09/11/2013 LEARNING OBJECTIVES BIOMES TOPIC 27 WE LIVE IN ECOSYSTEMS

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1 Elevation (ft) 09/11/2013 TOPIC 27 WE LIVE IN ECOSYSTEMS LEARNING OBJECTIVES CEB Textbook Chapter 18, pages and Chapter 20, pages Mastering Biology, Chapters 18 and 20 Define the term biome and explain how biomes get their names. Describe the two key factors that usually determine what type of biome will exist in a particular region. Give one example of each of the three types of biomes. Understand the concept of biogeochemical cycles. Describe and explain one of the biogeochemical cycle of your choice (carbon, nitrogen or phosphorus) Explain how the global water cycle links aquatic and terrestrial biomes. BIOMES A biome is a major terrestrial or aquatic life zone, characterized by vegetation type in terrestrial biomes or the physical environment in aquatic biomes. Freshwater Biomes cover less than 1% of Earth, contain.01% of its water, 6% of its species, used for all our drinking water!! Marine Biomes cover over 70% of Earth! TERRESTRIAL BIOMES DETERMINED BY CLIMATE AND IDENTIFIED BY VEGETATION TYPE FIGURE MOUNTAINS: TEMPERATURE DROPS AS ELEVATION INCREASES RESULTING IN SEVERAL BIOMES UP A TALL MOUNTAIN Oak woodland Spruce-fir forest Pine woodland 10,000 9,000 8,000 7,000 6,000 HOW CLIMATE AFFECTS BIOME DISTRIBUTION The type of terrestrial biome is usually determined by... Temperature and, Rainfall Desert grassland Desert 5,000 4,000 3,000 1

2 FIGURE FIGURE Low angle of incoming sunlight MORE RAIN AT EQUATOR DUE TO MORE EVAPORATION Sunlight strikes most directly Low angle of incoming sunlight Atmosphere 60º N 30º N Tropic of Cancer 0º (equator) Tropic of Capricorn 30º S 60º S Arctic Circle Antarctic Circle Descending dry air absorbs moisture Temperate zone Trade winds Ascending moist air releases moisture Doldrums 0º Tropics Trade winds Descending dry air absorbs moisture Temperate zone FIGURE AQUATIC BIOMES MOUNTAINS CAN BLOCK COOL AIR COMING FROM THE COAST Pacific Ocean Coast Range Wind direction Sierra Nevada East Rain shadow Desert Climate is also affected by proximity to large bodies of water and the presence of landforms such as mountain s. FIGURE High Low tide tide Pelagic realm Oarweed Sea star Brain coral Phytoplankton Zooplankton Intertidal zone Continental shelf Sponges Man-of-war Turtle Blue shark Sperm whale Photic zone 200 m Twilight AQUATIC BIOMES OCCUPY 75% OF THE EARTHS SURFACE. THEY ARE DETERMINED BY SALINITY AND OTHER PHYSICAL FACTORS Sea pen Benthic realm Hatchet fish Octopus Sea spider Gulper Rat-tail fish eel Brittle star Anglerfish Glass sponge Sea Tripod cucumber fish Aphotic zone 1,000 m No light 6,000 10,000 m 2

3 FIGURE FIGURE Dam RIVER BIOME A stream in the Appalachian Mountains Seattle WA Portland OR ID Canada U.S. Flathead Lake N MT CA NV WETLANDS Marine Biomes A wetland is a transitional biome between an aquatic ecosystem and a terrestrial one. Wetlands support the growth of aquatic plants and are rich in species diversity. A wetland near Kent, Ohio The coral reef biome occurs in the photic zone of warm tropical waters, in scattered locations around the globe. A coral reef in the Red Sea off the coast of Egypt Marine Biomes Marine Biomes The intertidal zone is where the ocean meets land, the shore is pounded by waves during high tide, and the bottom is exposed to the sun and drying winds during low tide. An intertidal zone on the Pacific coast of Washington State Estuaries are a transition area between a river and the ocean, have a saltiness ranging from nearly that of fresh water to that of the ocean, and are among the most productive areas on Earth. Waterfowl in an estuary on the southeast coast of England 3

4 Annual mean temperature (ºC) 09/11/2013 Marine Biomes TERRESTRIAL BIOMES Estuaries are threatened by landfills, nutrient pollution, contamination by pathogens or toxic chemicals, such as the massive Deepwater Horizon oil spill in the Gulf of Mexico in 2010, and alteration of freshwater inflow. FIGURE Terrestrial ecosystems are grouped into biomes primarily on the basis of their vegetation type Annual mean precipitation (cm) Key Tropical forest Desert Temperate grassland Temperate broadleaf forest Coniferous forest Tundra FIGURE TROPICAL FOREST 30º N Tropic of Cancer Equator Tropic of Capricorn 30º S Tropical forests occur in equatorial areas, where the temperature is warm, and days are hours long year-round. Key Tropical forest Savanna Desert Chaparral Temperate grassland Temperate broadleaf forest Coniferous forest Arctic tundra High mountains (coniferous forest and alpine tundra) Polar ice 4

5 Temperature Temperature Fire Temperature 09/11/2013 FIGURE SAVANNA Savannas are dominated by grasses and scattered trees, are warm year-round, and experience rainfall of cm (roughly inches per year) with dramatic seasonal variation. Tropical Rainforest FIGURE DESERT Deserts are the driest of all biomes, are characterized by low and unpredictable rainfall of less than 30 cm (about 12 inches) a year, and may be very hot or very cold. Savanna FIGURE CHAPARRAL Chaparral has a climate that results from cool ocean currents circulating offshore and producing mild, rainy winters and hot, dry summers. Desert 5

6 Temperature Temperature Fire Temperature Fire 09/11/2013 FIGURE TEMPERATE GRASSLAND Temperate grasslands are mostly treeless, have cm (10 30 inches) of rain per year, experience frequent droughts and fires, and are characterized by grazers including bison and pronghorn in North America. Chaparral FIGURE TEMPERATE BROADLEAF FOREST Temperate broadleaf forest occurs throughout midlatitudes where there is sufficient moisture to support the growth of large trees, ranging from 75 to 150 cm (30 to 60 inches), and includes dense stands of deciduous trees in the Northern Hemisphere. Temperate grassland TEMPERATE BROADLEAF FOREST FIGURE Deciduous trees drop their leaves before winter, when temperatures are too low for effective photosynthesis and water lost by evaporation is not easily replaced from frozen soil. Temperate broadleaf forest 6

7 Temperature Temperature Temperature 09/11/2013 CONIFEROUS FOREST FIGURE Coniferous forests are dominated by cone-bearing evergreen trees and include the northern coniferous forest, or taiga, the largest terrestrial biome on Earth. Coniferous forest TUNDRA FIGURE Tundra covers expansive areas of the Arctic between the taiga and polar ice and is characterized by permafrost (permanently frozen subsoil), bitterly cold temperatures, and high winds. Tundra Polar Ice FIGURE Polar ice covers the land at high latitudes north of the arctic tundra in the Northern Hemisphere and in Antarctica in the Southern Hemisphere. Only a small portion of these landmasses is free of ice or snow, even during the summer. Polar Ice 7

8 ECOSYSTEM ECOLOGY FIGURE A simple terrarium is a community that interacts with abiotic factors. 1. Energy flow is the passage of energy through the components of the ecosystem. 2. Chemical cycling is the use and reuse of chemical elements such as carbon and nitrogen within the ecosystem. Energy flows through and ultimately out of ecosystems. Chemicals are recycled within and between ecosystems. Energy flow Light energy Bacteria, protists, and fungi Chemical energy a Chemical elements Heat energy BIOGEOCHEMICAL CYCLES Life depends on the recycling of chemicals. Nutrients are acquired and waste products are released by living organisms. At death, decomposers return the complex molecules of an organism to the environment. The pool of inorganic nutrients is used by plants and other producers to build new organic matter. BIOGEOCHEMICAL CYCLES: Recycling Nutrients Ecosystems need two things in order to exist. What are they? They receive an inexhaustible influx of solar energy, but chemical elements are available only in limited amounts! Life therefore depends on the recycling of essential chemical elements. Microorganisms are especially important in this process because they release compounds of these elements trapped in the bodies of dead organisms. What is this process called? Decay. FIGURE Biogeochemical cycles involve 3 biotic components and abiotic components from an abiotic reservoir where a chemical accumulates or is stockpiled outside of living organisms. Consumers 2 Producers 1 Nutrients available to producers Abiotic reservoir 4 Decomposers The General Scheme of Chemical Cycling Biogeochemical cycles can be local or global. Three important biogeochemical cycles are 1. carbon, 2. nitrogen, and 3. phosphorus Geologic processes 8

9 THE CARBON CYCLE Carbon is a vital building block of all biological molecules. These molecules are synthesized by photosynthetic organisms. Carbon is returned to the atmosphere by respiration. Organisms obtain carbon from the atmosphere, however carbon dioxide only accounts for 0.038% of the gas in the Earth s atmosphere. Variation in the rates of photosynthesis and respiration can give rise to short-term fluctuations in the atmospheric carbon dioxide levels. WHAT IS THE CARBON CYCLE? DECOMPOSITION Decomposition is the breakdown of organic material into simpler compounds by saprotrophic micro-organisms. These include some species of bacteria and fungi. Saprotrophic or saprophytic nutrition describes how decomposers like fungi e.g. Rhizopus or Mucor (bread moulds) obtain their energy. They release hydrolytic enzymes from their hyphae, which break down complex carbon-containing organic molecules. The digested products can then be absorbed and used for respiration. OCEANS Carbon dioxide moves between the atmosphere and the ocean by diffusion. This movement occurs when there is a difference in CO 2 gas pressure between the two. The oceans contain more carbon than the atmosphere, because CO 2 that has diffused into the sea reacts with the water to form carbonic acid and its dissociation products. This effectively reduces the CO 2 gas pressure in the water, allowing more diffusion from the atmosphere. PLANKTON Marine phytoplankton account for a large amount of the global biological uptake of carbon dioxide. They absorb carbon dioxide and release oxygen during photosynthesis. Plankton use carbon to produce calcium carbonate (CaCO 3 ) shells. When plankton die, their shells sink to the ocean floor and are buried in the sediment. Over time this can form limestone and chalk, locking away the carbon. EFFECT OF CARBON DIOXIDE ON THE OCEANS The diffusion of carbon dioxide between the ocean and the atmosphere helps the atmospheric carbon dioxide levels to remain relatively constant during short-term fluctuations. However, scientists are concerned about the impact of increased diffusion. A constant increase in carbonic acid levels and dissociation products could lead to a decrease in ph. This is known as ocean acidification. It is thought that this could slow the rate of growth of coral reefs and affect phytoplankton populations. 9

10 The Carbon Cycle: The Carbon Cycle: Production of carbohydrates, proteins and fats contribute to plant growth and subsequently to animal growth through food webs. Dead remains of plants and animals are acted upon by sapribionts in the soil that eventually releases CO 2 back into the atmosphere Carbon dioxide added to the air by respiration of animals, plants and microorganisms and by the combustion of fossil fuels. What about organisms that died in anaerobic conditions, out of reach of sapribionts that cause decay? In time they formed coal, oil and other fossil fuels, and contributes to the huge rise in CO 2 levels over the last 50 years in particular! Photosynthesis takes place on such a large scale that it re-uses, on a daily basis, as much carbon dioxide that is released. The Carbon Cycle: THE CARBON CYCLE LABELLING THE CARBON CYCLE FIGURE Burning CO 2 in atmosphere 3 Cellular respiration Photosynthesis 1 Wood and fossil fuels Higher-level consumers Primary consumers Plants, algae, cyanobacteria 2 Decomposition Decomposers (soil microbes) 4 Wastes; death Detritus Plant litter; death 10

11 THE NITROGEN CYCLE The nitrogen cycle is the circulation of nitrogen in the environment as a result of the activity of living organisms and lightning. Human activities also affect the cycle. Nitrogen makes up about 78% of the Earth s atmosphere. During the cycle it is converted from its inert atmospheric molecular form (N 2 ) into a form that can be used in biological processes. Nitrogen is a vital component of every living organism (part of DNA, proteins, chlorophyll). It is only in the form of nitrates that nitrogen can enter food chains. Plants absorb nitrates dissolved in water via their roots. The Nitrogen Cycle: Nitrogen is needed to make amino acids, proteins and nucleic acids. Animals and plants are unable to use nitrogen gas (N 2 ), but instead plants take in nitrogen via nitrates in solution through their roots. This nitrogen is transferred through the food chain and any bodies must be decomposed in order to release these minerals back into the soil! Bacteria are the key organisms involved in this process. FIGURE The Nitrogen Cycle: N 2 in atmosphere The main processes involved in the release of minerals are: 8 Denitrifying bacteria Nitrifying bacteria NO 3 in soil Plant Animal 6 Death; wastes Detritus 7 Decomposers NH 4 in soil 2 1 Nitrogen-fixing bacteria in root nodules Free-living nitrogen-fixing bacteria PUTREFACTION bacteria, and fungi, decompose dead plants and animals, faeces and urine into ammonium ions. This process is also called ammonification. NITRIFICATION the ammonia formed in putrefaction is converted by nitrification via nitrates to nitrates. Various bacteria are involved. For example, ammonia is converted to nitrate by Nitrosomonas and nitrate to nitrate by Nitrobacter. These bacteria require aerobic conditions. The Nitrogen Cycle: The main processes involved in the release of minerals are: The Nitrogen Cycle: Human activities can improve the circulation of nitrogen. NITROGEN FIXATION atmospheric nitrogen can be converted directly into nitrogen compounds by nitrogen fixing bacteria. Free living nitrogen fixing bacteria include Azotobacter. These account for most of the nitrogen fixation. There are also symbiotic nitrogen fixing bacteria, Rhizobium, found in the root nodules of legumes (peas, beans and clover). DENITRIFICATION nitrogen is lost from ecosystems by denitrification. This is a particular problem in waterlogged soils with anaerobic conditions where anaerobic bacteria, such as Pseudomonas, can reduce nitrates and ammonium ions back to nitrogen. By fixing atmospheric nitrogen artificially using chemical processes that convert it to fertilizers. Large amounts of animal waste from stock rearing is used as manure. Sewage disposal boosts organic nitrogen supplies. Microorganisms can be used for making compost and silage. Farming practices such as: Planting fields of clover to encourage nitrogen fixation (CROP ROTATION). Draining land and reducing anaerobic conditions. Ploughing fields in order to improve aeration of the soil. These last two activities ensure that anaerobic bacteria cannot compete with aerobic bacteria thus preventing denitrification. 11

12 FIGURE USE OF FERTILIZERS Farming results in the level of nitrates in the soil being slowly depleted. Fertilizers are used to increase the soil nitrate levels. However, they can have negative effects on the environment. eutrophication leaching causes the overenrichment of water with nutrients, leading to excessive algal growth and reduced oxygen levels reduced species diversity nitrogen-rich soils can favour specific species (e.g. grasses) which may lead to other species being out competed. FIGURE Nitrogen runoff from Midwester n farm fields has been linked to an annual summer dead zone in the Gulf of Mexico. Mississippi River Light blue lines represent rivers draining into the Mississippi River (shown in dark blue) Summer Winter Algae and trash in the lake Taihu, Jiangsu province. Algae on the surface of the Hantszyan River, tributary of the Chang Jiang, after heavy rains, Hebei province. Children swimming in the water overgrown with algae in Cindao, Shandun province. Although the green algae don t do harm to people s health, they affect the aquatic life. 12

13 THE PHOSPHORUS CYCLE FIGURE Organisms require phosphorus as an ingredient of nucleic acids, phospholipids, and ATP. Phosphorus is also required as a mineral component of vertebrate bones and teeth. The phosphorus cycle does not have an atmospheric component. Rock 6 Uplifting of rock 3 Weathering of rock Phosphates Runoff in rock Animals Plants 1 Assimilation 2 Phosphates Detritus in soil (inorganic) 5 Phosphates in solution Solid phosphates 4 Decomposition Decomposers in soil FIGURE THE WATER CYCLE All parts of the biosphere are linked by the global water cycle. Solar heat Water vapor Net movement of water vapor Water vapor Evaporation Evaporation and transpiration Oceans Flow of water from land to sea Surface water and groundwater ACTIVITY: WATER CYCLE LABEL DIAGRAM Solar heat Oceans Water vapor Evaporation Net movement of water vapor Evaporation and Transpiration Water Vapour Surface water and groundwater Flow of water from land to sea VIDEO CLIPS Crash Course in Biogeochemical Cycles - YlCA Nitrogen Cycle 0VPHWbM Crash Course Nitrogen and Phosphorus Cycle Y_8nRs 13

14 HOMEWORK Complete Mastering Biology Activities in Study Notes Mastering Biology Assignment Topic 26 and 27 14