1. Chapter 3 Part II: Matter Cycling in Ecosystems Unit III: Ecosystem Ecology

2. I. Nutrient Cycles BIOGEOCHEMICAL CYCLES: natural processes that involve the flow of nutrients through ecosystems: atmosphere, hydrosphere, lithosphere, organisms. The BIG SIX Carbon, Nitrogen, Oxygen, Hydrogen, Sulfur, Phosphorus-all critical to life. Each cycle takes various pathways and has various reservoirs and varies in time depending on chem reactivity and whether or not element is in gaseous phase. Can be disturbed by humans. Fig. 4–6 © Brooks/Cole Publishing Company / ITP

3. II. Carbon Cycle-Why it is Important The most important element in living organisms: *20% body weight; basis of organic molecules that form membranes, tissues, proteins, carbs, energy Important to the climate system (nature’s thermostat) which sets the background for our environment: *carbon dioxide (CO 2 ) and methane (CH 4 ) are greenhouse gases which help determine global temperatures

4. Carbon Cycle Fig. 4–23 © Brooks/Cole Publishing Company / ITP D:\Media\LITE_15e\PowerLectures\chapter3\Animations\carbon_cycle.html

6. Processes That Drive the Carbon Cycle Photosynthesis Respiration Exchange Sedimentation Burial Extraction Combustion

7. Carbon Exchange between atmosphere and ocean Oceans: CO 2 dissolved in water, marine sediments, marine organisms. When CO 2 enters the ocean, it participates in a series of reactions Solution: CO 2 (atmospheric) ⇌ CO 2 (dissolved) Conversion to carbonic acid:CO 2 (dissolved) + H 2 O ⇌ H 2 CO 3 Ionization:H 2 CO 3 ⇌ H + + HCO 3 − (bicarbonate ion) HCO 3 − ⇌ H + + CO 3 2- (carbonate ion) http://www.whoi.edu/home/oceanus_images/ries/calcifi cation.html

8. Sedimentation and Burial In the oceans, bicarbonate can combine with calcium to form limestone (calcium carbonate, CaCO 3, with silica), which precipitates to the ocean floor and form limestone via sedimentation. Slow, but has accumulated much C over time! A small fraction of organic carbon in dead biomass is buried in ocean sediments before it can be decomposed-fossilizes-fossil fuels

9. Extraction, Combustion and other Human Influences Removal of fossil fuels from earth Burning of fossils fuels Equation CH 4 + 2O 2 CO 2 +2 H 2 O In absence of human disturbance the exchange of C between Earth surface and atmosphere in a steady state. Large Scale Deforestation without Reforestation Carbon Sinks Oceans, Land Plants, Sedimentary Rocks, Fossil fuels in lithosphere Old Carbon vs. New Carbon

10. III. Nitrogen Cycle Role of Nitrogen: building block of various essential organic molecules – especially proteins & nucleic acids; Plant chlorophyll-photosynthesis- requires nitrogen limiting nutrient in many ecosystems – typically, addition of N leads to increased productivity. © Brooks/Cole Publishing Company / ITP

11. Nitrogen Cycle Fig. 4–24 © Brooks/Cole Publishing Company / ITP D:\Media\LITE_15e\PowerLectures\chapter3\Animations\nitrogen_cycle_v2.html

13. © Brooks/Cole Publishing Company / ITP Nitrogen Cycle Processes Nitrogen Fixation: N 2 NH 3 /NH 4 + Nitrification: NH 3 /NH 4 + NO 2 - /NO 3 - Assimilation: NO 2 - /NO 3 - organic compounds (proteins) Ammonification: organic NH 3 Dentrification: NO 3 - N 2

14. Nitrogen Cycle Sinks: Atmosphere, Biomass, Continental Shelf Human Influences: Burn fuels at high temps. Releases NO 2 (NO x ) –acid rain Commercial fertilizers and livestock waste Release N stored in plants and soils as gaseous compounds through destruction of forest, grasslands and wetlands add excess N to aquatic systems-runoff- eutrophication © Brooks/Cole Publishing Company / ITP

15. IV. Phosphorus Cycle Role of Phosphorus: essential nutrient for plants & animals – DNA, other nucleic acids limiting nutrient in many ecosystems – addition of P increases productivity, especially for freshwater aquatic systems. Phosphorus Cycled slowly-no gaseous phase. Water-Crust-Living organisms Sinks: Sedimentary and Igneous Rock, Ocean sediments Human Effects: Remove to make fertilizer, reduce when we cut tropical forests, disrupt aquatic systems with runoff, detergents © Brooks/Cole Publishing Company / ITP

16. Phosphorus Cycle Fig. 4–25 © Brooks/Cole Publishing Company / ITP D:\Media\LITE_15e\PowerLectures\chapter3\Animations\phos_anim.htmlMedia\LITE_15e\PowerLectures\chapter3\Animations\phos_anim.html

18. Phosphorus Cycle main processes: weathering: P slowly released from rock or soil minerals as phosphate (P0 4 3- ), which dissolves in H 2 0 & is readily leached; uptake: by plants to form organic phosphates; movement through food web; break down of organic forms: to phosphate (P0 4 3- ) by decomposers; leaching: P0 4 3- from soil; burial in ocean sediments. © Brooks/Cole Publishing Company / ITP

19. V. Sulfur Cycle Stored in underground rocks, minerals and soil Plants take up sulfur as sulfate-cycles through food web H 2 S organic matter in swamps and bogs. SO 2 enters atmosphere from volcanoes SO X (SO 2 and SO 3 ) lead to acid precipitation. Humans Effect on Sulfur :\Media\LITE_15e\PowerLectures\chapter3\Anim ations\sulfur_cycle.html :\Media\LITE_15e\PowerLectures\chapter3\Anim ations\sulfur_cycle.html

21. Nutrient Cycling & Sustainability ecosystems tend toward equilibrium with respect to energy flow & nutrient cycling; may appear self– contained; “immature” natural ecosytems -- major shifts in energy flow & nutrient cycling; ecosystems not self-contained -- considerable exchange of water & nutrients of ecosystems with adjacent ecosystems; human modification of nutrient cycles can lead to major shifts in ecosystem function. © Brooks/Cole Publishing Company / ITP

22. VI. Ecosystems Respond to Disturbance Natural Disturbances include hurricanes, ice storms, tsunamis, tornadoes, volcanic eruptions, forest fires Anthropogenic include human settlements, agriculture, air pollutions, clear cutting forests, mountain top removal. Occur both short term and long scale.

23. How do disturbances effect flow of energy and cycling of matter? Resistance is the when the ecosystem can resist disturbance; productivity remains relatively unchanged after a disturbance. Can an ecosystem resist the impact and can it recover? Resilience measures the rate at which an ecosystem returns to its original state after a disturbance. Restoration Ecology: Restore damaged ecosystems; Chesapeake Bay

24. Ecosystem Services Instrumental Value  Provisions  Regulating Services  Suport Systems  Resilience  Cultural Services Intrinsic Value