, cattle ranching which has replaced lowland forests since 1950, farming in Brazil which nutrients in the soil are quickly exhausted as there is no longer a humus layer to provide nutrients. The soil becomes infertile and nothing will grow. Nutrients in the soil are quickly exhausted as there is no longer a humus layer to provide nutrients. The soil becomes infertile and nothing will grow.

There are many parts in a rain forest like lianas, which are vines, that grow to compete for sunlight in rainforests, climbing high into the tree's canopy. Other parts are buttresses which are plants that eventually grow into the root of the main tree. Others, like the stilt roots which help palms that it's roots are very shallow in the desert. A stilt root can grow up to 24 inches a month, and help provide water to it's neighbor, the palm. Orchids, bromeliads, ferns, or epiphytes, are plants that live on the surface of other plants. They live on the trunk and branches of others, and as they grow they take advantage of the sunlight from the canopy.

Bromeliads which are plants that hold water, their leaves hold water, or grow close to their ground giving natural habitats to insects. Their leaves form a vase or tank that holds water. Small roots can give support to trees and their branches. Their broad leaf bases form a water-holding tank or cup. The tank's capacity ranges from half a pint to 12 gallons or more. The tanks support a thriving eco-system of bacteria, protozoa, tiny crustaceans, mosquito and dragonfly larvae, tadpoles, birds, salamanders and frogs.

Mangroves, which are trees that live on tropical deltas and along ocean estuaries, have adapted to living in wet, marshy conditions and their roots form stabilization for deltas being eroded.

Our lives are enriched by beautiful hardwoods, spices, essential oils and fruits that come from many of these forests. In addition, countries export many fibers, gums, resins, dyes, and plant essences that we may never see directly, but which are widely used in medicine and industry.

IV. Temperate Forest

Living In The Environment describes a temperate forest as a forest that grow in areas with moderate average temperatures that change significantly with moderate average temperatures that change significantly with the season. They are areas that have long summers, cold winters, and abundant precipitation. (4)

Where tropical rainforest lay close to the equator, temperate rain forests lie close to the coastlands, like the Pacific Northwest. In drier, temperate forests have a thick bark that helps to limit moisture evaporation from the tree's trunk. This is not a concern in the high humidity of tropical rainforests; most trees have a thin, smooth bark.

The word "deciduous" means exactly what the leaves on these trees do: change color in autumn, fall off in the winter, and grow back again in the spring. This adaptation helps trees in the forest survive winter.

In temperate forests, there are four seasons, spring, summer, winter, and fall. During the shorter days and cooler weather of autumn, green chlorophyll in the leaves begins to decompose, revealing brilliant oranges, yellows, and reds.

To prepare for winter, deciduous trees and plants become dormant. They loose their leaves and seal the places where leaves were attached with a protective covering called a leaf scar. If they kept their leaves, the water in the leaves would freeze into ice.

Temperate rain forests house many of the common species of animals, birds, and reptiles that we are most familiar with. For examples, the black bear, gray squirrel, raccoon, white-tailed deer, and wild boar, squirrels, rabbits, skunks, birds, deer, mountain lion, bobcat, timber wolf, fox, and black bear. Some common birds in temperate forests are the cardinal, turkey, yellow-bellied sapsucker.

The primary producers in temperate forests consist of coniferous trees, tall Douglas firs, spruce, and cedars, smaller trees and deciduous shrubs, mosses, ferns, grasses, and wild flowers. Primary Consumers include slugs, snails, centipedes, and many insects. Small mammals, such as squirrels, chipmunks, and wood mice, find plenty to at, as do seed-eating birds. Secondary Consumers include insect-eating birds, frogs, and small hunters such as weasels and foxes. Large predators, such as bears, cougars, and bobcats, form the tertiary consumers, and eat smaller animals.

V. Taiga

A taiga is a moist sub arctic forest dominated by conifers (as in spruce and fir) that begins where the tundra ends. (1)

There are very few species of trees exist in the taiga forests. Normally evergreen spruce, firs, pine, larch or tamarack make up all the taiga's of the world. The cone or spiral shape of these trees adapt to the cold and the physiological drought of winter and the short-growing season.

The northern coniferous forest is found in a broad sub arctic band across Alaska, Canada, Scandinavia, Russia, and China, where the winters are long and cold. Conifers, such as spruce, larch, and fir, are the dominant plants, but lichens and mosses are abundant too. Muskegs, or bogs, occur throughout the region. In Siberia and Russia, the south tundra shades into the taiga, a vast belt of mainly coniferous forests, in which the most common trees are larch, pine, Siberian cedar, and fir. Along the southern edge of the taiga is a transitional forest belt with deciduous trees, such as birch, willow, and poplar.

The taiga is not only home to trees, but species of animals too. The dense growth of the conifers provides shelter and a good breeding ground for small animals: lynx, wolverine, porcupine, snowshoe hare, and a lot of small rodents. Wolves prey on the lynx and other mammals; black bear and grizzly bear munch on berries, nuts, and buds; and mule deer and moose browse on shrubs. A host of plant-eating insects and the birds that devour them are also abundant in the taiga. In Komi Russia, the taiga, covers nearly 70 percent of its territory with spruce and pine trees. Komi has a severe climate marked by winter temperatures that average as low as -4° F and average summer temperatures range from 54° F. The Arctic Circle crosses the northern part of the republic, and ice covers more than 10 percent of Komi's territory.

Alaska is another conifer forest that is often referred to as taiga. The sub arctic climate (taiga) is known for it's low winter and summer temperatures and frequent high winds. While snowfall is low, generally less than 12 inches, blowing snow frequently creates a condition known as "whiteout", in which people cannot differentiate between land and sky, making it extremely easy to become disoriented and lost.

There are so many benefits of taigas. Some of the most practical are: that taiga's are unique to Earth; its self renewing; home to lakes, bogs, marshes, meadows, and rivers; it is the solar powered energy reservoir for the sub-arctic; the ecosystem biodiversity, it makes soil from rock; makes and stores its complex chemical nutrients, it's a natural habitat for all sub-arctic animal life; moss and snow provide insulation; and it's an object for science and sustainable systems.

VI. Savanna

"Treeless plain especially in Florida; a tropical or subtropical grassland containing scattered trees and drought-resistant under-growth."(1) "One type of tropical grassland, called a savanna has a) warm temperatures year round, b) two prolonged dry seasons, c) abundant rain the rest of the year. The largest savannas are in central and southern Africa, but also in central South America, Australia, and Southeast Asia." (4)

In regions of higher rainfall, such as eastern Africa, savanna vegetation is maintained by periodic fires. The fires burns back the forest vegetation by consuming dry grass at the end of the rainy season. These fires help defend against the invasion of trees and shrubs, and stimulate new grass growth. Wild beasts, zebras, and elephants can reduce the invaders on parts that cannot carry a fire.

Summer rainfall is essential for the grass dominance. Unlike grasses and shrubs, trees survive a fire by retaining some moisture in all their above-ground parts throughout the dry season. Almost all species are adapted to survive fires, even with severe burning; most species can re-sprout from the stem bases. During March, violent thunderstorms occur again, this time heralding the rainy season. When the rains come, savanna bunch grasses grow a lot.

Most of the savanna vegetation types are used for grazing, mainly by cattle or game. Urbanization is not a problem, because the hot, moist climate and diseases (sleeping sickness, malaria) stop urban development.

Conservation of savanna is important for recreational sports like the most popular sport on savannas: big game hunting. Historically, the African savanna was a major site of hunting by local tribes and tourist big-game hunters. Now, the savanna is frequented by millions of eco-tourists each year that are willing to pay big bucks to see the savanna.

The most extensive regions of savanna, before they were developed by settlers, occurred between the Great Plains grassland of the mid-west and the deciduous forest of the eastern United States. This savanna originally extended from Minnesota to east Texas.

The savanna has a large range of highly specialized plants and animals. They all depend on the each other to keep the environment in balance. There are over 40 different species of mammals, and up to 16 different species of browsers (those who eat leaves of trees) and grazers in one area. They do this by having their own food preferences, browsing verses grazing, time of day to use a certain area, and different places to go during the dry season.

These different herbivores provide a wide range of food for carnivores, like lions, leopards, cheetahs, jackals and hyenas. Each species has its own preference, making it possible to live side by side and not be in competition for food.

The big problems that human's area causing to the savanna is overgrazing and farming. In many parts of the savannas of Africa people have started using it to graze their cattle and goats. If they don't move around then soon the grasses are completely eaten up. With no vegetation, the savanna turns into a desert. Huge areas of savanna are lost to the Sahara desert every year because of overgrazing and farming.

VII. Agricultural Land

The Earth has about 30,000 plant species with parts that are edible for humans, however, only 15 plant and 8 animal species provide 90% of our calories. Wheat, corn, and rice provide half of those calories on a daily basis.

Two thirds of the planet survives on rice, beans, corn, rice, primarily because people can't afford meat. However, as people have more income, we find more meat consumption. Fish are a rich meat source for those on coastal lands and especially in Asian countries, however, on a global scale, 7% of the world consume fish & shell fish.

Nearly forty percent of the world's agricultural land is seriously degraded, which could undermine the long-term productive capacity of our agriculture. soil degradation has already had significant impacts on the productivity of about 16 percent of the globe's agricultural land. Seventy five percent of crop land in Central America is seriously degraded, 20 percent in Africa (mostly pasture), and 11 percent Asia. The threat to the world's food production is compounded by three disturbing trends: 1.5 billion additional people will be on the planet by 2020, almost all in poorer developing countries, the natural fertility of agricultural soils is generally declining, and it is increasingly difficult to find new land that is fertile enough to expand agricultural to.

The predicted 2030 footprint is not predictable. Over the next thirty years, the nation's population will grow, and these newcomers will need a place to live, work, and play. Under any scenario, there will be some farmland lost. There is no simple solution to protecting farmlands from being converted into developed housing projects, some just think its inevitable that our farmlands will be lost to urbanization, and where will we grow food then?

VIII. Woodland and Shrub-land

Shrub-land characterized by small-leafed deciduous and evergreen shrubs, are found worldwide between 32 and 40 degrees north and south of the equator. Climates in shrub land areas vary from those with distinct wet and dry seasons throughout the year to those with hot, dry summers and cool, moist winters. In North America shrub lands are common throughout the American southwest.

Chaparral is a type of shrub-land community that is dominated by small-leaved evergreen vegetation. Such habitats are characteristic of the Mediterranean type of climate with warm, wet winters and long, dry summers. It gets its name (Spanish chaparra means "scrub oak") is applied to the shrub lands of California and Baja California that are dominated by scrub oak and by the dense shrubs "chamiso shrub" and "manzanita shrub." Chaparral is fire dependent. Fire wipes out old growth, disposes of accumulated "litter", recycles nutrients, and stimulates new, vigorous growth from seeds and sprouts.

The benefits of having shrubs in our communities are the basic fact that we like trees around us because they make life more pleasant. Most of us respond to the presence of trees beyond simply observing their beauty. We feel serene, peaceful, restful and tranquil in a grove of trees. We are "at home" there. Hospital patients have been shown to recover from surgery more quickly when their hospital room offered a view of trees. The strong ties of people and trees are most evident in the resistance of community residents to removing trees to widen streets. Or we note the heroic efforts of individuals and organizations to save particularly large or historic trees in a community.

On a larger scale, shrub lands and woodlands provide many advantageous benefits for wildlife. The landowner benefits from production of biomass for forage, energy, timber, native prairie seeds, or berries and nuts from trees and shrubs. The landowner also benefits from improved fishing, hunting, and wildlife habitat. All residents in general, benefit from improved water quality, lower costs of cleaning sediment from major reservoirs and rivers, and increased diversity for wildlife.

IX. Grasslands

"Grasslands form the ecological zone lying between the deserts and temperate woodlands and include a wide variety of plant communities. Generally occurring in the interior of continents, grasslands are composed of sod-forming grasses and perennial grasses and herbs. Grasslands have been cultivated and used for pasture. When overexploited, they can change into either woodlands or deserts." (4)

To be more general grasslands are "areas dominated by grassy vegetation and maintained by fire, grazing, and drought or freezing temperatures." If it weren't for these maintenance factors, trees and shrubs in many types of grassland would increase and the grassland could eventually become forest.

Grasslands are natural, semi natural, and cultivated. Natural grasslands occupy, or once occupied, large areas of continental landmasses, including the prairies and plains of North America, the pampas of South America, South Africa, and Eurasia. Natural grasslands develop in regions characterized by an annual rainfall, a high rate of evaporation, and annual droughts. Tropical grasslands develop in regions with marked wet and dry seasons. On the periphery of these climatic regions, fire is important in maintaining grasslands by preventing the encroachment of forests in moist regions and desert shrubs in semiarid regions.

Semi natural grassland occupies areas where moisture is sufficient to support forests. These areas resulted from deforestation and will return to trees unless maintained by burning, mowing, or grazing.

Cultivated grasslands, such as hayfields and pastures, are artificially planted and maintained. They usually consist of one or two species of grass and a legume such as clover or alfalfa.

Native grasslands of the world support once supported diverse plants. In North America, large grazing herbivores such as the bison and their large predators were dominant. Now, it's associated with such mammals are herbivorous rodents, including prairie dogs and mice; seed-eating birds; hawks; snakes; and insects, especially grasshoppers.

Grassland soils are very fertile. Due to low rainfall, nutrients in the soil have not washed away, and due to the absence of a tree canopy, the successful grasses have built up organically rich topsoil, good for farming. Because of this, native grasslands of the north temperate regions have been converted to grain crops such as corn and wheat. Herbivores have been replaced by cattle and sheep, and the large predators have been destroyed.

In central North America, tall-grass prairie has decreased by nearly 97%, converted to urban and agricultural areas. Conversion, particularly to croplands and other agro ecosystems, has been the primary reason for the diminishing extent of grasslands globally.

In North Dakota, the grasslands that extend from the Rocky Mountains to the forests of North America have tall prairie grasses, especially the Red River valley. The state consists of scattered brushes or shrubs, and varieties of chokecherries, June berries, wild plums, hawthorns, raspberries, buck brushes, and wild roses.

In central Kansas, the rolling grasslands of the Flint and Smoky hills are it's native grasslands that used to be all grasslands until converted to wheat and corn, an important staple for the cold war.

Nebraska, originally, grasslands covered about 98 percent of the state and forests only 2 percent. Cultivation and grazing have to a large extent changed their composition and stands. Many invaders, such as thistle, cactus, and yucca, are found here now in the grasslands of the Sand Hills where grazing has ran faster than the growing capacity of the grasses. Overgrazed pastures are experiencing an increase in cool-season grasses, such as bluegrass and brome grass which were not natives. Serious invasions of noxious weeds such as leafy spurge and spotted knapweed are occurring across the state.

In Mongolia, families are thriving toward a more settled and prosperous life. They're raising larger goat herds to meet the demand for cashmere and permanently pasturing the herds closer to markets. The grasslands are failing from the assault. Thinning grasses can't protect the topsoil, so more and more of it blows away with the persistent Mongolian wind.

Overgrazing is also an important degrader of grassland condition, especially when livestock numbers are high, animals are confined to small grazing plots without rotation, vegetation is sparse, and soils are easily eroded. And the amount of forage, or livestock food, a grassland can produce depends in part on soil conditions. Indicators show that more than half of all remaining grasslands have some degree of soil degradation. In many regions overgrazing and drought pose a serious threat to the future of grasslands.

X. Lakes and Streams

Lakes are large bodies (i.e. greater than 20 acres) of inland water. Lakes are an essential source of water in the United States. The Great Lakes hold about 20% of the world's fresh surface water supply and 90% of the United States supply. Most of our drinking water, as well as water used for irrigation, industry, and hydropower, comes from freshwater lakes and reservoirs. In addition to these uses, freshwater lakes also provide a resource for recreational activities (boating, swimming, and fishing) and habitats for wildlife.

Lakes and streams in Maine and other parts of North America are taking more time than expected to recover from the effects of acid rain, however some signs already point to a modest recovery. Scientists define recovery of a lake as the return to pre-industrial levels of acidity.

The Great Lakes contain 18 percent of the world's fresh water; Lake Superior alone contains more than 9 percent. Streams and rivers in Michigan, northern Wisconsin, and northeast Minnesota drain into the Great Lakes basin, and the remainder of Wisconsin and Minnesota drain into the Mississippi River basin. The density of lakes, rivers (streams of flowing water that empty into lakes, estuaries, or oceans), and streams is very high compared with the rest of the United States, and with most of the world. The health of these systems is inextricably linked to the current and future well-being of the world as we know it.

XI. Continental Shelf

The web-biological dictionary describes the continental shelf as a shallow, gradually sloping zone extending from the coast a depth that is steep in descent into ocean depths down continental slope. Usually the average shelf averages about 300 feet in depth.

Tides, winds, buoyancy, and remote forcing are important oceanographic factors on the continental shelf. Other oceanographic features include coastal upwelling, estuarine circulation, tidal fronts, tidal gyres, shelf-break fronts, and warm-core rings.

Most sediment on the continental shelf originated as glacial deposits. Glacial till was deposited in some places, while silt from glacial melt water extended widely.

Unlike the land, the ocean bottom has not been modified significantly by the growth of plants and soil formation. However it still is continually being altered on the surface by ocean processes.

Beds of kelp and other marine algae grow on the seabed close to shore, and microscopic phytoplankton occurs both near shore and in most other waters. Most anchored marine plants can occur only to a depth of about 30 m and generally fall into two types: those attached to rocks and those in soft bottom.

Oceanic food chains are based on phytoplankton primary production. Most organisms in the ocean feed on phytoplankton, if only in their juvenile stages. Microscopic phytoplankton is consumed directly by grazing vertebrates, invertebrates and by suspension feeders such as mussels, scallops and oysters. Seaweeds also form the basis for food chains involving grazers such as sea urchins, or a wide variety of detritivores, upon death.

The major commercial fish species are ground fish that live on or near the bottom and include cod, haddock, pollock, halibut, and various species of flatfish. These feed on seabed invertebrates as adults but consume zooplankton as they develop.

Continental shelf is a habitat for 18 federally-endangered species including a variety of sea turtles, shorebirds like the piping plover, and marine mammals like seals and sea lions. It also supports more than three quarters of the nation's commercial fish and shellfish at some point during their life cycles.

XII. Open Ocean

Ocean habitats are broken down into three major groups: the benthos, plants like kelp and animals such as star fish that live on or depend on the bottom; the nekton, like fish and whales; and last plankton, various small microscopic organisms that are carried along by the currents.

Benthic plants and animals live close to land. The shallow-bottom habitat of the benthic zone, hat extends from the shore to the edge of the continental shelf, supports mollusks, and algae and sponges. It's populated with deposit feeders and filter feeders such as the stalked crinoids.

At the end of the continental shelf, in lower and darker water stratums, giant squid may be found. However, further than that is the abyssal zone, the cold, dark waters inhabited by bioluminescent fishes.

Plankton is the dominant life and food source of the ocean. Phytoplankton, which carries on photosynthesis near the water surface, provides food for grazing zooplankton and the fish life it supports. The deepwater and bottom life forms depend on a rain of organic matter from above.

Oceans are being polluted very quickly and very dangerously, from human pollution, to even naturally leaking carbon-dioxide leaking from vents deep on the bottom of ocean floors, and naturally seeping oil, as seen on any Santa Barbarian beach. Human waste, ground-up garbage, water from bathing and plastics all contribute to ocean pollution.

Some toxic wastes from metals and slowly degrading chemicals, from industrial, agricultural, household cleaning, gardening, and automotive products regularly end up in coastal waters.

Plastic six-pack rings choke various animals. Every year, whales and dolphins drown to death, the result of entanglement in drifting fishing gear.

So as you can see, some pollution comes from man made wastes, chemical wastes, garbage waste, but also naturally occurring.

XIII. Tundra

"A level of rolling treeless plain that is characteristic of artic and sub-arctic regions, consists of black mucky soil with permanently frozen subsoil, and has a dominant vegetation of mosses, lichens, herbs, and dwarf shrubs." (1)

A tundra's climate is consists of harsh winters, low average temperatures, little snow or rainfall, and a short summer season. The arctic tundra is influenced by permafrost, a layer of permanently frozen subsoil in the ground. For instance, in Russia far northern provinces, summers are still too cold for trees, so mosses, lichens, and low shrubs grow instead. In Wyoming, the alpine tundra above the timberline is dominated by a variety of grasses and hibiscus plants (herbs, shrubs, or small trees), some that are also found in the Arctic tundra. The temperature during the summer in alpine tundra can be warm during the day, but it can drop to below freezing at night. In Siberia, south of the Arctic Ocean for about 270 miles is the tundra. Most of the tundra is in a permafrost condition, frozen to great depths, however, the top 3 to 4 feet thaws enough in the summer to permit mosses, lichens, flowering plants, stunted shrubs, and hordes of mosquitoes to flourish. In Quebec, with is tundra, mosses, lichens, and low shrubs are the typical ground cover. In the far north part of Norway, at high elevations are tundra regions. Its tundra consists mainly of hardy dwarf shrubs and wildflowers.

XVI. Extreme Desert

Deserts cover about one fifth of the Earth's surface and occur where rainfall is less than 50 cm/year. The four major North American deserts of this type are the Chihuahuan, Sonoran, Mojave and Great Basin.

Rainfall is usually very low and/or concentrated in short bursts between long rainless periods. Evaporation rates regularly exceed rainfall rates. Sometimes rain starts falling and evaporates before reaching the ground.

Soils are shallow, rocky or gravely with good drainage and have no subsurface water. They are coarse because there is less chemical weathering (acid rain). The finer dust and sand particles are blown elsewhere, leaving heavier pieces behind.

Some plants found in extreme deserts include: yuccas, ocotillo, turpentine bush, prickly pears, false mesquite, agaves and brittlebush.

Some animals that you may find include small (active at night) carnivores. The dominant animals are burrowers and kangaroo rats. There are also insects, arachnids, reptiles and birds.

Deserts are increasing in size daily. This is partly due to human actions. Because of poor farming techniques, such as overgrazing and over farming in areas of grasslands, cause serious soil erosion.

XVII. Desert Scrub

Another kind of desert, cold deserts, occurs in the basin and range area of Utah and Nevada and in parts of western Asia, where plenty of vegetation exist in the desert. Soils often have abundant nutrients because they need only water to become very productive and have little or no organic matter.

Typical plants include cactuses, acacias and short-lived annuals. Typical animals include reptiles and ground-dwelling rodents.


1. Biome: terrestrial regions inhabited by certain types of life, especially vegetation. Examples are grasslands, deserts, and forests.

2. Community: populations of all species living and interacting in an area at a particular time.

3. Ecosystem: community of different species interacting with one another and with the chemical and physical factors making up its nonliving environment.

4. Ecological diversity: variety of forests, deserts, grasslands, oceans, streams, lakes, and other biological communities interacting with one another.

5. Ecological footprint: measure of the ecological impact of the consumption of food, wood products, and other resources, for the use of buildings, roads, garbage dumps, and other things that consume land space.

6. Herbivores: plant-eating organism. Examples are deer, sheep, grasshoppers, and zooplankton.

7. Old growth forest: virgin and old, second growth forests that are often hundreds, thousands of years old. Examples include forests of Douglas fir, giant sequoia, and coastal redwoods.

8. Pollution: undesirable change in the physical, chemical, or biological characteristics of air, water, soil, or food that can adversely affect the health, survival or activities of humans or other organisms.


1. Merriam-Webster's Collegiate Dictionary, 10th Edition, © 2001



4. Living In The Environment, 13th Edition, G. Tyler Miller, Jr.








12. BioBookcommecosys.html