ECOSYSTEMS Chapter 47

Impacts, Issues Video Bye-Bye, Blue Bayou

Ecosystem An association of organisms and their physical environment, interconnected by ongoing flow of energy and a cycling of materials

Modes of Nutrition Autotrophs Capture sunlight or chemical energy Producers Heterotrophs Extract energy from other organisms or organic wastes Consumers, decomposers, detritivores

The role of organisms in an ecosystem Simple Ecosystem Model

energy input from sun nutrient cycling PHOTOAUTOTROPHS (plants, other producers) HETEROTROPHS (consumers, decomposers) energy output (mainly heat)

Consumers Herbivores Carnivores Parasites Omnivores Decomposers Detritivores

Diet of the red fox Consumers

Trophic Levels All the organisms at a trophic level are the same number of steps away from the energy input into the system Producers are closest to the energy input and are the first trophic level

Trophic Levels in Prairie 5th 4th 3rd 2nd 1st Fourth-level consumers (heterotrophs): Top carnivores, parasites, detritivores, decomposers Third-level consumers (heterotrophs): Carnivores, parasites, detritivores, decomposers Second-level consumers (heterotrophs): Carnivores, parasites, detritivores, decomposers First-level consumers (heterotrophs): Herbivores, parasites, detritivores, decomposers Primary producers (autotrophs): Photoautotrophs, chemoautotrophs

Food Chain A straight-line sequence of who eats whom Simple food chains are rare in nature

Food chain Food Chain

Tall-Grass Prairie Food Web earthworms, insects sparrow vole pocket gopher ground squirrel coyote badgerweasel spider frog snake sandpipercrow marsh hawk grasses, composites

Food Web Show how many animals are interconnected by different paths. It also shows how plants and animals are connected in many ways to help them all survive

Rain-forest food web Rain Forest

Energy Losses Energy transfers are never 100 percent efficient Some energy is lost at each step Limits the number of trophic levels in an ecosystem

Food webs Food Webs

Pyramid of Energy Flow Primary producers trapped about 1.2 percent 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 In Silver Springs 20,810 1,679,190 Incoming solar energy not harnessed: 1,679,190 (98.8%) ENERGY INPUT: 1,700,000 kilocalories 20,810 (1.2%) Producers To next trophic level: Energy in organic wastes and remains: Energy losses as metabolic heat & as net export from ecosystem: Herbivores Carnivores Top carnivores Decomposers, detritivores 4, , ,197 2, ,060 ENERGY OUTPUT: Total annual energy flow: 1,700,000 (100%)

All Heat in the End At each trophic level: the bulk of the energy received from the previous level is used in metabolism released as heat energy and lost to the ecosystem Eventually all energy is released as heat

Biogeochemical Cycle The flow of a nutrient from the environment to living organisms and back to the environment Main reservoir for the nutrient is in the environment

geochemical cycle Main nutrient reservoirs in the environment fraction of nutrient available to ecosystem primary producers herbivores, carnivores, parasites detritivores, decomposers Fig , p.852

Three Categories Hydrologic cycle Water Atmospheric cycles Nitrogen and carbon Sedimentary cycles Phosphorus and sulfur

EVAPORATION PRECIPITATION TRANSPIRATION dripping, trickling down along stems falling through to ground interception by plants surface pooling, etc. infiltration of soil moisture in soil seepage, percolation groundwater storage DEEP OUTFLOW overland flow lateral flow base flow STREAM OUTFLOW

Water Use and Scarcity Most of Earth’s water is too salty for human consumption Desalinization is expensive and requires large energy inputs Irrigation of crops is the main use of freshwater

Negative Effects of Irrigation Salinization, mineral buildup in soil Elevation of the water table and waterlogging Depletion of aquifers Underground layer of water bearing permeable rock or unconsolidated materials (gravel, sand, silt or clay) from which groundwater can be extracted Water table

Threats to aquifers Aquifer Problems

Carbon Cycle Carbon moves through the atmosphere and food webs on its way to and from the ocean, sediments, and rocks Sediments and rocks are the main reservoir

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 sedimentation volcanic action death, burial, compaction over geologic time leaching, runoff weathering combustion of fossil fuels

Carbon cycle Carbon Cycle

Carbon in the Oceans Most carbon in the ocean is dissolved carbonate and bicarbonate Ocean currents carry dissolved carbon

Carbon in Atmosphere Atmospheric carbon is mainly carbon dioxide Carbon dioxide is added to atmosphere Aerobic respiration, volcanic action, burning fossil fuels Removed by photosynthesis

Greenhouse effect Greenhouse Effect

Carbon Dioxide Increase Carbon dioxide levels fluctuate seasonally The 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 - produced by termites and bacteria Nitrous oxide - released by bacteria, fertilizers, and animal wastes

Greenhouse gases Greenhouse Gases

Nitrogen Cycle Nitrogen is used in amino acids and nucleic acids Main reservoir is nitrogen gas in the atmosphere

Nitrogen Cycle Nitrogen cycle

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

Ammonification & Nitrification Bacteria and fungi carry out ammonification conversion of nitrogenous wastes to ammonia Nitrifying bacteria convert ammonium to nitrites and nitrates

Nitrogen Loss Nitrogen is often a limiting factor in ecosystems Nitrogen is lost from soils via leaching and runoff Denitrifying bacteria convert nitrates and nitrites to nitrogen gas

Human Effects Humans increase rate of nitrogen loss by clearing forests and grasslands Humans increase nitrogen in water and air by using fertilizers and by burning fossil fuels Too much or too little nitrogen can compromise plant health

guano fertilizer terrestrial rocks land food webs dissolved in seawater marine food webs marine sediments excretion weathering mining agriculture uptake by producers death, decomposition sedimentation settling out leaching, runoff weathering uplifting over geologic time dissolved in soil water, lakes, rivers uptake by autotrophs death, decomposition Phosphorus cycle

Deforestation Effect of air pollution in forests

Phosphorus Cycle Phosphorus is part of phospholipids and all nucleotides It is the most prevalent limiting factor in ecosystems Main reservoir is Earth’s crust; no gaseous phase

Phosphorus Cycle GUANO FERTILIZER TERRESTRIAL ROCKS LAND FOOD WEBS DISSOLVED IN OCEAN WATER MARINE FOOD WEBS MARINE SEDIMENTS excretion weathering mining agriculture uptake by autotrophs death, decomposition sedimentation settling out leaching, runoff weathering uplifting over geologic time DISSOLVED IN SOILWATER, LAKES, RIVERS uptake by autotrophs death, decomposition Figure 47-27, Page 862

Phosphorus Cycle Phosphorus cycle