1. Ecosystems: What Are They and How Do They Work? Chapter 3, Part 2

2. Key Concepts PART 1: Ecology: Earth and ecosystems Energy flows PART 2: Matter cycles Studying ecosystems and human impacts

3. W HAT HAPPENS TO MATTER IN AN ECOSYSTEM ? Section 3-4 PART 2

4. Nutrients cycle within and among ecosystems: CHNOPS Elements and compounds move through air, water, soil, rock and living organisms in biogeochemical, or nutrient, cycles. Major nutrients cycling through the biosphere: Carbon (carbon cycle) Hydrogen (water/hydrologic cycle) Nitrogen (nitrogen cycle) Oxygen (through photosynth. and cellular respiration) Phosphorous (phosphorous cycle) Sulphur (sulphur cycle)

5. The Water/Hydrologic Cycle Solar energy evaporates water; the water returns as precipitation (rain or snow), goes through organisms, goes into bodies of water, and evaporates again. Water is filtered and partly purified as it moves through the hydrological cycle. Water can be stored as ice in glaciers or in underground aquifers.

6. Water is unique. It… Is held together by hydrogen bonds. Exists as a liquid over a wide temperate range. Stores a large amount of heat. Requires a large amount of energy to be evaporated. Dissolves a variety of compounds. Filter’s some UV rays from the sun. Can move through capillary action. Expands when freezes. Exists in all three phases at the Earth’s surface.

7. Human Impacts on the water cycle Humans alter the water cycle in many ways: Withdrawing freshwater at faster rates than nature can replenish it. Clearing vegetation which increases runoff and decreases replenishment of groundwater supplies. Draining wetlands which interferes with flood control. Pollution addition of nutrients and/or toxins

8. The Carbon Cycle Carbon is the basic building block of carbohydrates, fats, proteins, DNA, and other compounds. Carbon circulates through the biosphere (all living things), hydrosphere, and atmosphere.

9. Carbon cycle animation- LEARN THE CARBON CYCLE! Carbon Cycle Animation IMPORTANT: Cellular respiration and other chemical break-down of matter (ie burning), photosynthesis, atmosphere, ocean, biosphere http://www.cengage.com/earthscience/book_content/9781111988937_miller/animat

10. Fig. 3-26, p. 56 High projection Low projection Human Impacts on the Global Carbon Cycle 1.Clearing Vegetation 2.Burning Fossil Fuels Consider the consequences…

11. The Nitrogen Cycle Nitrogen gas (N 2 ) makes up 78% of the atmosphere BUT N 2 cannot be used directly by most living organisms. Nitrogen-fixing bacteria convert N 2 into compounds that are useful nutrients for plants and animals.

12. Gaseous Nitrogen (N 2 ) in Atmosphere Synthetic Nitrogen Fixation by industry for agriculture (leads to nitric oxide NO,nitrous oxide N 2 O, nitrogen dioxide NO 2 pollution) Food Webs on Land Fertilizers uptake by autotrophs excretion, death, decomposition uptake by autotrophs Nitrogenous Wastes, Remains in Soil NO 3 – in Soil NO 2 – in Soil loss by leaching 1. Nitrification bacteria convert NH 4 + to nitrite (NO 2 – ) 2. Nitrification bacteria convert NO 2 – to nitrate (NO 3 – ) Ammonification bacteria, fungi convert the residues to NH 3 ; this dissolves to form NH 4 + NH 3, NH 4 + in Soil loss by leaching Nitrogen Fixation bacteria convert N 2 to ammonia (NH 3 ); this dissolves to form ammonium (NH 4 + ) Denitrificatio n by bacteria The Nitrogen Cycle

13. Nitrogen cycle interaction - LEARN THE NITROGEN CYCLE! Nitrogen fixation, Ammonification, Nitrification, Denitrification N is a common limiting factor in agricultural systems (More animations on textbook website) N Cycle Animation http://www.cengage.com/earthscience /book_content/9781111988937_miller/ animations/ch03/animation_media/nitr ogen_cycle_v2/nitrogen_cycle_v2.htm l

14. Human Impacts on the N Cycle 1.Production of inorganic fertilizers and the burning of fossils fuels produce: Nitrogen oxides (NO x ) cause smog and acid rain (includes nitric oxide NO, nitrogen dioxide NO 2 ), AND Nitrous oxide (N 2 O), a powerful greenhouse gas 2.Excess Nitrate (NO 3 -) from fertilizer, agricultural waste, and sewage can leach thru soil to contaminate groundwater and become runoff that causes eutrophication Human agricultural practices have more than doubled the amount of N in the atmosphere and hydrosphere.

15. The Phosphorus Cycle Phosphorus circulates through water, rock, and living things. Phosphorus does not cycle through the atmosphere. Major reservoirs: rock, ocean bottom.

16. Phosphorus cycle animation P is the most common limiting nutrient in natural ecosystems P Cycle Animation http://www.cengage.com/earthscien ce/book_content/9781111988937_m iller/animations/ch03/animation_med ia/phos_anim/phos_anim.html

17. Human Interventions in the Phosphorus Cycle 1.Mining of phosphate rock 2.Clearing tropical forests reduces available phosphate in tropical soils 3.Phosphates from runoff of animal wastes, sewage & fertilizers disrupts aquatic ecosystems - eutrophicationSince 1900, human activities have increased the natural rate of phosphorous release to environment by about 3.7 fold.

18. The Sulfur Cycle Much of the earth’s sulfur is stored underground in rocks and minerals. Hydrogen sulfide (H 2 S) is released from volcanoes and anaerobic decomposition of organic matter in bogs and swamps.

19. S in the atmosphere can lead to acid rain and smog Sulfur cycle animation Sulphur Cycle Animation Humans have been increasing atmospheric sulfur dioxide (SO 2 )-- which causes acid rain and smog--by burning sulfur-containing fuels, refining sulfur-containing fuels, and converting sulfur containing metallic mineral ores into free metals. http://www.cenga ge.com/earthscie nce/book_content /9781111988937_ miller/animations/ ch03/animation_ media/sulfur_cycl e/sulfur_cycle.htm l

20. Nutrient cycling in the environment impacts life in the environment Limiting factor principle - Too much or too little of any abiotic factor can limit or prevent growth of population. Limiting factors:Excess water or water shortages for terrestrial organisms Excess or lack of soil nutrients Dissolved oxygen for aquatic organisms Salinity for aquatic organisms Pollution

21. Lower limit of tolerance Upper limit of tolerance Temperature Low High Abundance of organisms Few organisms Few organisms No organisms No organisms Zone of intolerance Zone of physiological stress Zone of intolerance Zone of physiological stress Optimum range Population Size Range of Tolerance

22. Nutrient and Pollution Levels Influence Populations Range of tolerance : range of abiotic conditions required for population to survive Law of tolerance “The existence, abundance and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by that species.”

23. H OW DO SCIENTISTS STUDY ECOSYSTEMS ? Section 3-5

24. How Do Ecologists Learn about Ecosystems? Field research. Gather comparative baseline data. Remote sensing Geographic information system (GIS). Example: computerized maps of an area that are used to examine forest cover, water resources, air pollution emissions, coastal changes, and changes in global sea temperatures. Laboratory research Systems analysis, Mathematical models, Simulations. All rely on accurate input of “real world” parameters.

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