Workshop on Decomposition and Global Carbon Dynamics

1. An introduction to decomposition and soil and global carbon dynamicsA workshop to develop ideas for using decomposition to teach science standards Rich Conant Natural Resource Ecology Laboratory and School of Global Environmental Sustainability Colorado State University

2. Draft agenda 9:00 – carbon cycle, decomposition background 10:00 – break 10:15 – update on science standards 10:30 – 11:30 questions/discussion 11:30 – 12:00 report-out / discussion 12:00 – 12:30 - lunch 12:30 – 3:30 brainstorm teaching ideas, address challenges, create lesson plans, seize opportunity for clarification while experts are here

3. Understanding the carbon cycle • Carbon cycle science and climate change are important and will continue to be important. • Decisions about carbon management will affect all aspects of our students lives. • People have misconceptions: ideas that are scientifically incorrect • Understanding a few fundamental truths are important for informed decisions.

4. Scientific misconceptions • Example: explaining combustion of octane in gasoline • Combustion converts matter into energy • The pollutants in car exhaust come from the gasoline • Example: source of mass in plants. • Mass comes from the soil • Mass comes from the water

5. Tracing Matter and Energy • Students consistently have matter and energy appearing or disappearing, especially processes in which gases are converted to solids or liquids, or vice versa: • Combustion • Photosynthesis (plant growth) • Cellular respiration (animal weight loss, decay) • They commonly use energy as a “fudge factor”

6. Discourses as “Tool Kits” • Most K-12 students and many adults: Dependent on informal discourse; scientific discourse is abstract, technical, incomprehensible • College science majors: Scientific discourse is thin veneer on informal reasoning about the world • Scientists: Can choose among discourses as the occasion demands; scientific discourse as default

7. Example Question: Oxidation • Gasoline is mostly a mixture of hydrocarbons such as octane: C8H18. Decide whether each of the following statements is true or false about what happens to the atoms in a molecule of octane when it burns. CH + O2 CO2 + H2O

8. What Do People Understand? • Students Taking Pilot Test on Carbon-transforming processes • Science majors taking initial cell biology course at Michigan State University • College chemistry is prerequisite for course • 23 students answered this question on first day of class

9. True or False • Some of the atoms in the octane are incorporated into carbon dioxide in the air. • True is scientific answer • True is informal answer • 20/23 answered “true.” CH + O2 CO2 + H2O

10. True or False • Some of the atoms in the octane are incorporated into air pollutants such as ozone or nitric oxide. • False is scientific answer (C and H atoms can’t become N and O atoms). • True is informal answer (One result of cars burning gasoline is air pollutants.) • 16/23 answered “true.” CH + O2 CO2 + H2O

11. True or False • Some of the atoms in the octane are converted into energy that moves the car. • False is scientific answer (C and H atoms can’t be converted to energy). • True is informal answer (energy is a result of gasoline burning). • 15/23 answered “true.” CH + O2 CO2 + H2O

12. What are these fundamental truths? • Energy can come in many forms (e.g., kinetic, chemical, heat, light) and can change from one form to another • Some energy is lost as heat – energy transfer is less than 100% efficient • Energy is transformed within ecosystems, used by organisms, and exits the system • Matter cannot be created or destroyed • Matter can be found in solid, liquid or gas forms, and can change from one to another • True not just for water!

13. High school • Physical science • Energy exists in many forms (mechanical, chemical, electrical, radiant, thermal, and nuclear) that can be quantified and experimentally determined • When energy changes form, it is neither created not destroyed; however, because some is necessarily lost as heat, the amount of energy available to do work decreases • Life Science • Matter tends to be cycled within an ecosystem, while energy is transformed and eventually exits an ecosystem

14. Middle school • 8th grade • Physical Science • There are different forms of energy, and those forms of energy can be changed from one form to another – but total energy is conserved • Distinguish between physical and chemical changes, noting that mass is conserved during any change • 6th grade • Life Science • Organisms interact with each other and their environment in various ways that create a flow of energy and cycling of matter in an ecosystem

15. Goals for this workshop • Learn about the global carbon cycle and decomposition. • Explore carbon cycle/decomposition • Learn about new (draft) state science standards. • Develop lesson plans to use decomposition as a platform for teaching standards related to energy, matter, respiration, and ecosystems. • Develop a partnership for ongoing support.

16. Atmospheric CO2

17. CO2 concentrations are increasing: • Human activities are driving increases in atmospheric CO2

18. CO2 Global Carbon Cycle Atmosphere800 Gt C+3-5 per year ~10 Gt C

19. CO2 Global Carbon Cycle Atmosphere800 Gt C+3-5 per year 57Photosynthesis ~10 Gt C

20. Photosynthesis

21. C6H12O6 + O2 CO2 + H2O

22. CO2 Global Carbon Cycle Atmosphere800 Gt C+3-5 per year 57Photosynthesis 55Respiration & Decomposition ~10 Gt C

23. 1 2 3 Atmospheric CO2 over time (IPCC FAR WGI SPM)

24. CO2 Global Carbon Cycle Atmosphere800 Gt C+3-5 per year 57Photosynthesis 55Respiration & Decomposition ~10 Gt C

25. CO2 Global Carbon Cycle Atmosphere800 Gt C+3-5 per year CO2 ~10 Gt C Land Biota630

26. CO2 concentrations are increasing: • Human activities are driving increases in atmospheric CO2

27. 1975 Rondonia State, Brazil Forest

28. 2001 Rondonia State, Brazil Forest

29. 2001 Rondonia State, Brazil Forest

30. 2001 Rondonia State, Brazil Forest

31. CO2 CO2 CO2 Global Carbon Cycle Atmosphere800 Gt C+3-5 per year ~10 Gt C Land Biota630 Soil and Detritus 1600

32. CO2 concentrations are increasing: • Human activities are driving increases in atmospheric CO2

34. Ten interesting things about decomposition • It makes an major contribution to the global carbon cycle.

35. How does matter change from litter to soil organic matter? CO2 C6H12O6 + O2 CO2 + H2O Fragmentation Chemical alteration Mineral nutrients

36. Ten interesting things about decomposition • It makes an major contribution to the global carbon cycle. • It makes mineral nutrients available to plants.

37. Terrestrial carbon feedbacks

38. Ten interesting things about decomposition • It makes an major contribution to the global carbon cycle. • It makes mineral nutrients available to plants.

39. Fragmentation • Fresh litter is protected from microbial attack • Bark, epidermis or skin on exterior • Plant cells protected by lignin in cell walls • Carried out mainly by soil animals • Increases surface area for microbial attack • Important in aquatic and terrestrial ecosystems

40. Chemical alteration • Breaks down organic matter to CO2 and nutrients • Forms complex recalcitrant compounds • Reaction rates differ as a function of temperature, moisture, etc.

41. Who are the decomposers and why do the do it?

42. Bacteria • Grow rapidly • Specialize on labile substrates • Some bacteria function anaerobically • Dependent on substrates that diffuse to bacterium • Diffusion gradient caused by • Production of soluble substrates (enzymes) • Uptake of substrates by bacterium

43. Fungi • Accounts for most decomposition in aerobic environments • 60-90% of microbial biomass in forests • About half of microbial biomass in grasslands • Broad enzymatic capability • Cell walls (lignin, cellulose, hemicellulose) • Fungi are main lignin degraders • Cell contents (proteins, sugars, lipids)

44. Fungi (contd) • Composed of long networks of hyphae • Can transport metabolites through hyphae • Surface litter (import nitrogen from soil) • Wood degraders (import nitrogen from soil)

45. Soil animals: microfauna • Protozoans (ciliates, amoebae) • Aquatic, mobile • Bacterial predators (phagocytosis) • Rhizosphere specialists • Nematodes (many trophic roles) • Extremely abundant • Often eat as much as aboveground grazers • Mites (many trophic roles)

46. Soil animals: mesofauna • Animals with greatest effect on decomposition • Fragment litter • Ingest litter particles and digest the microbial jam • Collembolans are important mesofauna in northern soils

47. Soil animals: macrofauna • Earthworms, termites, etc. • Fragment litter or ingest soil • Ecosystem engineers • Mix soil, carry organic matter to depth • Reduce compaction • Create channels for water and roots

48. Soil animals • Account for only 5-10% of soil respiration • Major impacts on decomposition are indirect • Alter soil environment • Graze bacteria and fungi • Excrete nitrogen and phosphorus

49. Who are the decomposers and why do the do it?

50. Who are the decomposers and why do the do it? • Decomposer organisms are subject to natural selection • Decomposition is result of their feeding activity and population dynamics • NOT a community service the carbon cycle • They couldn’t care less about whether their activity promotes nutrient cycling and productivity of ecosystems