Biomes

Biomes A biome is a large, distinctive complex of plant communities created and maintained by climate. A study published in 1999 concluded that there are 150 different "ecoregions" in North America alone. But I shall cast my lot with the "lumpers" rather than the "splitters" and lump these into 8 biomes: • tundra • taiga • temperate deciduous forest • scrub forest (called chaparral in California) • grassland • desert • tropical rain forest • temperate rain forest The figure shows the distribution of these 8 biomes around the world. A number of climatic factors interact in the creation and maintenance of a biome. Where precipitation is moderately abundant (40 inches or more per year), and distributed fairly evenly throughout the year, the major determinant is temperature. It is not simply a matter of average temperature, but includes such limiting factors as: • whether it ever freezes; • length of the growing season If there is ample rainfall, we find 4 characteristic biomes as we proceed from the tropics (high temperatures) to the extreme latitudes (low temperatures). In order, they are: • tropical rain forest or jungle • temperate deciduous forest • taiga • tundra Tropical Rain Forest In the Western Hemisphere, the tropical rain forest reaches its fullest development in the jungles of Central and South America. • The trees are very tall and of a great variety of species. • One rarely finds two trees of the same species growing close to one another. • The vegetation is so dense that little light reaches the forest floor. • Most of the plants are evergreen, not deciduous. • The branches of the trees are festooned with vines and epiphytes Epiphytes are plants that live perched on sturdier plants. They do not take nourishment from their host as parasitic plants do. Because their roots do not reach the ground, they depend on the air to bring them moisture and inorganic nutrients. Many orchids and many bromeliads (members of the pineapple family like

"Spanish moss") are epiphytes. The lushness of the tropical rain forest suggests a high net productivity, but this is illusory. Many of the frequent attempts to use the tropical rain forest for conventional crops have been disappointing. Two problems: • The high rainfall leaches soil minerals below the reach of plant roots. • The warmth and moisture cause rapid decay so little humus is added to the soil. The tropical rain forest exceeds all the other biomes in the diversity of its animals as well as plants. Most of the animals — mammals and reptiles, as well as birds and insects — live in the trees. The closest thing to a tropical rain forest in the continental United States are the little wooded "islands" found scattered through the Everglades in the southern tip of Florida. Their existence depends on the fact that it never freezes, and they often escape the fires that periodically sweep the Everglades. Temperate Deciduous Forest This biome occupies the eastern half of the United States and a large portion of Europe. It is characterized by: • hardwood trees (e.g., beech, maple, oak, hickory) which • are deciduous; that is, shed their leaves in the autumn. • The number of different species is far more limited than in the jungle. • Large stands dominated by a single species are common. • Deer, raccoons, and salamanders are characteristic inhabitants. • During the growing season, this biome can be quite productive in both natural and agricultural ecosystems. Taiga The taiga is named after the biome in Russia. • It is a land dominated by conifers, especially spruces and firs. • It is dotted with lakes, bogs, and marshes. • It is populated by an even more limited variety of plants and animals than is the temperate deciduous forest. • In North America, the moose is such a typical member that it has led to the name: "spruce-moose" biome. • Before the long, snowy winter sets in, many of the mammals hibernate, and many of the birds migrate south. • Although the long days of summer permit plants to grow luxuriantly, net productivity is low. Tundra

At extreme latitudes, the trees of the taiga become stunted by the harshness of the subarctic climate. Finally, they disappear leaving a land of bogs and lakes. • The climate is so cold in winter that even the long days of summer are unable to thaw the permafrost beneath the surface layers of soil. • Sphagnum moss, a wide variety of lichens, and some grasses and fast-growing annuals dominate the landscape during the short growing season. • Caribou feed on this growth as do vast numbers of insects. • Swarms of migrating birds, especially waterfowl, invade the tundra in the summer to raise their young, feeding them on a large variety of aquatic invertebrates and vertebrates. • As the brief arctic summer draws to a close, the birds fly south, and • all but a few of the permanent residents, in one way or another, prepare themselves to spend the winter in a dormant state. Biomes established by altitude Temperature is the major influence on the biomes discussed above. Because temperatures decline with altitude as well as latitude, similar biomes exist on mountains even when they are at low latitudes. As a rule of thumb, a climb of 1000 feet is equivalent in changed flora and fauna to a trip northward of some 600 miles. The photo is of alpine tundra at 12,000 feet in the Rocky Mountains. Biomes established by rainfall The other major biomes are controlled not so much by temperature but by the amount and seasonal distribution of rainfall. The prevailing winds in the western half of North America blow in from the Pacific laden with moisture. Each time this air rises up from the western slopes of, successively, the Coast Ranges, the Sierras and Cascades, and finally the Rockies, it expands and cools. Its moisture condenses to rain or snow, which drenches the mountain slopes beneath. When the air reaches the eastern slopes, it is relatively dry, and much less precipitation falls. How much falls and when determine whether the biome will be • temperate rain forest • grassland • desert or • chaparral Temperate Rain Forest The temperate rain forest combines high annual rainfall with a temperate climate. The Olympic Peninsular in North America is a good example. An annual rainfall of as much as 150 inches produces a lush forest of conifers. Grasslands

Grasslands are also known as prairie or plains. The annual precipitation in the grasslands averages 20 in./year. A large proportion of this falls as rain early in the growing season. This promotes a vigorous growth of perennial grasses and herbs, but — except along river valleys — is barely adequate for the growth of forests. The photo shows grassland in the Badlands National Monument in South Dakota. Fire is probably the factor that tips the balance from forest to grasslands. Fires — set by lightning and by humans — regularly swept the plains in earlier times. Thanks to their underground stems and buds, perennial grasses and herbs are not harmed by fires that destroy most shrubs and trees. The abundance of grass for food, coupled with the lack of shelter from predators, produces similar animal populations in grasslands throughout the world. The dominant vertebrates are swiftly-moving, herbivorous ungulates. In North America, bison and antelope were conspicuous members of the grassland fauna before the coming of white settlers. Now the level grasslands supply corn, wheat, and other grains, and the hillier areas support domesticated ungulates: cattle and sheep. When cultivated carefully, the grassland biome is capable of high net productivity. A major reason: rainfall in this biome never leaches soil minerals below the reach of the roots of crop plants. Desert Annual rainfall in the desert is less than 10 in. and, in some years, may be zero. Because of the extreme dryness of the desert, its colonization is limited to • plants such as cacti, sagebrush, and mesquite that have a number of adaptations that conserve water over long periods; • fast-growing annuals whose seeds can germinate, develop to maturity, flower, and produce a new crop of seeds all within a few weeks following a rare, soaking rain. The photo shows the desert in the Anza-Borego park in southern California. Many of the animals in the desert (mammals, lizards and snakes, insects, and even some birds) are adapted for burrowing to escape the scorching heat of the desert sun. Many of them limit their forays for food to the night. The net productivity of the desert is low. High productivity can sometimes be achieved with irrigation, but these gains are often only temporary. The high rates of evaporation cause minerals to accumulate near the surface and soon their concentration may reach levels toxic to plants. Chaparral The annual rainfall in the chaparral biome may reach 20–30 in., but in contrast to the grasslands,

almost all of this falls in winter. Summers are very dry and all the plants — trees, shrubs, and grasses — are more or less dormant then. The chaparral is found in California. (The photo shows the chaparral-clad foothills of the Sierra Nevada in California.) Similar biomes (with other names, such as scrub forest, are found around much of the Mediterranean Sea and along the southern coast of Australia. The trees in the chaparral are mostly oaks, both deciduous and evergreen. Scrub oaks and shrubs like manzanita and the California lilac (not a relative of the eastern lilac) form dense, evergreen thickets. All of these plants are adapted to drought by such mechanisms as waxy, waterproof coatings on their leaves. The chaparral has many plants brought to it from similar biomes elsewhere. Vineyards, olives, and figs flourish just as they do in their native Mediterranean biome. So, too, do eucalyptus trees transplanted from the equivalent biome in Australia. Marine Biome LOCATION: The marine biome is the biggest biome in the world! It covers about 70% of the earth. It includes five main oceans: the Pacific, Atlantic, Indian, Arctic, and Southern; as well as many smaller Gulfs and Bays. Marine regions are usually very salty! There is about one cup of salt per gallon of water in the ocean. The ocean is divided up into three vertical zones. The top layer is called the euphotic zone, and it is there area of the ocean where light can penetrate. The next layer is the disphotic zone. This area is too deep for lots of light to reach. Instead, the light here looks like our twilight on land. The deepest part of the ocean is called the aphotic zone, or deep sea. The water here is awfully cold, completely dark, and low in nutritional content. The deep sea comprises 80% of all the habitats on earth, which makes it the largest habitat on the planet. The deepest point in the ocean, the Mariana Trench is deeper than Mt. Everest is tall! The Mariana Trench is about 36,200 feet deep. WEATHER: Climate does not have much affect on the marine biome, but the marine biome largely affects our terrestrial climate! It provides rain for crops through evaporation, wind to help circulate air, and affects coastal temperatures. The ocean is a large influence on whether the weather may be sunny or cloudy, especially here in Santa Barbara because the ocean is right out our back door! The constant motion of the ocean results in currents and waves that may either be warm or cold depending on the weather and temperature of that area. Temperatures in the ocean range from just around freezing at the pole and in the deep waters, to tropical clear waters that are as warm as a bathtub. The average temperature of all oceans is about 39°F. Heat from the sun

warms only the surface of the water. Deep down, oceans everywhere are cold and dark. PLANTS: Over 1 million species of plants and animals have been discovered in the oceans, and scientists say there may be as many as 9 million species we haven't found yet. One reason the ocean is very important is because of all the algae. If it weren't for marine algae we would not be able to breathe! Through photosynthesis, marine plants and algae provide much of the worlds oxygen supply and take in huge amounts of carbon dioxide. This absorption of carbon dioxide may be a useful tool in reducing the severity of climate change. One type of marine algae is kelp. Kelp is important because it provides shelter and food for a lot of sea creatures. Kelp is also used by humans for many products, including toothpaste and ice cream. Kelp also serves as a buffer by absorbing energy from waves before the waves hit the shoreline, protecting many of the sandy beaches along the California coast. Another important marine plant is phytoplankton. These are tiny plants that serve as food to many of the ocean creatures from the smallest of fish to large whales. Some scientists estimate that phytoplankton provide the earth with almost half of its oxygen! Marine plants live in the euphotic zone of the ocean because they need energy from the sun for photosynthesis. ANIMALS: The Earth's oceans are home to most of the planet’s biodiversity. Here we can find mollusks, fish, whales, crustaceans, bacteria, fungi, sea anemones and many other animals. Animals have to deal with unique living situations in all zones of the ocean. The ocean is a salty place that is often cold. Many animals have special adaptations to handle this difficult environment. Most marine mammals have blubber to survive in the cold water, but sea otters are unique because they don’t have blubber. Instead, they have fur more dense than any other mammal, with up to one million hairs per square inch. Most people have ten times less than that on their heads! The ocean can also support very large life forms. The blue whale is the biggest animal on earth. It can be over 100 feet long. Blue whales are so large that a small person could crawl through their main arteries, and 20 people could stand on their tongue! Animals in the deep sea also live in a tough environment. One creature, the anglerfish, deals with the darkness by attracting its prey with a lure lit up by light producing bacteria. When the prey is drawn to the lure, the anglerfish captures it with its big mouth for a tasty meal. PEOPLE AND THIS BIOME: Do you like seafood? How about snorkeling or surfing? People everywhere heavily use the ocean for food, medicines, oil, other resources, and recreation. Demand for resources from the ocean is

damaging ecosystems and depleting these resources. Around the world, unsustainable fishing practices, including the poisoning and dynamiting of coral reefs, catching unwanted fish, dragging nets on the sea floor, overfishing popular species, and fishing in critical reproductive areas are making the problem worse. Pollution is also harming the marine ecosystem. Pollutants, like fertilizers and household products put down the drain make their way through streams and rivers into estuaries, and eventually to the ocean where they badly disrupt the ecosystem and can cause harm to sea life. Oil spills are also a large source of pollution in the oceans. Many organizations and people are currently trying to help protect and clean our oceans. There are many simple things that you can do to help protect the ocean. Recycling, and making sure that chemicals don’t go down your household drains is an easy way to start. Also, cut all of your 6 pack rings before you throw them away. This will keep sea creatures from getting caught in the plastic rings. Buy seafood that is sustainably harvested to make sure that more sea creatures don’t get hurt by fishing. Lastly, learn more about the ocean, with knowledge you will be able to help save our threatened oceans. The freshwater and marine biomes are probably the most important of all the biomes. Their medium, water, is a major natural resource. Water is the basis of life, it supports life, and countless species live in it for all or part of their lives. Freshwater biomes supply us with our drinking water and water for crop irrigation. The world's oceans have an even greater effect on global climate than forests do. Water has a high capacity for heat, and because the Earth is mostly covered with water, the temperature of the atmosphere is kept fairly constant and able to support life. In addition to this climate-buffering capacity, the oceans contain several billion photosynthetic plankton which account for most of the photosynthesis occuring on Earth. Without these, there might not be enough oxygen to support such a large world population and complex animal life. Freshwater biomes have suffered mainly from pollution. Runoff containing fertilizer and other wastes and industrial dumpings enter into rivers, ponds, and lakes and tend to promote abnormally rapid algae growth. When these algae die, dead organic matter accumulates in the water. This makes the water unusable and it kills many of the organisms living in the habitat. Stricter laws have helped to slow down this thoughtless pollution. Overfishing and pollution have threatened to make oceans into ecological disaster areas. Industrial pollutants that are dumped upstream of estuaries have rendered many marine habitats unsuitable for life. Again, tighter regulations have

been used to prevent further destruction of the ocean biomes. By educating people about the consequences of our actions, we can all gain a better understanding of how to preserve the Earth's natural biomes. The areas that have been destroyed the most will never regain their original forms, but conservation will help to keep them from getting worse. The tundra biome Tundra is the coldest of all the biomes. Tundra comes from the Finnish word tunturi, meaning treeless plain. It is noted for its frost-molded landscapes, extremely low temperatures, little precipitation, poor nutrients, and short growing seasons. Dead organic material functions as a nutrient pool. The two major nutrients are nitrogen and phosphorus. Nitrogen is created by biological fixation, and phosphorus is created by precipitation. Characteristics of tundra include: Extremely cold climate Low biotic diversity Simple vegetation structure Limitation of drainage Short season of growth and reproduction Energy and nutrients in the form of dead organic material Large population oscillations Tundra is separated into two types: -Arctic tundra -Alpine tundra 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 foliose 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, arctic hares and squirrels Carnivorous mammals: arctic foxes, wolves, and polar bears Migratory birds: ravens, snow buntings, falcons, loons, ravens, sandpipers, terns, snow birds, and various species of gulls Insects: mosquitoes, flies, moths, grasshoppers, blackflies and arctic bumble bees 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, marmots, mountain goats, sheep, elk Birds: grouselike birds Insects: springtails, beetles, grasshoppers, butterflies The desert biome Deserts cover about one fifth of the Earth's surface and occur where rainfall is less than 50 cm/year. Although most deserts, such as the Sahara of North Africa and the deserts of the southwestern U.S., Mexico, and Australia, occur at low latitudes, another kind of desert, cold deserts, occur in the basin and range area of Utah and Nevada and in parts of western Asia. Most deserts have a considerable amount of specialized vegetation, as well as specialized vertebrate and invertebrate animals. Soils often have abundant nutrients because they need only water to become very productive and have little or no organic matter. Disturbances are common

in the form of occasional fires or cold weather, and sudden, infrequent, but intense rains that cause flooding. There are relatively few large mammals in deserts because most are not capable of storing sufficient water and withstanding the heat. Deserts often provide little shelter from the sun for large animals. The dominant animals of warm deserts are nonmammalian vertebrates, such as reptiles. Mammals are usually small, like the kangaroo mice of North American deserts. Desert biomes can be classified according to several characteristics. There are four major types of deserts: Hot and dry Semiarid Coastal Cold Hot and dry desert The four major North American deserts of this type are the Chihuahuan, Sonoran, Mojave and Great Basin. Others outside the U.S. include the Southern Asian realm, Neotropical (South and Central America), Ethiopian (Africa) and Australian. The seasons are generally warm throughout the year and very hot in the summer. The winters usually bring little rainfall. Temperatures exhibit daily extremes because the atmosphere contains little humidity to block the Sun's rays. Desert surfaces receive a little more than twice the solar radiation received by humid regions and lose almost twice as much heat at night. Many mean annual temperatures range from 20-25° C. The extreme maximum ranges from 43.5-49° C. Minimum temperatures sometimes drop to -18° C. 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. Rainfall is lowest on the Atacama Desert of Chile, where it averages less than 1.5 cm. Some years are even rainless. Inland Sahara also receives less than 1.5 cm a year. Rainfall in American deserts is higher — almost 28 cm a year. Soils are course-textured, shallow, rocky or gravely with good drainage and have no subsurface water. They are coarse because there is less chemical weathering. The finer dust and sand particles are blown elsewhere, leaving heavier pieces behind. Canopy in most deserts is very rare. Plants are mainly ground-hugging shrubs and short woody

trees. Leaves are "replete" (fully supported with nutrients) with water-conserving characteristics. They tend to be small, thick and covered with a thick cuticle (outer layer). In the cacti, the leaves are much-reduced (to spines) and photosynthetic activity is restricted to the stems. Some plants open their stomata (microscopic openings in the epidermis of leaves that allow for gas exchange) only at night when evaporation rates are lowest. These plants include: yuccas, ocotillo, turpentine bush, prickly pears, false mesquite, sotol, ephedras, agaves and brittlebush. The animals include small nocturnal (active at night) carnivores. The dominant animals are burrowers and kangaroo rats. There are also insects, arachnids, reptiles and birds. The animals stay inactive in protected hideaways during the hot day and come out to forage at dusk, dawn or at night, when the desert is cooler. Semiarid desert The major deserts of this type include the sagebrush of Utah, Montana and Great Basin. They also include the Nearctic realm (North America, Newfoundland, Greenland, Russia, Europe and northern Asia). The summers are moderately long and dry, and like hot deserts, the winters normally bring low concentrations of rainfall. Summer temperatures usually average between 21-27° C. It normally does not go above 38° C and evening temperatures are cool, at around 10° C. Cool nights help both plants and animals by reducing moisture loss from transpiration, sweating and breathing. Furthermore, condensation of dew caused by night cooling may equal or exceed the rainfall received by some deserts. As in the hot desert, rainfall is often very low and/or concentrated. The average rainfall ranges from 24 cm annually. The soil can range from sandy and fine-textured to loose rock fragments, gravel or sand. It has a fairly low salt concentration, compared to deserts which receive a lot of rain (acquiring higher salt concentrations as a result). In areas such as mountain slopes, the soil is shallow, rocky or gravely with good drainage. In the upper bajada (lower slopes) they are coarse-textured, rocky, well-drained and partly "laid by rock bench." In the lower bajada (bottom land) the soil is sandy and fine-textured, often with "caliche hardpan." In each case there is no subsurface water. The spiny nature of many plants in semiarid deserts provides protection in a hazardous environment. The large numbers of spines shade the surface enough to significantly reduce transpiration. The same may be true of the hairs on the woolly desert plants. Many plants have

silvery or glossy leaves, allowing them to reflect more radiant energy. These plants often have an unfavorable odor or taste. Semiarid plants include: Creosote bush, bur sage (Franseria dumosa or F. deltoidea), white thorn, cat claw, mesquite, brittle bushes (Encelia farinosa), lyciums, and jujube. During the day, insects move around twigs to stay on the shady side; jack rabbits follow the moving shadow of a cactus or shrub. Naturally, many animals find protection in underground burrows where they are insulated from both heat and aridity. These animals include mammals such as the kangaroo rats, rabbits, and skunks; insects like grasshoppers and ants; reptiles are represented by lizards and snakes; and birds such as burrowing owls and the California thrasher. Coastal desert These deserts occur in moderately cool to warm areas such as the Nearctic and Neotropical realm. A good example is the Atacama of Chile. The cool winters of coastal deserts are followed by moderately long, warm summers. The average summer temperature ranges from 13-24° C; winter temperatures are 5° C or below. The maximum annual temperature is about 35° C and the minimum is about -4° C. In Chile, the temperature ranges from -2 to 5° C in July and 21-25° C in January. The average rainfall measures 8-13 cm in many areas. The maximum annual precipitation over a long period of years has been 37 cm with a minimum of 5 cm. The soil is fine-textured with a moderate salt content. It is fairly porous with good drainage. Some plants have extensive root systems close to the surface where they can take advantage of any rain showers. All of the plants with thick and fleshy leaves or stems can take in large quantities of water when it is available and store it for future use. In some plants, the surfaces are corrugated with longitudinal ridges and grooves. When water is available, the stem swells so that the grooves are shallow and the ridges far apart. As the water is used, the stem shrinks so that the grooves are deep and ridges close together. The plants living in this type of desert include the salt bush, buckwheat bush, black bush, rice grass, little leaf horsebrush, black sage, and chrysothamnus. Some animals have specialized adaptations for dealing with the desert heat and lack of water. Some toads seal themselves in burrows with gelatinous secretions and remain inactive for eight or nine months until a heavy rain occurs.

Amphibians that pass through larval stages have accelerated life cycles, which improves their chances of reaching maturity before the waters evaporate. Some insects lay eggs that remain dormant until the environmental conditions are suitable for hatching. The fairy shrimps also lay dormant eggs. Other animals include: insects, mammals (coyote and badger), amphibians (toads), birds (great horned owl, golden eagle and the bald eagle), and reptiles (lizards and snakes). Cold desert These deserts are characterized by cold winters with snowfall and high overall rainfall throughout the winter and occasionally over the summer. They occur in the Antarctic, Greenland and the Nearctic realm. They have short, moist, and moderately warm summers with fairly long, cold winters. The mean winter temperature is between -2 to 4° C and the mean summer temperature is between 21-26° C. The winters receive quite a bit of snow. The mean annual precipitation ranges from 15-26 cm. Annual precipitation has reached a maximum of 46 cm and a minimum of 9 cm. The heaviest rainfall of the spring is usually in April or May. In some areas, rainfall can be heavy in autumn. The soil is heavy, silty, and salty. It contains alluvial fans where soil is relatively porous and drainage is good so that most of the salt has been leached out. The plants are widely scattered. In areas of shadscale, about 10 percent of the ground is covered, but in some areas of sagebush it approaches 85 percent. Plant heights vary between 15 cm and 122 cm. The main plants are deciduous, most having spiny leaves. Widely distributed animals are jack rabbits, kangaroo rats, kangaroo mice, pocket mice, grasshopper mice, and antelope ground squirrels. In areas like Utah, population density of these animals can range from 14-41 individuals per hectare. All except the jack rabbits are burrowers. The burrowing habit also applies to carnivores like the badger, kit fox, and coyote. Several lizards do some burrowing and moving of soil. Deer are found only in the winter. The freshwater biome Freshwater is defined as having a low salt concentration — usually less than 1%. Plants and animals in freshwater regions are adjusted to the low salt content and would not be able to survive in areas of high salt concentration (i.e., ocean). There are different types of freshwater regions: Ponds and lakes Streams and rivers Wetlands

Ponds and lakes These regions range in size from just a few square meters to thousands of square kilometers. Scattered throughout the earth, several are remnants from the Pleistocene glaciation. Many ponds are seasonal, lasting just a couple of months (such as sessile pools) while lakes may exist for hundreds of years or more. Ponds and lakes may have limited species diversity since they are often isolated from one another and from other water sources like rivers and oceans. Lakes and ponds are divided into three different “zones” which are usually determined by depth and distance from the shoreline. The topmost zone near the shore of a lake or pond is the littoral zone. This zone is the warmest since it is shallow and can absorb more of the Sun's heat. It sustains a fairly diverse community, which can include several species of algae (like diatoms), rooted and floating aquatic plants, grazing snails, clams, insects, crustaceans, fishes, and amphibians. In the case of the insects, such as dragonflies and midges, only the egg and larvae stages are found in this zone. The vegetation and animals living in the littoral zone are food for other creatures such as turtles, snakes, and ducks. The near-surface open water surrounded by the littoral zone is the limnetic zone. The limnetic zone is well-lighted (like the littoral zone) and is dominated by plankton, both phytoplankton and zooplankton. Plankton are small organisms that play a crucial role in the food chain. Without aquatic plankton, there would be few living organisms in the world, and certainly no humans. A variety of freshwater fish also occupy this zone. Plankton have short life spans — when they die, they fall into the deep-water part of the lake/pond, the profundal zone. This zone is much colder and denser than the other two. Little light penetrates all the way through the limnetic zone into the profundal zone. The fauna are heterotrophs, meaning that they eat dead organisms and use oxygen for cellular respiration. Temperature varies in ponds and lakes seasonally. During the summer, the temperature can range from 4° C near the bottom to 22° C at the top. During the winter, the temperature at the bottom can be 4° C while the top is 0° C (ice). In between the two layers, there is a narrow zone called the thermocline where the temperature of the water changes rapidly. During the spring and fall seasons, there is a mixing of the top and bottom layers, usually due to winds, which results in a uniform water temperature of around 4° C. This mixing also circulates oxygen throughout the

lake. Of course there are many lakes and ponds that do not freeze during the winter, thus the top layer would be a little warmer. Streams and rivers These are bodies of flowing water moving in one direction. Streams and rivers can be found everywhere — they get their starts at headwaters, which may be springs, snowmelt or even lakes, and then travel all the way to their mouths, usually another water channel or the ocean. The characteristics of a river or stream change during the journey from the source to the mouth. The temperature is cooler at the source than it is at the mouth. The water is also clearer, has higher oxygen levels, and freshwater fish such as trout and heterotrophs can be found there. Towards the middle part of the stream/river, the width increases, as does species diversity — numerous aquatic green plants and algae can be found. Toward the mouth of the river/stream, the water becomes murky from all the sediments that it has picked up upstream, decreasing the amount of light that can penetrate through the water. Since there is less light, there is less diversity of flora, and because of the lower oxygen levels, fish that require less oxygen, such as catfish and carp, can be found. Wetlands Wetlands are areas of standing water that support aquatic plants. Marshes, swamps, and bogs are all considered wetlands. Plant species adapted to the very moist and humid conditions are called hydrophytes. These include pond lilies, cattails, sedges, tamarack, and black spruce. Marsh flora also include such species as cypress and gum. Wetlands have the highest species diversity of all ecosystems. Many species of amphibians, reptiles, birds (such as ducks and waders), and furbearers can be found in the wetlands. Wetlands are not considered freshwater ecosystems as there are some, such as salt marshes, that have high salt concentrations — these support different species of animals, such as shrimp, shellfish, and various grasses. Taiga The taiga is the biome of the needleleaf forest. Living in the taiga is cold and lonely. Coldness and food shortages make things very difficult, mostly in the winter. Some of the animals in the taiga hibernate in the winter, some fly south if they can, while some just cooperate with the environment, which is very difficult. (Dillon Bartkus) Taiga is the Russian word for forest and is the largest biome in the world. It stretches over Eurasia and North America. The taiga is located

near the top of the world, just below the tundra biome. The winters in the taiga are very cold with only snowfall. The summers are warm, rainy, and humid. A lot of coniferous trees grow in the taiga. The taiga is also known as the boreal forest. Did you know that Boreal was the Greek goddess of the North Wind? The taiga doesn't have as many plant and animal species as the tropical or the deciduous forest biomes. It does have millions of insects in the summertime. Birds migrate there every year to nest and feed. Here is some information about the temperatures and weather in the taiga. The average temperature is below freezing for six months out of the year. The winter temperature range is -54 to -1° C (-65 to 30° F). The winters, as you can see, are really cold, with lots of snow. Temperature range in the summer gets as low as -7° C (20° F). The high in summer can be 21° C (70° F). The summers are mostly warm, rainy and humid. They are also very short with about 50 to 100 frost free days. The total precipitation in a year is 30 - 85 cm (12 - 33 in) . The forms the precipitation comes in are rain, snow and dew. Most of the precipitation in the taiga falls as rain in the summer. The main seasons in the taiga are winter and summer. The spring and autumn are so short, you hardly know they exist. It is either hot and humid or very cold in the taiga. There are not a lot of species of plants in the taiga because of the harsh conditions. Not many plants can survive the extreme cold of the taiga winter. There are some lichens and mosses, but most plants are coniferous trees like pine, white spruce, hemlock and douglas fir. Coniferous trees are also known as evergreens. They have long, thin waxy needles. The wax gives them some protection from freezing temperatures and from drying out. Evergreens don't loose their leaves in the winter like deciduous trees. They keep their needles all year long. This is so they can start photosynthesis as soon as the weather gets warm. The dark color of evergreen needles allows them to absorb heat from the sun and also helps them start photosynthesis early. Evergreens in the taiga tend to be thin and grow close together. This gives them protection from the cold and wind. Evergreens also are usually shaped like an upside down cone to protects the branches from breaking under the weight of all

that snow. The snow slides right off the slanted branches. The taiga is susceptible to many wildfires. Trees have adapted by growing thick bark. The fires will burn away the upper canopy of the trees and let sunlight reach the ground. New plants will grow and provide food for animals that once could not live there because there were only evergreen trees. Animals of the taiga tend to be predators like the lynx and members of the weasel family like wolverines, bobcat, minks and ermine. They hunt herbivores like snowshoe rabbits, red squirrels and voles. Red deer, elk, and moose can be found in regions of the taiga where more deciduous trees grow. Many insect eating birds come to the taiga to breed. They leave when the breeding season is over. Seed eaters like finches and sparrows, and omnivorous birds like crows stay all year long. Climate Taiga is in Köppen's Dfc climate category. The Dis a snow climate, while the fmeans there is enough precipitation in all months. The cmeans that fewer than 4 months have an average temperature over 50° F (10° C). The taiga climate is for the most part dominated by cold arctic air. Exceptionally cold winds bring bitterly cold air from the Arctic Circle: the temperatures fall even more on clear nights when there is no cloud cover. Because of earth's tilt, the taiga is turned away from the sun in the winter. Less of the sun's radiation reaches the ground to warm it up. Winter, with it's freezing cold temperatures, lasts for six to seven months. Summer is a rainy, hot and short season in the taiga. Fall is the shortest season for taiga. Spring brings flowers, the frozen ponds melt, and the animals come out from hibernation. The lowest and highest temperatures that occur for taiga are the following: Winter's LOWEST temperature in taiga is -65°F. Winter's HIGHEST temperature is 30° F. Summer's LOWEST temperature is 30° F. Summer's HIGHEST temperature is 70° F. The temperature range, as you can see, is -65° F to 70°F (-54 to 21° C). For half of the year, the average temperature is below freezing. In the winter the average air temperature is warmer than it is for tundra, which lies north of the taiga.

The taiga climate has an average annual rainfall of 12 - 33 inches (30 - 84 cm). Most of it falls in the summer as rain. The corresponding biome would be the Taiga biome. The global range for taiga goes all around the world from Alaska, to Canada, Scandinavia, Russia and China. Taiga climate is only found in the northern hemisphere, because there isn't enough land mass in the southern hemisphere to create a taiga climate there. -Over many years, evergreen species have gained adaptations to improve their chances of surviving the taiga. Trees in the temperate deciduous biome drop their leaves in the fall. That way they can survive a heavy snowstorm without risking their branches. Evergreen trees in the taiga keep their leaves, but their cone shape helps prevent damage. Branches droop downward, which helps shed excess snow. If the branches held more snow it would increase the chance of them breaking during a heavy storm. The needles help keep the trees warm during the winter. -Taiga trees tend to be conifers. Conifers, many of which are evergreen, produce cones in late winter or early fall. If a cone becomes fertilized, it grows bigger. Only then do the seeds inside develop. Once the seeds ripen, the cone dries up and the seed falls out. It can take up to two years to produce a mature seed. Squirrels like to feed on these seeds. -Needles on evergreen trees of the taiga are thin and wax-covered. They do not fall off in the fall. Needles are leaves. Most taiga conifers, with the exception of the tamarack and a few other species, keep their leaves in the winter. Most conifers keep their leaves for 2 - 3 years. A spruce can keep its needles for 15 years! Conifers lose their leaves a few at a time, so the change is not always noticeable. Needles are adapted to the taiga environment. Needles lose less water and shed snow more easily than broad leaves. -In the temperate deciduous forest most leaves fall off in autumn. In the taiga, the change is much more subtle. Leaves slow down the chemical process for winter. The tamarack's leaves turn brown and drop. It is one of only a handful of evergreen species that drop their leaves for the fall. The leaves of many shrubs turn deep red. Aspen Trees Birch Trees Aspen and birch, deciduous trees, have leaves that turn golden before falling for the winter. All in all, the taiga fall show is less dramatic than the temperate deciduous show. -