1. ENVIRONMENTAL SCIENCE 13e CHAPTER 3: Ecosystems: What Are They and How Do They Work?

2. Core Case Study: Tropical Rainforests Are Disappearing (1) Found near the equator 2% land surface ~50% world’s known terrestrial plant and animal species ≥50% destroyed or disturbed by humans –Cutting trees –Growing crops –Grazing cattle –Building settlements

3. Core Case Study: Tropical Rainforests Are Disappearing (2) Consequences of disappearing tropical rainforests 1.Decreased biodiversity as species become extinct 2.Accelerated global warming: fewer trees to remove carbon dioxide from the atmosphere 3.Changes regional weather patterns: can lead to increase in tropical grasslands

4. 3-1 What Keeps Us and Other Organisms Alive? Concept 3-1A The four major components of the earth’s life-support system are the atmosphere (air), the hydrosphere (water), the geosphere (rock, soil, sediment), and the biosphere (living things). Concept 3-1B Life is sustained by the flow of energy from the sun through the biosphere, the cycling of nutrients within the biosphere, and gravity.

5. Earth Has Four Major Life- Support Components Atmosphere Hydrosphere Geosphere Biosphere

6. Three Factors Sustain Life on Earth One-way flow of high-quality energy from the sun Cycling of matter or nutrients through parts of the biosphere Gravity

7. Solar Energy Reaching the Earth Electromagnetic waves –Visible light –UV radiation –Heat Natural greenhouse effect Energy in = energy out Human-enhanced global warming

8. 3-2 What Are the Major Components of an Ecosystem? Concept 3-2 Some organisms produce the nutrients they need, others get the nutrients they need by consuming other organisms, and some recycle nutrients back to producers by decomposing the wastes and remains of organisms.

9. Ecology How organisms interact with biotic and abiotic environment Focuses on specific levels of matter: –Organisms –Populations –Communities –Ecosystems –Biosphere

10. Living and Nonliving Components (1) Abiotic –Water –Air –Nutrients –Solar energy –Rocks –Heat

11. Living and Nonliving Components (2) Biotic –Plants –Animals –Microbes –Dead organisms –Waste products of dead organisms

12. Trophic Levels (1) Producers – autotrophs –Photosynthesis Consumers – heterotrophs –Primary - herbivores –Secondary - carnivores –Third-level Omnivores

13. Trophic Levels (2) Decomposers –Release nutrients from the dead bodies of plants and animals Detrivores –Feed on the waste or dead bodies of organisms

14. Production and Consumption of Energy Photosynthesis Carbon dioxide + water + solar energy  glucose + oxygen Aerobic respiration Glucose + oxygen  carbon dioxide + water + energy

15. Energy Flow and Nutrient Recycling Ecosystems sustained through: –One-way energy flow from the sun –Nutrient recycling

16. Science Focus: Invisible Organisms (1) Microorganisms/Microbes –Bacteria –Protozoa –Fungi –Phytoplankton

17. Science Focus: Invisible Organisms (2) Microbes can cause disease –Malaria –Athlete’s foot Microbes are also beneficial –Intestinal flora –Purify water –Phytoplankton remove carbon dioxide from the atmosphere

18. 3-3 What Happens to Energy in an Ecosystem? Concept 3-3 As energy flows through ecosystems in food chains and webs, the amount of chemical energy available to organisms at each succeeding feeding level decreases.

19. Energy Flow in Ecosystems Trophic levels Food chain –Sequence of organisms, each of which serves as a source of food for the next Food web –Network of interconnected food chains –More complex than a food chain

20. Usable Energy by Trophic Level Energy flow follows the second law of thermodynamics – energy lost as heat Biomass decreases with increasing trophic level Ecological efficiency – typically 10% Pyramid of energy flow

21. Two Kinds of Primary Productivity Gross primary productivity (GPP) Net primary productivity (NPP) Planet’s NPP limits number of consumers Humans use, waste, or destroy 10- 55% of earth’s total potential NPP Human population is less than 1% of total biomass of earth’s consumers

22. 3-4 What Happens to Matter in an Ecosystem? Concept 3-4 Matter, in the form of nutrients, cycles within and among ecosystems and in the biosphere, and human activities are altering these chemical cycles.

23. Biogeochemical Cycles Nutrient cycles Reservoirs Connect all organisms through time

24. Hydrologic Cycle Water cycle is powered by the sun 1.Evaporation 2.Precipitation 3.Transpiration - evaporates from plant surfaces Water vapor in the atmosphere comes from the oceans – 84% Over land, ~90% of water reaching the atmosphere comes from transpiration

25. Science Focus: Water’s Unique Properties (1) Holds water molecules together – hydrogen bonding Liquid over a wide temperature range Changes temperature slowly Requires large amounts of energy to evaporate

26. Science Focus: Water’s Unique Properties (2) Dissolves a variety of compounds Filters out UV light from the sun Adheres to a solid surface – allows capillary action in plants Expands as it freezes

27. Carbon Cycle Based on carbon dioxide (CO 2 ) CO 2 makes up 0.038% of atmosphere volume Major cycle processes –Aerobic respiration –Photosynthesis –Fossil fuel combustion and deforestation Fossil fuels add CO 2 to the atmosphere and contribute to global warming

28. Nitrogen Cycle Multicellular plants and animals cannot utilize atmospheric nitrogen (N2) Nitrogen fixation Nitrification Ammonification Denitrification

29. Phosphorus Cycle Does not cycle through the atmosphere Obtained from terrestrial rock formations Limiting factor on land and in freshwater ecosystems Biologically important for producers and consumers

30. Sulfur Cycle Most sulfur stored in rocks and minerals Enters atmosphere through: –Volcanic eruptions and processes –Anaerobic decomposition in swamps, bogs, and tidal flats –Sea spray –Dust storms –Forest fires

31. 3-5 How Do Scientists Study Ecosystems? Concept 3-5 Scientists use field research, laboratory research, and mathematical and other models to learn about ecosystems.

32. Field Research Collecting data in the field by scientists Remote sensing devices Geographic information systems (GIS)

33. Laboratory Research Simplified model ecosystems –Culture tubes –Bottles –Aquariums –Greenhouses –Chambers with controllable abiotic factors How well do lab experiments correspond with the greater complexity of real ecosystems?

34. Scientific Studies of Ecosystems Models –Mathematical –Computer simulations Models need to be fed real data collected in the field- baseline data Models must determine relationships among key variables

35. Baseline Data to Measure Earth’s Health Needed to measure changes over time Lacking for many ecosystems Call for massive program to develop baseline data