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Chapter 3 ch 4 in book! Ecosystems: What Are They and How Do They Work? Chapter Overview Questions What is ecology? What basic processes keep us and other organisms alive? What are the major components of an ecosystem? What happens to energy in an ecosystem? What are soils and how are they formed? What happens to matter in an ecosystem? How do scientists study ecosystems? Core Case Study: Have You Thanked the Insects Today? Many plant species depend on insects for pollination. Insect can control other pest insects by eating them Figure 3-1 Core Case Study: Have You Thanked the Insects Today? …if all insects disappeared, humanity probably could not last more than a few months [E.O. Wilson, Biodiversity expert]. Insect’s role in nature is part of the larger biological community in which they live. THE NATURE OF ECOLOGY Ecology is a study of connections in nature. How organisms interact with one another and with their nonliving environment. Figure 3-2 Other animals 281,000 Known species 1,412,000 Insects 751,000 Fungi 69,000 Prokaryotes 4,800 Plants 248,400 Protists 57,700 Fig. 3-3, p. 52 Case Study: Which Species Run the World? Multitudes of tiny microbes such as bacteria, protozoa, fungi, and yeast help keep us alive. Harmful microbes are the minority. Soil bacteria convert nitrogen gas to a usable form for plants. They help produce foods (bread, cheese, yogurt, beer, wine). 90% of all living mass. Helps purify water, provide oxygen, breakdown waste. Lives beneficially in your body (intestines, nose). Universe Galaxies Solar systems Biosphere Planets Earth Biosphere Ecosystems Ecosystems Communities Populations Realm of ecology Organisms Organ systems Communities Organs Tissues Cells Populations Protoplasm Molecules Atoms Organisms Subatomic Particles Fig. 3-2, p. 51 Populations, Communities, and Ecosystems Members of a species interact in groups called populations. Populations of different species living and interacting in an area form a community. A community interacting with its physical environment of matter and energy is an ecosystem. Populations A population is a group of interacting individuals of the same species occupying a specific area. The space an individual or population normally occupies is its habitat. Figure 3-4 Populations Genetic diversity In most natural populations individuals vary slightly in their genetic makeup. Figure 3-5 THE EARTH’S LIFE SUPPORT SYSTEMS The biosphere consists of several physical layers that contain: Air Water Soil Minerals Life “Bio” means life, so the biosphere is anywhere on this planet we find life. Figure 3-6 Oceanic Crust Atmosphere Vegetation Biosphere and animals Soil Crust Rock Continental Crust Lithosphere Upper mantle Asthenosphere Lower mantle Core Mantle Crust (soil and rock) Biosphere Hydrosphere (living and dead (water) organisms) Lithosphere Atmosphere (crust, top of upper mantle) (air) Fig. 3-6, p. 54 Biosphere Atmosphere • • – Membrane of air around the planet. several layers that vary in temperature and composition78% nitrogen, 21% oxygen Stratosphere is one layer: lower portion contains ozone to filter out most of the sun’s harmful UV radiation. – All the earth’s water: liquid, ice, water vapor Hydrosphere • includes aquifers, groundwater, glaciers, etc. Lithosphere The earth’s crust and upper mantle. What Sustains Life on Earth? Solar energy, the cycling of matter, and gravity sustain all Earth’s life. Biosphere Carbon cycle Phosphorus cycle Nitrogen cycle Water cycle Oxygen cycle Heat in the environment Heat Heat Heat Fig. 3-7, p. 55 What Happens to Solar Energy Reaching the Earth? Solar energy flowing through the biosphere warms the atmosphere, evaporates and recycles water, generates winds and supports plant growth. Figure 3-8 Solar radiation Energy in = Energy out Reflected by atmosphere (34% ) UV radiation Absorbed by ozone Visible Light Absorbed by the earth Radiated by atmosphere as heat (66%) Lower Stratosphere (ozone layer) Troposphere Greenhouse effect Heat Heat radiated by the earth Fig. 3-8, p. 55 ECOSYSTEM COMPONENTS Life exists on land systems called biomes and in freshwater and ocean aquatic life zones. Average annual precipitation 100–125 cm (40–50 in.) 75–100 cm (30–40 in.) 50–75 cm (20–30 in.) 25–50 cm (10–20 in.) below 25 cm (0–10 in.) 4,600 m (15,000 ft.) 3,000 m (10,000 ft.) 1,500 m (5,000 ft.) Coastal mountain ranges Sierra Nevada Mountains Great American Desert Coastal chaparral Coniferous and scrub forest Rocky Mountains Desert Great Plains Coniferous forest Mississippi River Valley Prairie grassland Appalachian Mountains Deciduous forest Fig. 3-9, p. 56 Nonliving and Living Components of Ecosystems Ecosystems consist of nonliving (abiotic) and living (biotic) components. Figure 3-10 Factors That Limit Population Growth Availability of matter and energy resources can limit the number of organisms in a population. Figure 3-11 Factors That Limit Population Growth The physical conditions of the environment can limit the distribution of a species. Figure 3-12 Producers: Basic Source of All Food Most producers capture sunlight to produce carbohydrates by photosynthesis: Photosynthesis: A Closer Look Chlorophyll molecules in the chloroplasts of plant cells absorb solar energy. This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars and oxygen. Figure 3-A Producers: Basic Source of All Food Chemosynthesis: Some organisms such as deep ocean bacteria draw energy from hydrothermal vents and produce carbohydrates from hydrogen sulfide (H2S) gas . Consumers: Eating and Recycling to Survive Consumers (heterotrophs) get their food by eating or breaking down all or parts of other organisms or their remains. Herbivores • Primary consumers that eat producers Carnivores • Primary consumers eat primary consumers • Third and higher level consumers: carnivores that eat carnivores. Omnivores • Feed on both plant and animals. Decomposers and Detritivores Decomposers: Recycle nutrients in ecosystems. Detritivores: Insects or other scavengers that feed on wastes or dead bodies. Figure 3-13 Aerobic and Anaerobic Respiration: Getting Energy for Survival Organisms break down carbohydrates and other organic compounds in their cells to obtain the energy they need. This is usually done through aerobic respiration. The opposite of photosynthesis Aerobic and Anaerobic Respiration: Getting Energy for Survival Anaerobic respiration or fermentation: Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen. The end products vary based on the chemical reaction: • • • • Methane gas Ethyl alcohol Acetic acid Hydrogen sulfide Two Secrets of Survival: Energy Flow and Matter Recycle An ecosystem survives by a combination of energy flow and matter recycling. Figure 3-14 BIODIVERSITY Figure 3-15 Biodiversity Loss and Species Extinction: Remember HIPPO H for habitat destruction and degradation I for invasive species P for pollution P for human population growth O for overexploitation Why Should We Care About Biodiversity? Biodiversity provides us with: Natural Resources (food water, wood, energy, and medicines) Natural Services (air and water purification, soil fertility, waste disposal, pest control) Aesthetic pleasure Solutions Goals, strategies and tactics for protecting biodiversity. Figure 3-16 ENERGY FLOW IN ECOSYSTEMS Food chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem. Figure 3-17 Food Webs Trophic levels are interconnected within a more complicated food web. Figure 3-18 Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web. In Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs Ecological efficiency: percentage of useable energy transferred as biomass from one trophic level to the next. Heat Tertiary consumers (human) Heat Decomposers Heat 10 Secondary consumers (perch) Heat 100 1,000 Primary consumers (zooplankton) Heat 10,000 Producers Usable energy (phytoplankton) Available at Each tropic level (in kilocalories) Fig. 3-19, p. 66 Productivity of Producers: The Rate Is Crucial Gross primary production (GPP) Rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass. Figure 3-20 Net Primary Production (NPP) NPP = GPP – R Rate at which producers use photosynthesis to store energy minus rate at which they use some of this energy through respiration (R). Figure 3-21 What are nature’s three most productive and three least productive systems? Figure 3-22