Introduction to Ecological Principles

1. Introduction to Ecological Principles September – October 2011

2. The Field of Ecology • study of how organisms interact with one another and with their non-living environment. • from Greek “oikos” meaning “house” • segment of biological sciences focused on organism to biosphere interactions

3. Ecology is the study of organisms in their “Home”Oikos = “Home” “By ecology we mean the body of knowledge concerning the economy of nature--the investigation of the total relations of the animal both to its inorganic and its organic environment; including, above all, its friendly and inimical relations with those animals and plants with which it comes directly or indirectly into contact--in a word, ecology is the study of all those complex interrelations referred to by Darwin as the conditions of the struggle for existence.” Ernst Haeckel, 1870

4. Unit 2 Summary – Ch.3-7 Topic: Ecology & Evolution • Basics of Ecology • Atmospheric Structure • Climate & Weather • Biomes & Aquatic Life Zones • Biogeochemical cycling • Productivity • Species diversity • Evolution • Inter- and intraspecific relationships • Ecological succession

5. Oceanic Crust Continental Crust Atmosphere Vegetation and animals Biosphere Lithosphere Soil Upper mantle Crust Asthenosphere Rock Lower mantle Core Mantle Crust (soil and rock) Biosphere (living and dead organisms) Hydrosphere (water) Lithosphere (crust, top of upper mantle) Atmosphere (air) Fig. 3-6, p. 54

6. The Sun: The Ultimate Source • Solar energy flows through the biosphere. • warms the atmosphere • evaporates and recycles water • generates winds • supports the growth of producers Figure 3-8

7. What Sustains Life on Earth? Solar energy Cycling of matter Gravity Figure 3-7

8. Biomes & Aquatic Life Zones Figure 3-9

9. Energy Flow • First Law of Thermodynamics: Energy cannot be created nor destroyed, but can change from one form to another. • Second Law of Thermodynamics: When energy is converted to another form, some of it is changed to heat that is unavailable to do further work. • For thermodynamic purposes, matter can be thought of as a form of energy. • Energy “flows” through communities (usually from the sun), “losing”usable energy each time one organism consumes another.

10. Sun Oxygen (O2) Producer Carbon dioxide (CO2) Secondary consumer (fox) Primary consumer (rabbit) Precipitation Producers Falling leaves and twigs Soil decomposers Soluble mineral nutrients Water Fig. 3-10, p. 57

11. Populations • A population is a group of interacting organisms of the same species occupying a specific area at the same time. • Why study the population? • management unit • source of natural resources/natural capital Figure 3-4: Population of monarch butterflies on a milkweed plant

12. Characteristics of Populations • Habitat – place where a population normally lives Credit: Charissa Morris / USFWS • Range – area over which we can find species • May be a specific habitat or a collection of suitable habitats • Sometimes called distribution Credit: U.S. Fish & Wildlife Service

13. Factors That Limit Population Growth Lower limit of tolerance Upper limit of tolerance No organisms Few organisms Few organisms No organisms Abundance of organisms Population size Zone of intolerance Zone of intolerance Zone of physiological stress Zone of physiological stress Optimum range Low Temperature High Fig. 3-11, p. 58

14. Factors That Limit Population Growth • The physical conditions of the environment can limit the distribution of a species. Figure 3-12

15. Types of Organisms in Ecosystems • Autotrophic organisms = Producers • Means “self feeders” • A. Photosynthetic organisms • Use light as an energy source • Green plants, algae, photosynthetic bacteria • B. Chemosynthetic bacteria • Oxidize inorganic chemicals as an energy source • Use reduced forms of sulfur, nitrogen, iron • Thiobacillusthiooxidans, Nitrobacter spp., Nitrosomonasspp., Thiobacillusferroxidans

16. Photosynthesis: A Closer Look • Chlorophyll molecules in the chloroplasts of plant cells absorb solar energy. • This initiates a complex series of chemical reactions in which carbon dioxide and water are converted to sugars and oxygen. Figure 3-A

17. Types of Organisms in Ecosystems (continued) • Heterotrophic organisms • Means “to feed on others” • A. Consumers • Animals which usually eat other living things • Herbivores – consume producers • Carnivores – consume other consumers • Omnivores – consume both producers and consumers • B. Detritivores & Decomposers • Worms, maggots, small arthropods that are shredders of large detritus • Bacteria & fungi

18. What are these?

19. Type of Organism?

20. Decomposers and Detrivores • Decomposers: Recycle nutrients in ecosystems. • Detrivores: Insects or other scavengers that feed on wastes or dead bodies. Figure 3-13

21. Detritus

22. Leaf Litter Detritus

23. Dung Beetle (Detritivore)

24. Decomposers • Bacteria • Fungi

25. Aerobic and Anaerobic Respiration: Getting Energy for Survival • Organisms break down carbohydrates and other organic compounds in their cells to obtain the energy they need. • This is usually done through aerobic respiration. • The opposite of photosynthesis

26. Aerobic and Anaerobic Respiration: Getting Energy for Survival • Anaerobic respiration or fermentation: • Some decomposers get energy by breaking down glucose (or other organic compounds) in the absence of oxygen. • The end products vary based on the chemical reaction: • Methane gas • Ethyl alcohol • Acetic acid • Hydrogen sulfide

27. Two Secrets of Survival: Energy Flow and Matter Recycle • An ecosystem survives by a combination of energy flow and matter recycling. Figure 3-14

28. ENERGY FLOW IN ECOSYSTEMS • Food chains and webs show how eaters, the eaten, and the decomposed are connected to one another in an ecosystem. Figure 3-17

29. Food Chains

30. Food Webs • Trophic levels are interconnected within a more complicated food web. Figure 3-18

31. Energy Flow in an Ecosystem: Losing Energy in Food Chains and Webs • In accordance with the 2nd law of thermodynamics, there is a decrease in the amount of energy available to each succeeding organism in a food chain or web.

32. Trophic Levels & Energy Pyramids

33. Heat Heat Tertiary consumers (human) Decomposers Heat 10 Secondary consumers (perch) Heat 100 Primary consumers (zooplankton) 1,000 Heat Producers (phytoplankton) 10,000 Usable energy Available at Each tropic level (in kilocalories) Fig. 3-19, p. 66

34. Ecological Pyramids Explained

35. Productivity • Defined as “the rate at which organisms in one trophic level convert energy from the previous trophic level into its own level” • Primary Productivity • The rate at which producers either photosynthesize(green plants) or oxidize inorganic compounds (chemosynthetic bacteria) • Secondary Productivity • The rate at which consumers or decomposers convert energy from a prior trophic level into their own level

36. Primary Productivity • Gross Primary Productivity (GPP or Pg) • The total productivity of all producers in an ecosystem (e.g. total amount of energy fixed by photosynthesis and/or chemosynthesis) • Rate at which an ecosystem’s producers convert solar energy into chemical energy as biomass. • Respiration (R) • Metabolic costs of the producers • Net Primary Productivity (NPP or Pn) • The amount of productivity left over after producer metabolism is subtracted • This equals the amount of energy remaining for producer growth and reproduction • NPP = Growth + Reproduction • GPP = NPP + R

37. GPP=NPP+R GPP = Total Assimilation of organic material NPP = Growth + Reproduction

38. Gross primary productivity (grams of carbon per square meter) Fig. 3-20, p. 66

39. Net Primary Production (NPP) • NPP = GPP – R • Rate at which producers use photosynthesis to store energy minus the rate at which they use some of this energy through respiration (R). Figure 3-21

40. Measuring Primary Production • Harvest Method • Traditionally used in terrestrial communities • Light/Dark Bottle Method • Used in aquatic communities • Radioisotope Methods • Can be used in either terrestrial or aquatic communities

41. Comparison of Net Primary Productions

42. What are nature’s three most productive and three least productive systems? Figure 3-22