Human Energy Systems Unit Activity 4.4: The Seasonal Cycle Carbon: Transformations in Matter and Energy Environmental Literacy Project Michigan State University Human Energy Systems Unit Activity 4.4: The Seasonal Cycle

Explaining the seasonal cycle The Keeling Curve Explaining the seasonal cycle

Watch a video about seasonal changes Amount of plant growth

How does this help explain the Keeling Curve seasonal cycle? February July

Why do carbon dioxide concentrations GO DOWN during the spring and summer? Let's use carbon transforming processes--photosynthesis and cellular respiration--and global carbon pools to explain.

Make predictions Atmosphere Inorganic Carbon Pool Biomass Organic Carbon Pool Atmosphere Fossil Fuels Organic Carbon Pool Soil Organic Carbon Pool Fossil Fuels Soil Carbon

Instructions Begin at one pool. On the poster, write your ideas about where carbon atoms could go after they are in this pool, and what causes them to go there. For example, if you are in the biomass pool, you might write “carbon goes to soil pool” because “leaves fall off a tree and decompose.” Write down as many ideas as you can (it’s ok if they are wrong). Then, move to the next poster. Revise and edit the ideas in the next pool. Keep moving until you return to your original pool.

Fluxes of carbon change during seasons Photosynthesis moves carbon atoms from the atmosphere to biomass. Plants do photosynthesis and grow!! Living things die and begin to decompose. Decomposers do cellular respiration. Plants and animals do cellular respiration. SPRING & SUMMER: Plants are growing Lots of photosynthesis 400 570 560 540 580 550 620 610 530 600 590 470 450 440 430 460 630 510 490 480 520 680 770 760 750 780 790 820 810 800 740 730 670 660 650 420 690 720 710 700 640 500 410 800 670 680 700 660 650 620 630 640 710 730 780 790 390 380 770 760 610 740 750 720 690 410 400 470 480 600 420 430 440 450 490 460 550 500 560 570 590 580 530 540 510 520 Biomass Atmosphere Cellular respiration moves carbon atoms from biomass to the atmosphere. Cellular respiration moves carbon atoms from soil organic carbon to the atmosphere. Death and defecation move carbon atoms from biomass to soil organic carbon 1010 1000 1020 940 970 980 990 960 950 920 900 930 910 Soil Carbon Fossil Fuels

Beginning of spring (April) End of summer (October) Compare: What is the overall movement of carbon atoms among pools during the spring and summer? Beginning of spring (April) End of summer (October) Soil Carbon Atmosphere Fossil Fuels Biomass 800 400 1000 Soil Carbon Atmosphere Fossil Fuels Biomass 900 600 700

Why do carbon dioxide concentrations INCREASE during the fall and winter? Let's use carbon transforming processes--cellular respiration--and global carbon pools to explain.

Fluxes of carbon change during seasons Cellular respiration moves carbon atoms from biomass to the atmosphere. Plants and animals still do cellular respiration. Leaves fall and annual plants die and enter the soil pool. Living things die and begin to decompose. FALL & WINTER: Most plants stop growing Less photosynthesis 400 540 530 550 580 520 570 480 470 590 490 500 510 630 670 680 690 700 660 650 610 620 460 640 600 560 410 420 450 430 440 800 730 710 750 720 780 790 700 770 760 740 610 640 630 690 650 600 680 670 660 620 Biomass Atmosphere Cellular respiration moves carbon atoms from soil organic carbon to the atmosphere. Death and defecation move carbon atoms from biomass to soil organic carbon 1000 1040 1020 1030 1010 1060 1100 1090 1080 1070 1050 980 960 970 990 900 950 910 920 940 930 Soil Carbon Fossil Fuels

Beginning of fall (October) Compare: What is the overall movement of carbon atoms among pools during the fall and winter? Beginning of fall (October) End of winter (April) Soil Carbon Atmosphere Fossil Fuels Biomass 600 700 900 Soil Carbon Atmosphere Fossil Fuels Biomass 800 400 1000

Three Questions at the Large-Scale The Carbon Pools Question. Where are the carbon pools in our environment? The Carbon Movement Question: How are carbon atoms cycling among pools? The Energy Question: How does energy flow through Earth systems?