Chapter 7

1. Chapter 7 Environmental Systems and Ecosystem Ecology

2. The Gulf of Mexico’s “Dead Zone” • In 2002, grew to its largest size ever - 8,500 square miles. • so depleted of oxygen that it cannot support marine organisms, a condition called hypoxia • Fertilizer runoff from midwestern farms is a major cause • Other causes - urban runoff, industrial discharge, fossil fuel combustion, and municipal sewage

3. Earth’s Environmental Systems • System - relationships of components that interact with and influence one another through the exchange of energy, matter, and/or information. • receive input, process it, and produce output. • output can serve as input to that same system in a circular process called a feedback loop.

4. Earth’s Environmental Systems • negative feedback loop - output from the system acts as input that moves the system in the other direction • Thermostat • Body temperature • Predator-prey populations • Common in nature

5. Earth’s Environmental Systems • positive feedback loop, the output drives the system further toward one extreme. • Exponential growth in the human population • Spread of cancer • Erosion of soil • Rare in nature • Common in natural systems altered by humans

6. Earth’s Environmental Systems • If inputs and outputs of a complex natural system are in balance, it is called a dynamic equilibrium. • contributes to homeostasis, where the tendency of the system is to maintain stable internal conditions

7. Earth’s Environmental Systems • Difficult to understand systems by focusing on individual components • Systems can show emergent properties - characteristics that are not evident in individual components

8. Earth’s Environmental Systems • Page 177 • Tree’s components • Acorn, branches, trunk, chloroplasts (leaves) • Tree’s emergent properties • Part of forest ecosystem, collects CO2, habitat Can you think of other organisms’ components vs. emergent properties?

9. Earth’s Environmental Systems • Systems rarely have well-defined boundaries • closed system - isolated and self-contained, no interactions with other systems, does not occur in nature • open system exchanges energy, matter, and information with other systems, all systems on Earth are open systems.

10. Vocab Quiz Friday! • Study Time! • Two options • Make flashcards • Quiz with game boards

11. Earth’s Environmental Systems • Understand the dead zone – know the systems • 1. Hypoxia in the Gulf of Mexico - excess N from the Mississippi River watershed. • 2. Excess nutrients • runoff from fertilized fields • manure • crop residues • sewage • industrial and automobile emissions.

12. Earth’s Environmental Systems • 3. Nutrients reach the Gulf, boost growth of microorganisms; provide food for bacterial decomposers • 4. Decomposers use O2 in water; fish and shrimp suffocate and die. • 5. Process of nutrient enrichment, algal bloom, bacterial increase, and ecosystem deterioration is called eutrophication.

13. Earth’s Environmental Systems • Categorizing environmental systems • atmosphere - air surrounding our planet. • hydrosphere - all water in surface bodies, underground, and in atmosphere • lithosphere - everything solid earth beneath our feet • biosphere - sum total of all the planet’s biotic and abiotic

14. Ecosystems • Ecosystems are systems of interacting living and nonliving entities • Energy for most ecosystems sun converted to biomass (organic material) • Autotrophs capture the sun’s energy through photosynthesis - gross primary production • Net Primary Production - energy stored by plants after respiration

15. Ecosystems • Flow of energy and matter • Page 180, Figure 7.6

16. Ecosystems • Ecosystem outputs - energy (heat), water, and waste products • Ecosystems that produce large amounts of biomass - high net primary productivity. • Absence of one or more critical nutrient molecule or element can limit net primary productivity • Nutrient increase causes high primary productivity

17. Ecosystems • Landscape ecology -how landscape structure affects organisms. • ecotone - where two or more ecosystems meet; contains elements from each ecosystem

18. Book Work • Partners • Each must have your own paper to turn in • Page 183 – Weighing the Issues – answer all questions • Page 202 – Testing Your Comprehension • #s 1-4 – answer all parts of questions

19. Biogeochemical Cycles • Nutrients movement • travel from one organism to another, moving between reservoirs, remaining in a reservoir for a residence time. • Movement between reservoirs is called flux; the rates of flux can change, typically involves negative feedback loops • Human activity has changed some flux rates.

20. Carbon Cycle • Carbon - in carbs, fats, proteins, bones, cartilage, shells • Producers pull CO2 out of the atmosphere to produce O2 and carbohydrates. • Respiration - carbohydrates broken down to produce CO2 and H2O.

21. Carbon Cycle • Humans are shifting C from the lithosphere to the atmosphere. • Mining for fossil fuels and burning vegetation removes C from reservoirs and increase the flux into the atmosphere • Ongoing flux of C into the atmosphere is a major force behind global climate change.

22. Carbon Cycle • Atmospheric scientists remain baffled by the “missing carbon sink,” the roughly 1–2 billion metric tons of C unaccounted for that we anticipate should be in the atmosphere due to fossil fuel combustion and deforestation. • What would happen if the “missing carbon” was suddenly released?