Ecology, Ecosystems and Food Webs

1. Ecology, Ecosystems and Food Webs

2. Biotic- plants, animals, microbes

3. Abiotic- • physiochemical substances and gradients including byproducts of biotic components (air, nutrients, minerals)

4. population- group of same species existing and interacting in a given areacommunity- groups of different species interacting in a given areaecology- a community interacting with the abiotic components

5. Structure of the Earth • core- innermost solid layer • mantle- second layer containing the plastic asthenosphere and a solid rock layer comprising part of the lithosphere • crust- thinnest outermost layer, includes part of the lithosphere

6. atmosphere consists of: • troposphere- first 11 miles, 78% nitrogen, 21% oxygen • stratosphere- 11-30 miles, contains ozone • mesosphere and thermosphere- two outermost layers

7. hydrosphere • surface and underground water, polar ice caps, icebergs, permafrost and water vapor

8. ecosphere/biosphere • area where living organisms are found, includes parts of lithosphere, atmosphere and hydrosphere

9. First Law: Energy cannot be created or destroyed, just transferred from one form to another Second Law: When ever energy is transferred some energy is lost in the form of heat Thermodynamics

10. What sustains life? • one way energy flow • cycle of nutrients and matter • gravity

11. Types of systems: • open- matter and nutrients can enter system from outside, such as runoff into a stream

12. closed- • system contains all of the matter that it will be able to use, like a biosphere

13. Types of nutrients: • macronutrients- nutrients that organisms need in relatively large amounts

14. role of macronutrients: • O- building block of protoplasm, biological oxidation • C- building block of organic compounds • H- acceptor of oxygen • N- building block of protein, nucleoprotein, enzymes

15. Macronutrients Con’t: • P- photosynthesis component, builder of protein and nucleoprotein • other macrconutrients needed in lesser amounts include S, K, Ca, Mg, Fe

16. micronutrients- • nutrients needed in trace amounts such as Na, Cl, Cu, I, Zn for such varied functions as cell division, carbohydrate metabolism, and nitrogen fixation

17. Types of ecosystems: • terrestrial/biomes • chaparral • coniferous and deciduous forest • desert • prairie • tundra • tiaga • Aquatic • freshwater • marine • estuarine

18. Ecotone • boundary between ecosystems that has characteristics of both

19. How organism survival is determined: • limiting factors- factor that limits growth, too much or too little can inhibit growth • range of tolerance- variations in environmental conditions under which a species can exist, • In general, the greatest number of organisms living in the mid or optimal range

20. Abiotic Factors:

21. Water • necessary for all life (as we know it)

22. special properties of water: • specific heat- (energy required to raise 1 gm of water by 1oC)helps in climate moderation • latent heat- energy required for phase change, water has highest known value, keeps air near lakes and forests cooler • density- reaches maximum at 4oC, allows ice to float, causes water to turn over in bodies of water in the fall and spring

23. Special Properties con’t: • solvency- helps to cycle nutrients • ionization- ability for electrolytic dissociation lends itself to nature • surface tension- lends itself to capillary action and surface tension (second only to Mercury)

24. Albedo:

25. Insolation- incoming solar radiation albedo- reflectivity of earth, how much light bounces off solar flux varies diurnally and seasonally infrared radiation- heats the lower air, water and land

26. Insolation Con’t: • varies in deciduous forests with changes in canopy • degree of temperature change caused depends n presence of water • water quickly extinguishes all wavelengths but blue (ie: color of oceans)

27. Precipitation- • Prevailing winds and topography affect amount of rainfall and therefore determines ecosystem distribution.

28. Water Facts: • only 5% of all water is in circulation, 99% of that 5% is in the ocean • fresh water is about 0.1% of total in circulation, of that 0.1%, 75%(0.075% of total) is tied up in polar ice caps

29. Turnover in the water cycle- • precipitation divided by total water in the atmosphere indicate a turnover rate of every 11 days (or 35 times a year).

30. Temperature • in very wet or very dry ecosystems, temperature is an important limiting factor. • In very hot or very cold ecosystems, moisture is the more important limiting factor

31. Energy Flow: • Energy flows only in one direction (unlike nutrients) in an ecosystem • substantial energy loss occurrs at each trophic level.

32. Trophic level • level with equal number of energy transfers such as primary consumers and secondary consumers. Trophic Pyramid

33. Autotrophs- organisms that produce their own energy supply using solar or chemical energy, producers • Heterotrophs- organisms that rely on other organisms for their energy supply, consumers

34. energy fixation by autotrophs • sunlight plus chlorophyll (or other pigments) • energy is stored as glucose with O2 and water as byproducts • 6CO2 +12H2O  C6H12O6 + 6O2 + 6H2O

35. Measuring the productivity of an ecosystem: • Net Primary Productivity (NPP) = energy incorporated - energy used in respiration

36. This can be done by several methods • Biomass- harvesting and calculating the caloric content of dry weight • CO2 assimilation- measuring how much CO2 is used by the plant (using sensors or clear chambers) • O2 production- used for aquatic systems

37. Illinois cornfield study- • biologists calculated a cornfield used only 1.6% of the available solar energy • of the energy the corn did capture, 23.4% went towards maintaining the plant (mostly cellular respiration).

38. Gross vs. Net Production: • Gross is total, net is what is left after plant maintenance • in fields an average of 15-24% of absorbed energy is used to self maintain • this goes up to 50-60% in temperate forests • and 70-75% in tropical forests

39. Estuaries, swamps and marshes have highest NPP • Open ocean, tundra and desert have the lowest.

40. Food chains/webs: • Producers (autotroph)  primary consumers (heterotrophs) secondary consumer decomposers nutrient pool

41. Example of a food chain: • Plants rabbits (herbivore) (100%) (10%) fox (carnivore)  decomposers (1%) nutrient pool (for use by plants)

42. Energy flows along this same path, but much (about 90%) is lost in the form of heat at each change in trophic level • When you get to a secondary consumer (3rd level), you have only 1% of the initial energy found in the plants.

43. This is known as the ecological efficiency of the food chain or energy pyramid.

44. Biomass* of the different trophic levels is used to convey the total amount chemical energy available in a given ecosystem. * the dry mass of organic material

45. The biomass in a given ecosystem can be shown in the form of a pyramid • The changes in biomass from one level to the next indicate the amount of energy lost in each level for that system

46. The pyramid for grassland has the expected shape, large on the bottom with successively smaller biomasses on top. • However, the biomass pyramid in the ocean appears to have a very small base because much of the first level lives symbiotically inside corals

47. Most systems in nature are more complex than simple food chains • Attempts to show the full relationship are called food webs

48. Example of a shoreline ecosystem:

49. What do healthy ecosystems do: • moderate climate • renew air, water and soil • cycle nutrients • provide energy resources

50. Ecosystems Con’t: • provide food and shelter • slow soil erosion, prevent flooding • natural population control • provide biodiversity