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Transcript
Chapter 4: Ecosystems: Components, Energy Flow and Matter Cycling I. What is Ecology? • The Study of how Organisms interact with one another… and • How they interact with their non-living environment Organization on the Planet • Ecosystem Organization: 1. Organism: • Any Living thing 2. Population: • Group of interacting Individuals of the same species Biosphere Ecosystems Communities Populations Organisms Fig. 4.2, p. 72 3. Community: • Populations of all the different species occupy a particular place 4. Ecosystem: • Community of different species interacting with one another 5. Biosphere: • All of the Earth’s Ecosystems II. Biomes and Aquatic Life Systems A. Biomes: Land portion of the biosphere Distinct climate and specific life-forms adapted for life within that climate. Climate - long-term patterns of weather is the primary factor determining the type of life B. Aquatic life zones: Marine and Freshwater Ecosystem Concepts and Components Coastal chaparral and scrub Coastal mountain ranges Sierra Nevada Mountain Desert Coniferous forest Great American Desert Coniferous forest Rocky Mountains 15,000 ft 10,000 ft 5,000 ft Prairie grassland Great Plains Deciduous forest Mississippi River Valley Appalachian Mountains Average annual precipitaion 100-125 cm (40-50 in.) 75-100 cm (30-40 in.) 50-75 cm (20-30 in.) 25-50 cm (10-20 in.) Fig. 4.9, p. 76 below 25 cm (0-10 in.) C. Ecotone • Transitional zone between two ecosystems • A mixture of species found in both ecosystems as well as organisms that are unique to the ecotones. Ecosystem Boundaries: Ecotones Land zone Transition zone Number of species Species in land zone Species in aquatic zone Species in transition zone only Fig. 4.10, p. 77 Aquatic zone III. COMPONENTS OF AN ECOSYSTEM 1. ABIOTIC – • Non-living components (Water, air, nutrients and solar energy) 2. BIOTIC – • Living components (Plants, animals, microorganisms) 1. Abiotic Ecological Factors -Each population within an ecosystem has a RANGE OF TOLERANCE to abiotic factors Lower limit of tolerance Few organisms Abundance of organisms Few organisms No organisms Population size No organisms Upper limit of tolerance Zone of Zone of intolerance physiological stress Low Optimum range Temperature Zone of Zone of physiological stress intolerance High A. Range of Tolerance: Minimum and maximum Range in which physical and chemical variations can be tolerated • Individuals in a population may have different levels of tolerance • Due to genetics, health and age • Most susceptible during juvenile and reproductive stages B. Limiting Factor The one factor that is most important in regulating population size Limiting Factor Principle: Too much or too little of any abiotic factor can limit a population ABIOTIC FACTORS • • • • • • • Sunlight Temperature Precipitation Wind Altitude Fire frequency Soil • Water currents • Dissolved nutrient concentration (O,N,P) • Salinity • Suspended solids 2. Main BIOTIC factors within an ecosystem -All the living organisms sustain their existence by the process of METABOLISM. -2 Options: A. PRODUCERS – AUTOTROPHS B. CONSUMERS - HETEROTROPHS A. AUTOTROPHS -Organisms that have the ability to make their own food PHOTOSYNTHESIS CHEMOSYNTHESIS B. HETEROTROPHS Organisms that have to get their food from other sources. Primary consumer: (herbivore) Secondary/Tertiary consumer: (carnivore) Omnivore: Plants and Animals 3 2 Consumer 1 consumer Producer Detritivores and scavengers: Parts of dead organisms or their wastes Decomposers: Breakdown dead material (recycle) AEROBIC RESPIRATION • Process of using Oxygen to break down glucose ANAEROBIC RESPIRATION • Breaking down Glucose without Oxygen Producers / Consumers The Biotic Components of Ecosystems Producers Heat Consumers Decomposers Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Solar energy Heat Decomposers (bacteria, fungus) Heat Heat Producers (plants) Consumers (herbivores, carnivores) Heat IV. Ecological Niches and Adaptation -NICHE: -The “role” that an organism plays in an ecosystem -HABITAT the actual physical location where a species lives. -Two main types of Niches… A. Generalist B. Specialist A. Generalist Species: • Broad niches Ex: Flies, cockroaches, mice, rats, white-tailed deer, raccoons, channel catfish and humans B. Specialists: •Narrow niches Ex: Spotted Owls, Giant Panda Bear Is it better to be a generalist or a specialist? Benefits to specialists: • If conditions are constant there is fewer competitors Benefits to generalists: • Can adapt easier if the conditions are rapidly changing Generalist Species vs. Specialist Species Number of individuals Niche separation Generalist species with a narrow niche Niche breadth Region of niche overlap Resource use Generalist species with a broad niche Fundamental vs. Realized Niche Fundamental Niche: • Full potential range of conditions Realized Niche: • Occupies part of the fundamental niche to avoid competition V. ENERGY TRANSFER: A. Food Chains, Webs, and Trophic Levels 1. Food Chain – Sequence of organisms, each of which is a food source for the next. *Shows how energy and nutrients move from one organism to another through the ecosystem. 2. Food Web- -A complex network of interconnecting food chains showing the relationship of many organisms within an ecosystem. 3. Energy Pyramid/Trophic Levels- A step in the transfer of energy through an ecosystem The level of a food chain that an organism occupies. ENVIRO ENERGY B. Biomass and Energy Flow Each level contains a certain amount of biomass: The dry weight of all organic matter in an organism. 1.) Only a small % of what is eaten is converted into biomass 2.) The amount of usable energy decreases at each trophic level First Trophic Level Producers (plants) Heat Second Trophic Level Primary consumers (herbivores) Heat Heat Third Trophic Level Secondary consumers (carnivores) Fourth Trophic Level Tertiary consumers (top carnivores) Heat Solar energy Heat Heat Detritvores (decomposers and detritus feeders) Heat FOOD CHAINS AND WEBS Ecological Efficiency: • % of usable energy transferred from level to level • Typically 5-20% Pyramid of Energy Flow Explains why: 1.) So few top carnivores 2.) Why these species are the first to suffer when there is disruption 3.) Why they are vulnerable to extinction Ecological Pyramids Heat Heat Tertiary consumers (human) Decomposers Heat 10 Secondary consumers (perch) 100 1,000 10,000 Usable energy Available at Each tropic level (in kilocalories) Heat Primary consumers (zooplankton) Producers (phytoplankton) Heat Pyramids of Biomass and Numbers • Storage of biomass at each level • Organisms are sorted, dried and weighed • Most land ecosystems have a reduction in biomass at each level • There may be more primary consumers in an open ocean • Photoplankon is small and is eaten as soon as it is produced VI. Primary Productivity of Ecosystems Gross primary productivity (GPP) Net primary productivity (NPP) Estuaries Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland and shrubland Temperate grassland Lakes and streams Continental shelf Open ocean Tundra (arctic and alpine) Desert scrub Extreme desert Fig. 4.25, p. 88 800 1,600 2,400 3,200 4,000 4,800 5,600 6,400 7,200 8,000 8,800 9,600 Average net primary productivity (kcal/m2/yr) Gross Primary Productivity (GPP): Rate that producers convert solar energy into biomass Usually greatest in: • Shallow Waters • Coral Reefs (abundant light, heat and nutrients) • Upwellings (Currents bring up nutrients from the ocean bottoms) Least in: • Deserts • Open ocean Net Primary Productivity: Producers must use some of the total biomass they produce for respiration NPP is what is left as available food. Net Primary Productivity = Energy stored - Energy used (Photosynthesis) - (Respiration) Why Not Use the Most Productive Regions to Feed the Human Population? • Most swamp/marsh foods are not fit for human consumption • Most of the nutrient of a tropical forest are stored in the vegetation • Energy requirements of harvesting food from the oceans are too high • It would deplete vital sources of food for other forms of life and alter the food webs How much of the Worlds Net Biomass Do we Use? • Humans have taken over a degraded 73% of the Earth’s land surface • Humans use, waste or destroy 40% of the net primary productivity • What may happen if the human population doubles over the next 4050 years?