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Transcript
Chapter 23 Ecosystems and Biomes 23-1: Energy Roles An organism’s energy role is determined by how it obtains energy and how it interacts with the other living things in its ecosystem. An organism can have one of three energy roles in an ecosystem: 1-Producer 2-Consumer 3-Decomposer All ecosystems energy begins with sunlight. Sunlight enters the ecosystem and autotrophs use it to make their own “food” (aka: sugars, carbohydrates, glucose) through performing photosynthesis. Producers Producer- an organism that can make its own food. Therefore producer is a synonym for autotroph. Producers are the source of all the food in an ecosystem. Examples: grass, trees, plants, algae Q: What happens when ecosystems are where there is no sunlight? (example: rocky, deep soil) A: Certain bacteria in this ecosystem produce their own food using the energy in a gas, hydrogen sulfide, instead of energy from sunlight. Consumers Consumer- obtains energy by feeding on other organisms Therefore consumer is a synonym for heterotroph. Consumers can be a: 1- herbivore 2- carnivore 3- ominivore 4- scavenger Herbivore Carnivore Omnivore Scavenger Definition Consumers that Consumers that Consumers that Carnivores that eat plants only eat animals eat both plants eat dead only and animals animals Examples Caterpillar, deer, cattle Lions, spiders, snakes Crows, goats, humans Vultures, catfish Decomposers Decomposer- an organism that break down wastes and dead organisms and return the raw materials to the environment. Examples of Decomposers: fungi and bacteria Q: Why are decomposers essential for an ecosystem? A: If raw materials were not replaced, new organisms would not be able to grow. Also- If wastes and dead organisms were not somehow removed from the ecosystem, they would pile up until they overwhelmed the living things. Food Chains and Food Webs Order of Energy Transfer 1-Energy enters ecosystems in the form of sunlight. 2-Producers use that energy to produce “food”sugars. 3-Those sugars are then eaten by consumers. 4-Then other consumers eat the first consumer and so on. The movement of energy through an ecosystem can be shown in diagrams called food chains and food webs. Food Chain- a series of events in which one organism eats another and obtains energy. The first organism in a food chain is always a producer. The second organism is called a first-level consumer because it eats the producer. The third organism is called a second-level consumer because it eats the first-level consumer. There can be one or possibly two more levels in some ecosystems. Look at the food chain above. What represents each role? Producer- _____________________ First-level consumer- __________________ Second-level consumer- ________________ Third-level consumer- _________________ Fourth-level consumer- ________________ In most ecosystems, there must be decomposers that return nutrients to the soil. What is the decomposer in the example above? __________________ Food Web- many overlapping food chains in an ecosystem. A food chain only shows one possible path energy can take in an ecosystem. However, that is not realistic because organisms do not eat the same thing day after day. Most producers and consumers are a part of many food chains. Therefore, a food web is a more realistic representation of energy flow in an ecosystem. Look at the food web above. Answer these questions: 1- What is the only producer shown? ______________ 2- Name the three mammals that are first-level consumers. _________________________________________________ 3- What are the two birds that an owl will consume? _________________________________________________ 4- How many different organisms could the snake possibly eat? ________ Energy Pyramids Q: How does an organism in an ecosystem obtain energy? A: By eating another organism Q: What happens to that energy? A: The organism uses some of that energy to move, grow, reproduce and carry out other life functions. Q: What happens to the rest of the energy that is not used? A: The rest of the energy is available for the next organism in the food web. Energy Pyramid- a diagram that shows the amount of energy that moves from one feeding level to another in a food web. The most energy is available at the producer level. Q: On the pyramid below, what organism has the most energy available? _the trees_____ At each level in the pyramid, there is less available energy than the level below. Q: On the pyramid below, what organism has the least amount of energy available? _the lion___ In general, only about 10 % of the energy at one level of a food web (or pyramid) is transferred up to the next level. Q: If there is 100% energy available at the producer level, how much energy will get transferred up to the giraffe level? ___10%____ Q: What happens to the other 90% that doesn’t get passed up to the next level? A: Two things happen to it: It is used for the organism’s life processes and it is lost to heat. Because of this, most food webs only have 3-4 feeding levels. Since 90% is lost at each step, there is not enough energy to support many feeding levels. Notice how there are fewer organisms at each level as you move up (if you actually count organisms)…. That is because as you move up the pyramid, and only 10% gets transferred up, there is less energy to support those consumers. Example: far fewer lions in a grassland than there are giraffes Label the following energy pyramid with the following words: Producers, 1st Level Consumers, 2nd Level Consumers, Top Consumers .1% Top Consumers 1% 2nd Level Consumers 10% 100% 1st Level Consumers Producers Now, label the pyramid with the amount of energy available at each level. Label the following energy pyramid with organisms that would fit into a MARINE (OCEAN) ecosystem. 23-2: Cycles of Matter Recycling Matter The way matter is recycled in ecosystems is similar to the way the metal in old cars is recycled. The supply is limited. If matter could not be recycled, ecosystems would quickly run out of the raw materials necessary for life. Energy, on the other hand is not recycled. Ecosystems must have a constant supply of energy (mostly from the sun). In general: Matter CYCLES and Energy FLOWS in One Direction Examples of Matter: Water, Nitrogen, Carbon, and Oxygen The Water Cycle Water Cycle- the continuous process by which water moves from Earth’s surface to the atmosphere and back. There are three process that are active in the water cycle: 1- Evaporation 2- Condensation 3- Precipitation Evaporation- the process by which molecules of liquid water absorb energy and change to the gas state. Water on the surface of lakes and oceans Water Vapor in the atmosphere Condensation- the process by which a gas changes to a liquid. (water vapor turning into clouds) Water Vapor in the atmosphere Cools and rises Water droplets + particles of dust= clouds Precipitation- the process by which water vapor condenses, grow heavier, and fall in the form of rain, snow, sleet, or hail. Water Droplets In Clouds Grow Heavy Rain, Snow, Sleet, Hail Q: What happens to the rain, snow, sleet, and hail? A: They eventually end back up in bodies of water. Label the water cycle below with evaporation, condensation, and precipitation: Condensation Evaporation Precipitation The Carbon and Oxygen Cycle Carbon and Oxygen Cycle- process in which producers use carbon from carbon dioxide to produce other carboncontaining molecules. This cycle is the basically the same thing we learned in Chapter 2: how animal cells go through the C6H12O6 process of O2 respiration and the products from respiration are used for CO2 plants to go through photosynthesis- and vice versa! The Nitrogen Cycle Just like carbon, nitrogen is a necessary building block of life. The air around you contains 78% nitrogen gas. It seems like it would be easy for organisms to obtain it then right??? Actually, most organisms cannot use nitrogen gas (called “free”- meaning not attached to other elements) directly from the air. It needs to be converted into a usable form. Q: How does “free” nitrogen become usable? A: It has to be “fixed” or combined with other elements to form nitrogen-containing compounds. Examples of nitrogen containing compounds- nitrates, nitrites Nodules- bumps on the roots of plants that bacteria live in to carry out nitrogen fixation. Nitrogen Fixation- the process of changing free nitrogen gas into usable nitrogen compounds. Q: What organism carries out the work of nitrogen fixation? A: Bacteria A real life example of the nitrogen cycle and nitrogen fixation is farmers using bacteria to enrich their fields. In fields of legumes (clover, beans, peas, alfalfa, and peanuts) bacteria live in the nodules of plants in a mutualistic relationship. Remember mutualism is a WIN-WIN. The bacteria feeds on the plant’s sugars. The plant gets a usable form of nitrogen from the bacteria. Ever notice how farmers rotate crops? One year it is corn and the next year it is soybeans…. This is because the soybean years make the soil richer in usable nitrogen for plants because of the bacteria/legume relationship. 23-3: Biogeography Biogeography- the study of where an organism lives. “Bio”- means life “Geo”- means earth Continental Drift- the very slow motion of the continents drifting on a layer of dense hot liquid. A factor of how certain species ended up where they are today is continental drift. An example of how continental drift has effected the distribution of species on the earth is in Australia. When Australia drifted and became its own island continent, the species that ended up there evolved independently. This is what is thought to have happened in continental drift: 200 million years ago: Pangaea existed. Present Day: There are seven separate continents. Means of Dispersal Dispersal- movement of organisms from one place to another. Dispersal can be caused by 1) wind or water, or 2) living things- including humans. Wind and Water Many animals move into new areas by simply walking, swimming or flying there. But plants and other small organisms need assistance getting places. Wind Helps: seeds, spores, tiny organisms Water Helps: leaves, fruit and nuts, some insects Other Living Things-can carry things from one place to another like a duck’s feet carrying algae to a new pond. Humans also play a role in dispersal. As people move around the globe, they bring plants and animals with them. Sometimes it is intentional and sometimes it is unintentional. Native Species- species that have naturally evolved in an area. Exotic Species- when an organism is carried to a new location by humans. Sometime exotic species seem native, because they fit in, and sometimes they cause harm to food webs because they don’t fit in. Limits to Dispersal There are three factors that limit dispersal of a species: 1- physical barriers 2- competition 3- climate Physical Barriers Barriers such as water, mountains, and deserts are hard to cross. These features can limit the movement of organisms. Competition Competition can become a barrier when an organism enters a new area and has to compete for resources or find a niche. Climate Climate- the typical weather pattern in an area over a long period of time. Climate is largely determined by temperature and precipitation. Climate differences keep certain species from moving (or growing) into new areas if their adaptations do not suit the climate. Example: The different plants and animals that inhabit the different elevations of a mountain. 23-4: The Earth’s Biomes Biome - a group of ecosystems with similar climates and organisms. Classifying ecosystems into biomes helps ecologists describe the world. Not all ecologists agree on the exact number and kinds of biomes. Q: What determines biomes? A: climate conditions—temperature and rainfall—in an area that determine its biome. This is because climate limits the distribution of plants in the area. In turn, the types of plants determine the kinds of animals that live there. Map of Earth’s Biomes BOREAL FOREST Tropical Rainforest Location Near the equator Temperature Warm year round Rainfall Year round rain Plants Wide variety of trees: Canopy- tall trees that form a leafy roof Understory- shorter trees and vines Forest Floor Plants- thrive in near darkness Examples: Orchids, Ferns Animals Millions of species of insects Wide variety of birds, amphibians, and reptiles Also: Jaguars, primates, and bats Temperate Rainforest Location Northwest region of Unites States Temperature Four seasons, moderate temperatures, stays cool Rainfall Abundant rain year round (> 300 cm) Plants Large coniferous trees: cedars, redwoods, douglas firs Animals Squirrels, beavers, wolves, bears, variety of birds Desert Location Southwest US, Northern Africa, Middle East, Central Australia Temperature Hot days, cold nights Rainfall Very little rainfall (< 25 cm a year) Plants Cacti Animals Lizards, snakes, scorpions, some birds Grassland: Temperate (Prairie) Location Central US, Middle Asia Temperature Four seasons, moderate temperatures Rainfall Rainy season, more than desert, less than rainforest (25-75 cm) Plants Rich Soil supports the growth of many crops, tall grasses Animals Large herbivores, prairie dogs, snakes, hawks, sparrows, rabbits Grassland: Savanna Location Mid-Southern Africa (closer to the equator than prairies) Temperature Warmer than prairie, typically warm year round Rainfall More rain than prairie (as much as 120 cm) Plants Tall grasses, small trees and shrubs Animals Zebras, rhinos, giraffes, lions Deciduous Forest Location Eastern US (where we live), Central S. America, Europe, Eastern Asia Temperature Cool nights, warm days, four seasons Rainfall Rainy seasons (at least 50 cm) Plants Deciduous trees (oak, maple), ferns, mosses- wide variety due to damp forest floor with decaying leaves Animals Chipmunks, many birds, deer, mice, bear Boreal Forest (also known as Taiga) Location Canada, Northern Asia Temperature Cool-Cold Year round Rainfall Snowy winters and rainy summers Plants Coniferous trees- fir, spruce, hemlock Must have waxy needles to prevent water loss Animals Porcupines, elk, moose, wolves, bears Tundra Location Northern-most Canada and Asia Temperature Very cold year-round Rainfall Very dry “frozen desert”, the soil stays frozen as permafrost Plants Moss, grasses, shrubs, willows, lichens Animals Flies, mosquitos, birds, caribou, hares, foxes Other Biomes (do not fall into the major land biome categories) Mountains As you read in section 3, climate conditions can vary greatly from the base of a mountain to the summit. For this reason, mountains can be the home to a wide variety of plants and animals depending on the particular elevation of the mountain. Ice Some areas on earth are covered by ice year round, such as Greenland and Antarctica. A few organisms are adapted for icy conditions: penguins, polar bears, and seals Freshwater Biomes Photosynthesis is important in water, just like it is on land. However, because water absorbs sunlight, there is only enough light for photosynthesis near the surface or in shallow water Algae is the most important producer in water biomes. Ponds and Lakes- Still Water Plants- ponds are shallow enough to have plants growing throughout. - lakes may only have plant life around the edges. Animals- fish, frogs, insects, snails Streams and Rivers- Moving Water Plants- few plants are adapted to the current, some can anchor in the bottom to provide habitats for animals. Animals- fish like trout and salmon, insects Marine Biomes Marine Biomes are divided into five parts: 1- Estuary 2- Intertidal Zone 3- Neritic Zone 4- Surface Zone 5- Deep Zone Estuary- where freshwater of a river meets the salt water of the ocean. Estuaries are rich habitats for organisms. Many plants, grasses, and algae are producers. Estuaries are home to crabs, worms, clams, oysters, and fish. Intertidal Zone- Part of the shore between the highest tide line and the lowest tide line. Organisms here must be able to withstand the pounding waves, changing water temps, and being exposed to both water and air. Organisms that live here are barnacles, sea stars, clams and crabs. Neritic Zone- Region of shallow water below the low tide line that extends like a shelf into the ocean. A wide variety of fish can inhabit this area. Surface Zone- Area in the open ocean where light only penetrates a few hundred meters. Organisms that live here are: Producers- mainly algae Consumers- tuna, swordfish, whales Deep Zone- the open ocean, below the surface zone where water is completely dark Most organisms here feed on the remains of things that sink from the surface zone. Squid and glow-in-the-dark fish live here. Label the zones of the ocean below. Estuary is not included. Intertidal Zone Neritic Zone Surface Zone Deep Zone Succession Succession- series of predictable changes in a community over time. Examples: gradual physical changes or sudden natural or human disasters There are two types of succession: 1) Primary Succession 2) Secondary Succession 47 Primary Succession- occurs on surfaces where no ecosystem or soil existed before. Examples: after a volcanic eruption, on bare rock when a glacier melts Pioneer Species- first species to occupy an area, often lichens. Secondary Succession- occurs where soil is still present after a disturbance. Examples: abandoned farm land or after a wildfire 48 Primary Succession Bare Rock------lichens----------weeds and grass---------shrubs and trees Secondary Succession Wildfire, soil----weeds and wild flowers----young trees-----mature trees W