Ecosystems What Are They and How Do They

Ecosystems: What Are They and How Do They Work? Chapter 3

Importance of Insects n Pollination n Pest control n Important roles in biological community Fig. 4 -A, p. 64

Nature of Ecology n What is ecology? n Organisms n Cells n Species n Microbes rule! Fig. 3 -2, p. 37

Populations, Communities, and Ecosystems n Populations n Genetic diversity n Biological community n Ecosystems n Biosphere

Population of Monarch Butterflies Fig. 4 -3, p. 63

Genetic Diversity in One Snail Species Fig. 4 -3, p. 63

What Sustains Life on Earth? n Troposphere n Stratosphere n Hydrosphere n Lithosphere n Biosphere Fig. 3 -2, p. 42

Earth’s Life-Support Systems n One way flow of high-quality energy n Cycling of matter n Gravity Fig. 3 -6, p. 39

Flow of Solar Energy to and from the Earth n Greenhouse gases n Greenhouse effect Fig. 3 -3, p. 42

Flow of Solar Energy to and from the Earth Solar radiation Energy in = Energy out Reflected by atmosphere (34%) UV radiation Absorbed by ozone Radiated by atmosphere as heat (66%) Lower Stratosphere (ozone layer) Visible light Troposphere Greenhouse effect Heat Absorbed by the earth Heat radiated by the earth Fig. 3 -3, p. 42

Why is the Earth so Favorable for Life? n Liquid water n Temperature n Gravity n Atmosphere

Ecosystem Components n Biomes n Aquatic life zones n Freshwater life zones n Ocean or marine life zones n Abiotic and biotic components n Range of tolerance n Law of tolerance

Major Biomes 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 Coastal chaparral and scrub Sierra Nevada Mountains Great American Desert Coniferous forest Rocky Mountains Desert Great Plains Coniferous forest Mississippi River Valley Prairie grassland Appalachian Mountains Deciduous forest Fig. 3 -8, p. 41

Major Components of Freshwater Ecosystems Sun Producers (rooted plants) Producers (phytoplankton) Primary consumers (zooplankton) Secondary consumers (fish) Tertiary consumers (turtles) Dissolved chemicals Sediment Decomposers (bacteria and fungi) Fig. 3 -9, p. 42

Major Components of a Field Ecosystem Oxygen (O 2) Sun Producer Carbon dioxide (CO 2) Primary consumer (rabbit) Falling leaves Precipitation and twigs Secondary consumer (fox) Producers Soil decomposers Water Soluble mineral nutrients Fig. 3 -10, p. 42

Range of Tolerance Lower limit of tolerance Few organisms Abundance of organisms Few organisms No organisms Population Size No organisms Upper limit of tolerance Zone of intolerance Low Zone of physiological stress Optimum range Temperature Zone of intolerance physiological stress High Fig. 3 -11, p. 43

Factors Limiting Population Growth n Limiting factors n Limiting factor principle n Excess water or water shortages for terrestrial organisms n Excess or lack of soil nutrients n Dissolved oxygen for aquatic organisms n Salinity for aquatic organisms

Major Biological Components of Ecosystems n Producers (autotrophs) n Photosynthesis n Chemosynthesis n Consumers (heterotrophs)

Consumers: Feeding and Respiration n Decomposers n Omnivores n Detritivores n Aerobic respiration

Detritivores Detritus feeders Long-horned beetle holes Bark beetle engraving Carpenter ant galleries Termite and carpenter ant work Decomposers Dry rot fungus Wood reduced to powder Time progression Mushroom Powder broken down by decomposers into plant nutrients in soil Fig. 3 -8, p. 45

Main Structural Components of an Ecosystem Heat Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Heat Solar energy Heat Producers (plants) Decomposers bacteria, fungi) Heat Consumers (herbivores, carnivores) Heat Fig. 3 -9, p. 46

Biodiversity Fig. 3 -14, p. 45

Examples of Biodiversity Fig. 3 -15, p. 46

Food Chains and Food Webs n Food chain n Trophic level n Food web

Model of a Food Chain First Trophic Level Producers (plants) Heat Second Trophic Level Third Trophic Level Fourth Trophic Level Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores) Heat Solar energy Heat Detritivores decomposers and detritus feeders) Heat Fig. 3 -10, p. 47

Food Web in the Antarctic Humans Sperm whale Blue whale Elephant seal Killer whale Crabeater seal Leopard seal Adélie penguins Petrel Emperor penguin Fish Squid Carnivorous plankton Herbivorous zooplankton Krill Phytoplankton Fig. 3 -11, p. 48

Energy Flow in an Ecosystem n Biomass n Ecological efficiency n Pyramid of energy flow

Pyramid of Energy Flow 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) Heat Producers (phytoplankton) Fig. 3 -12, p. 49

Biomass Productivity n Gross primary productivity (GPP) n Net primary productivity (NPP) n NPP and populations

Differences between GPP and NPP Sun is es nth sy oto Ph Respiration Gross primary production Growth and reproduction Energy lost and unavailable to consumers Net primary production (energy available to consumers) Fig. 3 -19, p. 49

Net Primary Productivity in Major Life Zones and Ecosystems Terrestrial Ecosystems Swamps and marshes Tropical rain forest Temperate forest Northern coniferous forest (taiga) Savanna Agricultural land Woodland shrubland Temperate grassland Tundra (arctic and alpine) Desert scrub Extreme desert Aquatic Ecosystems Estuaries Lakes and streams Continental shelf Open ocean 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/m 2/yr) Fig. 3 -13 p. 49

Soils n Origins of soils n Soil horizons: O, A, B, and C n Soil profiles n Infiltration and leaching

Soil Formation and Horizons Oak tree Wood sorrel Lords and ladies Earthworm Fern Dog violet Millipede Honey fungus Mole Grasses and Organic debris small shrubs builds up Moss and Rock fragments lichen O horizon Leaf litter A horizon Topsoil Bedrock B horizon Subsoil Immature soil Regolith Young soil Pseudoscorpion Mite C horizon Parent material Nematode Root system Mature soil Red earth Springtail Fungus mite Bacteria Actinomycetes Fig. 10 -A, p. 209

Soil Profiles from Different Ecosystems Fig. 3 -22, p. 52

Soil Profiles from Different Ecosystems Mosaic of closely packed pebbles, boulders Alkaline, dark, and rich in humus Weak humusmineral mixture Dry, brown to reddish-brown, with variable accumulations of clay, calcium carbonate, and soluble salts Desert Soil (hot, dry climate) Clay, calcium compounds Grassland Soil (semiarid climate) Fig. 3 -22 a, p. 52

Soil Profiles from Different Ecosystems Forest litter leaf mold Tropical Rain Forest Soil (humid, tropical climate) Acidic lightcolored humus Humus-mineral mixture Iron and aluminum compounds mixed with clay Dark brown Firm clay Acid litter and humus Light-colored and acidic Light, grayishbrown, silt loam Deciduous Forest Soil (humid, mild climate) Humus and iron and aluminum compounds Coniferous Forest Soil (humid, cold climate) Fig. 3 -22 b, p. 52

p. H n Acidity or alkalinity of water or water-bearing samples n Scale 0 -14 n Acidic: p. H 0 -6. 9 n Neutral p. H 7. 0 n Alkaline (basic): p. H 7. 1 -14

The p. H Scale Fig. 3 -23, p. 192

Matter Cycling in Ecosystems: Biogeochemical Cycles n Nutrient (biogeochemical) cycles n Hydrologic (water) cycle n Carbon cycle n Nitrogen cycle n Phosphorus cycle n Sulfur cycle

Simplified Hydrologic (Water) Cycle Condensation Rain clouds Transpiration Precipitation to land Transpiration from plants Rapid Surface runoff (rapid) Evaporation From land Precipitation Evaporation From ocean Precipitation to ocean Surface runoff (rapid) Infiltration and percolation Groundwater movement (slow) Ocean storage Fig. 3 -14, p. 51

Human Intervention in the Hydrologic Cycle n Large withdraw of surface and ground waters n Clearing vegetation n Pollution

The Carbon Cycle (Marine) Diffusion between atmosphere and ocean Carbon dioxide dissolved in ocean water photosynthesis Combustion of fossil fuels aerobic respiration Marine food webs Producers, consumers, decomposers, detritivores incorporation death, into sediments sedimentation Marine sediments, including formations with fossil fuels uplifting over geologic time sedimentation Fig. 3 -15 p. 53

The Carbon Cycle (Terrestrial) Atmosphere (most carbon is in carbon dioxide) Combustion of fossil fuels volcanic action Terrestrial rocks weathering photosynthesis aerobic respiration Land food webs Producers, consumers, decomposers, detritivores combustion of wood (for clearing land; or fuel) deforestaion Soil water (dissolved carbon) death, burial, compaction over geologic time Peat, fossil fuels leaching, runoff Fig. 3 -15, p. 53

Human Interference in the Global Carbon Cycle High projection Low projection Fig. 3 -26, p. 56

The Nitrogen Cycle Gaseous Nitrogen (N 2) in Atmosphere Nitrogen Fixation by industry for agriculture Food Webs on Land uptake by autotrophs Fertilizers excretion, death, decomposition uptake by autotrophs Nitrogen Fixation bacteria convert N 2 to ammonia (NH 3); this dissolves to form ammonium (NH 4+) NH 3, NH 4 in Soil loss by leaching + Nitrogenous Wastes, Remains in Soil Ammonification bacteria, fungi convert the residues to NH 3; this dissolves to form NH 4+ 1. Nitrification bacteria convert NH 4+ to nitrite (NO 2–) NO 3– in Soil Denitrification by bacteria 2. Nitrification bacteria convert NO 2– to nitrate (NO 3–) NO 2– in Soil loss by leaching Fig. 3 -16 p. 54

Human Interference in the Global Nitrogen Cycle pr oc e ss es Nitrogen fixation by natural processes n Nitrogen fixationby a um h Fig. 3 -28, p. 58

The Phosphorus Cycle mining Fertilizer Guano excretion agriculture uptake by autotrophs Marine Food Webs uptake by autotrophs Dissolved in Ocean Water leaching, runoff Dissolved in Soil Water, Lakes, Rivers death, decomposition sedimentation Land Food Webs weathering settling out Marine Sediments uplifting over geologic time Rocks Fig. 3 -17, p. 55

The Sulfur Cycle Sulfur trioxide Water Sulfuric acid Acidic fog and precipitation Ammonium sulfate Oxygen Sulfur dioxide Ammonia Hydrogen sulfide Plants Dimethyl sulfide Volcano Animals Industries Ocean Sulfate salts Metallic Sulfide deposits Decaying matter Sulfur Hydrogen sulfide Fig. 3 -18, p. 56

How Do Ecologists Learn about Ecosystems? n Field research n Remote sensing n Geographic information system (GIS) n Laboratory research n Systems analysis

Geographic Information System (GIS) Critical nesting site locations Private owner 1 USDA Forest Service Private owner 2 Topography Forest Wetland Lake Grassland Habitat type Real world Fig. 3 -31, p. 61

Stages of Systems Analysis Systems Measurement Define objectives Identify and inventory variables Obtain baseline data on variables Data Analysis Make statistical analysis of relationships among variables System Modeling Construct mathematical model describing interactions among variables System Simulation System Optimization Determine significant interactions Run the model on a computer, with values entered for different variables Evaluate best ways to achieve objectives. Stepped Art Fig. 3 -32, p. 61

Importance of Baseline Ecological Data n To understand nature, current conditions must be known n Baseline data are lacking n Long-term sustainability