Presentation on theme: "Ecosystems Chapter 30. Ecosystem An array of organisms and their physical environment, interconnected through a one-way flow of energy and cycling of."— Presentation transcript:
Ecosystems Chapter 30
Ecosystem An array of organisms and their physical environment, interconnected through a one-way flow of energy and cycling of raw materials
Modes of Nutrition Photoautotrophs –Capture sunlight or chemical energy –Primary producers Heterotrophs –Extract energy from other organisms or organic wastes –Consumers, decomposers, detritivores
Simple Ecosystem Model Energy input from sun Nutrient Cycling Producers Autotrophs (plants and other self-feeding organisms) Consumers Heterotrophs (animals, most fungi, many protists, many bacteria) Energy output (mainly metabolic heat)
The role of organisms in an ecosystem Simple Ecosystem Model
marsh hawk crow upland sandpiper garter snake frog spider weaselbadgercoyote ground squirrelpocket gopherprairie vole sparrow earthworms, insects First Trophic Level Second Trophic Level Higher Trophic Levels Connections in a tallgrass prairie food web grasses, composites Fig. 30-4, p.529
Which statement about ecosystems is false? 1.energy flows in a cycle between producers and consumers 2.nutrients are recycled by passing from producers to consumers and back again via decomposers 3.in most ecosystems, energy flow begins with the capture of solar energy by photosynthesizers 4.heterotrophs include bacteria and fungi
Rain-forest food web Rain Forest
Energy Losses Energy transfers are never 100% efficient Some energy is lost at each step Limits number of trophic levels in an ecosystem
Two Types of Food Webs Producers (photosynthesizers) Energy Input: herbivores carnivores decomposers detritivores energy in organic wastes, remains Energy Output energy losses as metabolic heat and as net export from ecosystem Producers (photosynthesizers) decomposers detritivores Transfers: Grazing Food Web Detrital Food Web energy in organic wastes, remains energy losses as metabolic heat and as net export from ecosystem
Ecological Pyramids Primary producers are bases for successive tiers of consumers Biomass pyramid –Dry weight of all organisms Energy pyramid –Usable energy decreases as it is transferred through ecosystem
Biomass Pyramid Aquatic ecosystem, Silver Springs, Florida Long-term study of a grazing food web 5 decomposers, detritivores (bacteria, crayfish) third-level carnivores (gar, large-mouth bass) second-level consumers (fishes, invertebrates) first-level consumers (herbivorous fishes, turtles, invertebrates) primary producers (algae, eelgrass, rooted plants) 809
Energy Pyramid Primary producers trapped about 1.2% of the solar energy that entered the ecosystem 6–16% passed on to next level ,368 20,810 kilocalories/square meter/year top carnivores carnivores herbivores producers decomposers + detritivores = 5,080
Energy flow at Silver Springs Silver Springs Study
Biogeochemical Cycle Flow of an essential substance from the environment to living organisms and back to the environment Main reservoir is in the environment Geologic processes, decomposers aid cycles
Three Categories Hydrologic cycle –Water Atmospheric cycles –Nitrogen and carbon Sedimentary cycles –Phosphorus and other nutrients
Hydrologic Cycle atmosphere ocean land evaporation from ocean 425,000 precipitation into ocean 385,000 evaporation from land plants (evapotranspiration) 71,000 precipitation onto land 111,000 wind-driven water vapor 40,000 surface and groundwater flow 40,000
Watershed A region where precipitation is funneled into a single stream or river
Hubbard Brook Experiment A watershed was experimentally stripped of vegetation All surface water draining from watershed was measured Deforestation caused six-fold increase in calcium content of runoff water
Global Water Crisis Limited amount of fresh water Desalinization is expensive and requires large amounts of energy Aquifers are being depleted Groundwater is contaminated Sewage, agricultural runoff, and industrial chemicals pollute rivers
Aquifer Depletion Hawaiian Islands Alaska
When the Earth's waters move from ocean to atmosphere to land and back again, it is called the _____ cycle. 1.water 2.hydrologic 3.hydrodynamic 4.precipitation
A watershed is _____. 1.a stream or river 2.a river that discharges water directly into the ocean 3.a region where precipitation becomes funneled into a single stream or river 4.a region where precipitation becomes funneled into a reservoir for use in human communities
Carbon Cycle Carbon moves through atmosphere, food webs, ocean, sediments, and rocks Sediments and rocks are the main reservoir Combustion of fossil fuels changes natural balance
diffusion between atmosphere and ocean bicarbonate and carbonate in ocean water marine food webs marine sediments combustion of fossil fuels incorporation into sediments death, sedimentation uplifting sedimentation photosynthesis aerobic respiration Carbon Cycle: Marine
Carbon Cycle: Land photosynthesis aerobic respiration terrestrial rocks soil water land food webs atmosphere peat, fossil fuels combustion of wood deforestation volcanic action death, burial, compaction over geologic time leaching, runoff weathering combustion of fossil fuels
My Carbon Cycle 1. I eat carbohydrate molecules. –These are molecules of fuel which I will “burn”. –Some of the energy released when I burn them will be trapped for me to use. The rest will be lost as heat. 2.The waste products of burned fuel are carbon dioxide and water. I breathe these out. 3.Plants (or other producers) take in carbon dioxide from the atmosphere and use it to make carbohydrate.
According to the last slide, why do I eat carbohydrates? 1.Because they taste good. 2.Because they contain lots of vitamins. 3.Because they contain lots of energy. 4.Because they are low in calories.
Energy saved from burning up my fuel is saved in the form of : 1.Muscle 2.ATP 3.Fat 4.Heat
The only reason I need to breathe in oxygen is : 1.I need oxygen to “burn” fuel molecules. 2.All living things need oxygen. 3.Oxygen + carbon = carbon dioxide. 4.Oxygen is corrosive.
Breathing out : 1.Helps me regulate my body temperature. 2.Gets rid of excess fuel molecules. 3.Burns extra calories. 4.Gets rid of the waste products of burned fuel.
The carbon in the plants I eat comes from : 1.The atmosphere. 2.The food they eat. 3.The soil. 4.Water.
The carbon in the steak I eat comes from : 1.Supplements in animal feed. 2.Vitamins. 3.The cow’s drinking water. 4.The plants eaten by the cow.
Greenhouse Effect Greenhouse gases impede escape of heat from Earth’s surface
Global Warming Long-term increase in temperature of Earth’s lower atmosphere
Carbon Dioxide Increase Carbon dioxide levels fluctuate seasonally Average level is steadily increasing Burning of fossil fuels and deforestation are contributing to the increase
Other Greenhouse Gases CFCs: synthetic gases used in plastics and in refrigeration Methane: released by natural gas production, livestock Nitrous oxide: released by bacteria, fertilizers, and animal wastes
Greenhouse Gases Increasing
Table 30-1, p.537
Nitrogen Cycle Nitrogen is used in amino acids and nucleic acids Main reservoir is nitrogen gas in the atmosphere Nitrogen gas can’t enter food web
Fig , p.538
Nitrogen Fixation Plants cannot use nitrogen gas Nitrogen-fixing bacteria convert nitrogen gas into ammonia (NH 3 ) Ammonia and ammonium can be taken up by plants
Air Pollution Effects of nitrogen oxides released by burning fossil fuels