Ecosystems

1. Ecosystems Chapter 3

2. The study of how organisms interact with one another and their environment Ecology

3. Cells Prokaryote • One-celled organism • Lacks a nucleus • Lacks internal membrane structures • Example – bacteria Eukaryote • Distinct nucleus • Contain organelles with membranes

4. Cells

5. Species • Definition: set of individuals that produce fertile offspring • Nomenclature system – Page S46 in text • How many? Best guess is 10 – 14 million • 1.8 x 106 identified

6. Connections in Nature Population • Group of individuals of same species living in same place at same time • There is genetic diversity (variation) • A habitat is a place where an individual or population lives; a supply of resources

8. Connections in Nature Community • Definition: All the populations of different species living in a certain place • Interaction occurs! This includes feeding, competition for other resources

9. Connections in Nature Ecosystem • Definition: A community of different species interacting with each other and their non-living environment • Huge range in sizes • Natural or artificial • No clear boundaries (erosion, winds, migration, etc)

11. Connections in Nature Biospheres • Definition: parts of the earth, air, water and soil where life is found • A global ecosystem

12. Parts of the earth's air, water, and soil where life is found Biosphere A community of different species interacting with one another and with their nonliving environment of matter and energy Ecosystem Populations of different species living in a particular place, and potentially interacting with each other Community Population A group of individuals of the same species living in a particular place An individual living being Organism The fundamental structural and functional unit of life Cell Chemical combination of two or more atoms of the same or different elements Molecule Smallest unit of a chemical element that exhibits its chemical properties Atom Fig. 3-3, p. 52

13. Keeping Us Alive

15. Components of Life Support Atmosphere • Troposphere: closest to surface of the earth (7-11 km thick); • Majority of air is here (78% N2, 21% O2, 1% CO2, H2O, CH4 – greenhouse gases!)

16. Components of Life Support Atmosphere • Stratosphere: next closest layer, rides on top of troposphere • Most of atmospheric O3 is found here • Ozone absorbs most of the sun’s UV radiation

17. Components of Life Support Hydrosphere • Consists of all water on or near the surface of the earth • May be in liquid form • May be in solid form (ice caps, permafrost, etc.) • May be in vapor form

18. Components of Life Support Geosphere Consists of the: • Core: liquid and solid; produces magnetic field • Mantle: semi-molten state; largest portion of the geosphere • Crust: hard, outermost shell; all our resources are here

19. Components of Life Support Biosphere • Parts of the atmosphere, geosphere, and hydrosphere where life exists • Extends from about 9 km up to the bottom of the ocean

20. Land and Water Biomes • ‘Biome’ only applies to terrestrial portions of the biosphere • A biome will have a distinct climate • A biome will have a distinct set of species Aquatic Life Zones • Includes freshwater and ocean (marine) life zones

22. Factors Sustaining Life One-way flow of high quality energy • Originates from the sun • Travels through organisms • Is dissipated into the environment (low- quality E)

23. Factors Sustaining Life Cycling of Matter (Nutrients) • There is a fixed supply of nutrients/matter • Round trips must be done • Time involved varies from seconds to centuries

24. Factors Sustaining Life Gravity • Keeps the atmosphere around! • Enables movement • Enables cycling

25. The Flow of Energy and Nutrients

26. What Happens to Solar Energy? Comes to earth as shortwave radiation • UV and visible light • 30% is reflected back into space (albedo) • 20% is absorbed by the atmosphere • 50% absorbed by the surface

27. What Happens to Solar Energy? Absorbed energy: • Land, water heat up • They re-radiate in longer wavelengths (IR) • This IR is absorbed or “trapped” by CO2, H2O, etc. • Air heats up – Greenhouse effect • <0.1% is used by green plants

30. Ecosystem Components Living and Nonliving • Abiotic: the nonliving portion; water, air, nutrients, rocks, heat, solar energy • Biotic: the living and once-living; plants, animals, microbes, dead organisms, and waste products • Range of Tolerance: varies for each population in an ecosystem; optimum levels

31. Ecosystem Components Abiotic Factors • Limiting Factors regulate population growth • On land these include precipitation, temperature, nutrients; too much is just as bad as too little • Aquatic: temperature, sunlight, nutrients

33. Ecosystem Components Producers and Consumers • Trophic Level (feeding level): determined by food source of the organism; energy & nutrients are transferred through levels • Autotrophs (Producers): make their own food • Land: plants; • Open water: phytoplankton • Most: photosynthesis; near hydrothermal vents - chemosynthesis

34. Ecosystem Components • (Heterotrophs) Consumers: • Primary: Herbivores • Secondary (carnivores); ex – spiders, frogs, birds • Tertiary (third) or higher; feed on other carnivores • Other terms: omnivores, decomposers, detritivores

36. Ecosystem Components • Aerobic Respiration: • Occurs in cells, energy is obtained from glucose and oxygen • Products are CO2 and H2O • Anaerobic Respiration (Fermentation) • Done by some decomposers • Breakdown of glucose w/out O2; products are methane, ethanol, acetic acid, and H2S

37. Ecosystem Components Energy Flow and Nutrient Cycling • The importance of decomposers • There would be little, if any, nutrient cycling without detritus feeders

39. Energy Flow Energy Flows Through Trophic Levels • Food Chain: sequence of organisms, each of which serves as a food or energy source for the next • Food Web: network of interconnected food chains; most consumers feed on more than one type of organism

42. Energy Flow Usable Energy ↓ With Each Link • Biomass: dry wt. of all the organic matter at a trophic level • Energy transfer is not efficient • Ecological efficiency- The proportion of consumed energy that can be passed from one trophic level to another • 10% is typical • Follows a pyramidal flow

43. Energy Transfer Efficiency and Trophic Pyramids • Biomass- The energy in an ecosystem is measured in terms of biomass. • Standing crop- The amount of biomass present in an ecosystem at a particular time. • Trophic pyramid- The representation of the distribution of biomass among trophic levels.

45. Energy Flow Production Rates • Gross Primary Productivity: rate at which an ecosystem’s producers convert solar E to chem E as biomass • Measured in kcal/m3/yr • Net Primary Productivity (NPP): rate of chem E production minus the rate at which E is used

47. The Flow of Matter Water Cycle: collects, purifies, & distributes H2O • Evaporation • Condensation (precipitation) • Transpiration • Surface runoff: feeds lakes, streams, etc. • Stored: glaciers, aquifers, etc • Humans alter in 3 ways: over-withdrawal, clearing vegetation (erosion), increase flooding ( by draining wetlands)

49. The Flow of Matter Carbon Cycle (Predominant form: CO2) • Producers remove CO2 through photosynthesis • Consumers and decomposers return it via respiration. • Human alter in a big way: • Fossil fuels are the result of millions of years of compression of organic material; storing CO2. In the past 100 years, we have released all that CO2