Producers and Consumers: the Living Components of Ecosystems BASIC ECOSYSTEM STRUCTURE Biotic vs. Abiotic Producers, autotrophs … TROPH = EATING/FEEDING Photosynthesis: You must know this reaction CO 2 + H 2 O + sunlight → glucose + oxygen Chemosynthesis Consumers, heterotrophs Decomposers

Energy Flows Through Ecosystems in Food Chains and Food Webs Food chain Movement of energy and nutrients from one trophic level to the next … TROPHIC = EATING/FEEDING FIG 3.13 Food web Network of interconnected food chains FIG 3.14

Usable Energy Decreases with Each Link in a Food Chain or Web Pyramid of energy flow 90% of energy lost with each transfer … AS HEAT Less chemical energy for higher trophic levels FIG 3.15

Some Ecosystems Produce Plant Matter Faster Than Others Do FIG 3.16 Gross primary productivity (GPP) Rate at which producers convert solar energy to chemical energy and biomass Kcal/m 2 /yearWHAT IS GROSS INCOME? Net primary productivity (NPP) GPP (above) minus the rate at which producers use energy for aerobic respiration Ecosystems and life zones differ in their NPP WHAT IS NET INCOME?

Estimated Annual Average NPP in Major Life Zones and Ecosystems FIG 3.16 Fig. 3-15, p. 66

Nutrients Cycle in the Biosphere Biogeochemical cycles, nutrient cycles Hydrologic FIG 3.17 Carbon Nitrogen Phosphorus Sulfur Nutrients may remain in a reservoir for a period of time

Water Cycles through the Biosphere Natural renewal of water quality: three major processes Evaporation Precipitation Transpiration Alteration of the hydrologic cycle by humans Withdrawal of large amounts of freshwater at rates faster than nature can replace it Clearing vegetation causing increased runoff Increased flooding when wetlands are drained Special properties of water Solvent, stays liquid, filters UV rays, expands as it freezes, holds lots of heat

Carbon Cycle Depends on Photosynthesis and Respiration Link between photosynthesis in producers and respiration in producers, consumers, and decomposers Additional CO 2 added to the atmosphere Tree clearing Burning of fossil fuels Warms the atmosphere

Fig. 3-19, p. 70 Carbon dioxide in atmosphere Respiration Photosynthesis Animals (consumers) Burning fossil fuels Diffusion Forest fires Plants (producers) Deforestation TransportationRespiration Carbon in plants (producers) Carbon dioxide dissolved in ocean Carbon in animals (consumers) Decomposition Marine food webs Producers, consumers, decomposers Carbon in fossil fuels Carbon in limestone or dolomite sediments Compaction Process Reservoir Pathway affected by humans Natural pathway

Nitrogen Cycles through the Biosphere: Bacteria in Action (1) Nitrogen fixed by lightning Nitrogen fixed by bacteria and cyanobacteria Combine gaseous nitrogen with hydrogen to make ammonia (NH 3 ) and ammonium ions (NH 4 + ) Nitrification Soil bacteria change ammonia and ammonium ions to nitrate ions (NO 3 - ) Denitrification Nitrate ions back to nitrogen gas

Nitrogen Cycles through the Biosphere: Bacteria in Action (2) Human intervention in the nitrogen cycle 1.Additional NO and N 2 O in atmosphere from burning fossil fuels; also causes acid rain 2.N 2 O to atmosphere from bacteria acting on fertilizers and manure 3.Destruction of forest, grasslands, and wetlands 4.Add excess nitrates to bodies of water 5.Remove nitrogen from topsoil

Nitrogen Cycle in a Terrestrial Ecosystem with Major Harmful Human Impacts Fig. 3-20, p. 71

Process Nitrogen in atmosphere Denitrification by bacteria Reservoir Nitrification by bacteria Pathway affected by humans Natural pathway Nitrogen in animals (consumers) Nitrogen oxides from burning fuel and using inorganic fertilizers Volcanic activity Electrical storms Nitrogen in plants (producers) Decomposition Nitrates from fertilizer runoff and decomposition Uptake by plants Nitrate in soil Nitrogen loss to deep ocean sediments Nitrogen in ocean sediments Bacteria Ammonia in soil

Human Input of Nitrogen into the Environment Supplement 9, Fig 16

Phosphorus Cycles through the Biosphere Cycles through water, the earth’s crust, and living organisms Limiting factor for plant growth Impact of human activities 1.Clearing forests 2.Removing large amounts of phosphate from the earth to make fertilizers 3.Erosion leaches phosphates into streams

Phosphorus Cycle with Major Harmful Human Impacts Fig. 3-21, p. 73

Process Reservoir Pathway affected by humans Natural pathway Phosphates in sewage Phosphates in fertilizer Plate tectonics Phosphates in mining waste Runoff Sea birds Runoff Phosphate in rock (fossil bones, guano) Erosion Ocean food webs Animals (consumers) Phosphate dissolved in water Phosphate in shallow ocean sediments Phosphate in deep ocean sediments Plants (producers) Bacteria

Sulfur Cycles through the Biosphere Sulfur found in organisms, ocean sediments, soil, rocks, and fossil fuels SO 2 in the atmosphere H 2 SO 4 and SO 4 - Human activities affect the sulfur cycle Burn sulfur-containing coal and oil Refine sulfur-containing petroleum Convert sulfur-containing metallic mineral ores

Natural Capital: Sulfur Cycle with Major Harmful Impacts of Human Activities Fig. 3-22, p. 74

Sulfur dioxide in atmosphere Sulfuric acid and Sulfate deposited as acid rain Smelting Burning coal Refining fossil fuels Dimethyl sulfide a bacteria byproduct Sulfur in animals (consumers) Sulfur in plants (producers) Mining and extraction Uptake by plants Sulfur in ocean sediments Decay Process Sulfur in soil, rock and fossil fuels Reservoir Pathway affected by humans Natural pathway

Three Big Ideas 1.Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity. 2.Some organisms produce the nutrients they need, others survive by consuming other organisms, and some recycle nutrients back to producer organisms. 3.Human activities are altering the flow of energy through food chains and webs and the cycling of nutrients within ecosystems and the biosphere.