Transcript Chapter 6
Chapter 6 Section 2 & 3 Different Biomes Environmental Science Spring 2011 Forest Biomes • • • • Exist where precipitation is plentiful Tropical forests Temperate forests Taiga Tropical Rain Forest • Location and Climate: ▫ ▫ ▫ ▫ ▫ ▫ Located in a belt around equator Humid and warm Precipitation: 200-450cm/year Strong sunlight year round Relative constant temperature year round Warm, wet conditions Tropical Rain Forest • Nutrients: ▫ Nutrient poor soil ▫ Nutrients are within the plants ▫ Organic matter decays quickly in hot, wet conditions ▫ Fungi that live on trees can transfer nutrients from dead organic matter directly to the tree ▫ Butresses or Braces: roots that grow sideways from trees and provide extra support in thin soil Tropical Rain Forest • Layers of the Rain Forest: ▫ Emergent layer: tallest trees which reach heights of 60 to 70m, grow and emerge into the direct sunlight ▫ Canopy (upper and lower): grow more than 30m tall, form a dense layer that absorbs 95% of sunlight, lower canopy receives less sunlight than upper canopy Ephiphytes: use entire surface of a tree to live, grow on tall trees so can have sunlight Tropical Rain Forest • Layers of the Rain Forest: ▫ Understory: little light, plants here are adapted to conditions, most do not grow more than 3.5m tall, usually flat leaves Tropical Rain Forest • Species Diversity: ▫ Greatest amount of species diversity ▫ Most rain forest animals are specialists that use adaptations to capture prey and escape predators Tropical Rain Forest • Threats: ▫ 100 acres are cleared every minute of every day ▫ Habitat destruction: when land inhabited by an organism is destroyed or altered ▫ People are losing their habitat as well ▫ Trade of plants and animals is a threat Temperate Rain Forest • Occurs in North America, Australia, and New Zealand • Precipitation: large amounts • High humidity • Moderate temperatures • Temperate rain forest: pacific northwest houses North America’s only one ▫ Maintain moderate temperature all year, rarely freezes, large amount of rainfall ▫ http://dsc.discovery.com/videos/planet-earthforests-redwood-forest.html Temperate Deciduous Forest • Trees drop broad, flat leaves each fall • Located between 30 and 50 degrees north latitudes • Range of temperatures can be extreme ▫ 35 degrees C in summer to below freezing in winter • Growing season lasts 4 to 6 months • Vegetation changes seasonally • Soil contains more nutrients than tropical rain forests Temperate Deciduous Forest • Plants: ▫ Grow in layers ▫ Tall trees (maple, oak, birch) dominate forest canopy ▫ Small trees and shrubs cover understory ▫ Because the floor gets more light than a rain forest, more plants (ferns, herbs, mosses) can grow ▫ Adapted to survive seasonal changes (shed leaves) Temperate Deciduous Forest • Animals: ▫ Adapted to use the forest plants for food and shelter ▫ Squirrels eat nuts, seeds, and fruits in treetops ▫ Bears feast on leaves and berries ▫ Birds nest in safety of canopy Most migratory ▫ Some mammals reduce activity during winter so that they don’t need as much food for energy Taiga • Northern coniferous forest that stretches in a broad band across the northern hemisphere just below the arctic circle • Winters are long (6-10 months) • Average temperatures below freezing, can fall to -20 degrees Celsius • Plant growth most abundant during summer because of nearly constant sunlight and larger amounts of precipitation Taiga Taiga • Plants: ▫ Conifer: tree with needle-like leaves and seeds that develop in cones Shape of leaves and waxy coating prevents lose of water Cone like shape of trees prevents snow from building up Conifer needles contain substances that make soil acidic when they fall, most plants cannot grow here, one reason why taiga floor has few plants ▫ Soil forms slowly because of climate and acidity of needles- slow decomposition Taiga • Animals: ▫ Many lakes and swamps that attract birds in summer ▫ Most birds migrate south during winter ▫ Food is scarce- some species (jumping mice) burrow underground to hibernate ▫ Some animals have adapted to avoid predation (snowshoe hare) ▫ http://dsc.discovery.com/videos/planet-earthforests-taiga-forest.html Grassland, Desert, and Tundra • Little precipitation • Large trees cannot survive here, biomes dominated by smaller plants • Desert: almost no rainfall, few plants • Savannah, Desert: warm areas with little precipitation • Grassland, Chaparral, Desert: temperate areas • Tundra, Desert: cold areas Savannas • Parts of Africa, western India, northern Australia, and some parts of South America • Grassland • Savanna: tropical biome dominated by grasses, shrubs, and small trees • Rain falls mainly during wet season, lasts only a few months of the year ▫ Only time that plants can grow Savannas • Plants: ▫ Most of rain falls during the wet season, plants must be able to survive prolonged periods of time without water ▫ Dry season: plants lose leaves or die down to the ground ▫ Wet season: start to grow again ▫ Many have large horizontal root systems so can draw water from wide area ▫ Vertical leaves: expose less of their surface area to help conserve water ▫ Some trees lose leaves during dry season to conserve water ▫ Often have thorns or sharp leaves to keep herbivores away Savanna Savannas • Animals: ▫ Grazing herbivores Eat vegetation at different heights ▫ Migratory way of life Follow rains ▫ Predators follow their prey ▫ Many savanna animals give birth during wet season Temperate Grasslands • Cover large areas of the interior of continents • Moderate rainfall, not enough for trees • Prairies of North America, steppes in Asia, veldt in South Africa • Mountains often play a critical role in maintaining grasslands ▫ Ex. Rain clouds release most of moisture as pass over Rocky Mountains, shortgrass prairie just east of Rockies receives so little rain it resembles desert, amount of rain increases as move east, permits taller grasses and shrubs Temperate Grasslands • Plants: ▫ Grasses and wildfires ▫ Single layer of vegetation, many species may be present ▫ Shrubs and trees grow where soil contains extra water ▫ Root systems form dense layers that survive drought and fire ▫ Fertile soil ▫ Summer is hot, winter is cold Plants die back to roots in winter ▫ Rate at which dead plants decay is slower than the rate at which new vegetation is added each year – organic matter accumulates in soil Temperate Grasslands • Animals: ▫ Grazing animals with flat teeth for chewing coarse grasses ▫ Badgers, prairie dogs, burrowing owls, live protected in underground burrows Shield animals from fire and weather and protect from predators on open grassland Temperate Grasslands • Threats: ▫ Farming and overgrazing ▫ Soil erosion ▫ Changes grasslands into less productive, desert like biomes Chaparral • Temperate woodland, fairly dry climate but receives enough rain to support more plants than desert • Scattered tree communities of coniferous trees • Chaparral: temperate shrubland that is found in all 5 parts of the world with a Mediterranean climate • Areas have moderately dry, costal climates, little rain in the summer • Located in middle latitudes 30 degrees north and south of equator Chaparral Chaparral • Plants: ▫ Low-lying, evergreen shrubs and small trees that grow in dense packages ▫ Ex. Chamise, manzanita, scrub oak, olive trees, herbs ▫ Plants have small leathery leaves that retain water Contain oils that promote burning- advantage because fires destroy trees that might compete Chaparral trees adapted to re-sprout from small bits of surviving plant tissues Chaparral • Animals: ▫ Common adaptation is camouflage ▫ Ex. Quail, lizards, chipmunks, mule deer Chaparral • Threats: ▫ Greatest threat is human development ▫ Because chaparral gets a lot of sun, are near oceans, and have mild climates year round humans tend to develop land here Desert • Many kinds, all are the driest places on Earth • Desert: areas that have widely scattered vegetation receive very little rain • Little moisture in the air cause temperature to change rapidly during 24h period ▫ Ranges from 40 degrees C during he day to below freezing during the night • Often located near mountain ranges, which block passage of rain clouds Desert • Plants: ▫ Adapted for obtaining and conserving water ▫ Succulents: cactuses, have thick, fleshy stems and leaves that store water Leaves have waxy coating that prevents water loss, sharp spines keep animals from devouring juicy flesh ▫ Rainfall rarely penetrates deep into soil, so many plants roots spread out just under surface of soil ▫ Many drop leaves in dry conditions ▫ When too dry, die and drop seeds that stay dormant ▫ Some adapted to survive even if water content drops to as low as 30% of their mass Desert • Animals: ▫ Thick, scaly skin to prevent water loss ▫ Estivating: burying themselves in the ground and sleep through dry season Amphibians: spadefoot toad ▫ Elf owl nests in cactus ▫ Desert insects covered with body armor that helps retain water ▫ Most are nocturnal when air is cooler Tundra • Located in northern arctic regions • Winter is too cold and dry to permit the growth of trees • Permafrost: deeper layer of soil ▫ Some permanently frozen throughout the year • Topsoil is very thin • In summer when topsoil thaws, land becomes moist and spongy with bogs Tundra • Plants: ▫ Mosses and lichens Can grow without soil ▫ Soil is thin, plants have wide shallow roots ▫ Most plants are short to keep out of wind and help absorb heat from the sunlit soil in summer ▫ Willow and birch have evolved dwarf forms and grow flat or grow along ground Tundra • Animals: ▫ Migratory birds Food is abundant ▫ Caribou migrate throughout in search of food and water ▫ Wolves roam ▫ Small animals burrow underground during winter ▫ Animals are well insulated ▫ http://dsc.discovery.com/videos/planet-earthpole-to-pole-caribou-migration.html Tundra • Threats: ▫ One of most fragile biomes ▫ Food chains are relatively simple, so are easily disrupted ▫ Conditions are extreme, land is easily damaged and slow to recover ▫ Oil and pollution has disrupted habitat