Ecology and the Environment (Chapter 22)

1. Ecology and the Environment(Chapter 22) • Background and Historical Development • Attributes of Ecological Systems • Selected Issues – Applied Ecology • Take Home Messages

2. Take-Home Messages • Functional unit in ecology is the ecosystem; it is analogous to the cell • Hierarchy theory and emergent properties is applicable to the study of ecology • Energetics of ecosystems is driven by (i) principles of thermodynamics (1st and 2nd Laws) and (ii) nature in which organisms acquire and utilize energy; result is a predictable pattern among all ecosystems embodied in the concept of trophic levels • Ecosystems are not static but change over time in predictable and recurrent ways; this change is called succession • Energy passes through ecosystems unidirectionally, whereas elements/materials cycle throughout ecosystems • Biodiversity, the number and distribution of species, is an important feature of ecosystems

3. Ecologyand the Environment • Background and Historical Development • Attributes of Ecological Systems • Selected Issues – Applied Ecology • Take Home Messages

4. Background and Historical Context • Discipline of ecology • Evolution of the science • Orientation by type of system

5. Discipline • 1950’s: emergence of the discipline • Stimulus: technological changes • Harnessing the atom (radioactive elements) • Rachel Carson’s Silent Spring • Two sub-disciplines • Basic ecology • Structure and function of ecosystems • Applied ecology • Human-altered and “managed” ecosystems

6. Evolution • Early to mid 1900 • descriptive natural history • > 1950’s • Experimentally and hypothesis driven research • > 2000 • Experimentally and hypothesis driven research • Mathematical modeling at a global scale

7. Types of Ecosystems • Natural ecosystems • Grasslands, unmanaged forests, wetlands, rivers, etc. • Key: ecological systems that are largely unmanaged for human use • Human-dominated ecological systems • Agroecosystems, managed forest (timber), fish farms, urban/suburban landscapes, etc. • Key: ecosystems that are harvested by humans and are subsidized (fertilizer, water, pest management, etc.) • Attributes in common • Same basic structure and function (principles are the same)

8. Attributes • Ecosystem (ecological system) • Hierarchy theory and emergent properties • Structure of ecosystems • Energetics of ecosystems (flow of energy) • Biodiversity • Cycles of materials and elements

9. Ecology • Background and Historical Development • Attributes of Ecological Systems • Selected Issues – Applied Ecology • Take Home Messages

10. Attributes • Ecosystem • Hierarchy theory and emergent properties • Structure of ecosystems • Energetics of ecosystems (flow of energy) • Biodiversity • Cycles of materials and elements

11. Ecosystems • Ecological systems – ecosystem • Components • Biotic components • All living organisms – plants, animals and microbes • Abiotic components • All non-living components – soil, atmosphere, water, climate, etc. • Ecosystem • Fundamental unit of ecology; analogous to that of the cell

12. Hierarchy Theory and Emergent Properties Earth Biosphere Biome Ecosystem Community Population Organisms

13. Terms • Population: assemblage of individuals of the same species in the same area • Community: assemblage of all species in a given area • Biome: large regional units of several different types of ecosystems existing in same general area • Biosphere: all of the Earth’s biomes at the global scale (shuttle frame of reference)

14. Major Biomes

15. Emergent Properties • Hierarchy theory and emergent properties • Relate to ecology • Emergent properties • Water (combination of H and O) • Sodium chloride (combination of Na and Cl) • Mixes species forest (combination of 50+ different species of trees, shrubs, microbes and animals) • Unanticipated properties

16. Attributes • Ecosystem (ecological system) • Hierarchy theory and emergent properties • Structure of ecosystems • Energetics of ecosystems (flow of energy) • Biodiversity • Cycles of materials and elements

17. Structure of Ecosystems • Structure is underpinned by flow of energy • Autotrophs: fix energy from sun - plants • Heterotrophs: consume energy in C-C bonds • Primary consumers - herbivores • Secondary consumers – carnivores and omnivores • Tertiary consumers – saprovores (dead organic matter) • All organisms are classified by their source of energy

18. Trophic Levels of an Ecosystem

19. Attributes • Ecosystem (ecological system) • Hierarchy theory and emergent properties • Structure of ecosystems • Energetics of ecosystems (flow of energy) • Biodiversity • Cycles of materials and elements

20. Energetics of Ecosystems • Common theme/attribute to all ecosystems • Linkage to physics • 1st Law of Thermodynamics (conservation) • 2nd Law of Thermodynamics (entropy increases) • Highly order state of all ecosystems is function of transforming energy in trophic structure • Thermodynamics: dissipation of energy is most common in form of heat and respiration

21. Keys to Energetics • Energy flows through ecosystems unidirectionally • As energy flows, amount of energy available to do work (potential energy in C-C bonds) decreases • Flow of energy places constraints on the number of organisms that can exist in higher trophic levels

22. Quantification of Energy Flow 30 Consumers 10% 2nd Consumers 10% 10 Consumers 10% Autotrophs 1% Sun Respiration and heat

24. Trophic Levels of an Ecosystem

25. Attributes • Ecosystem (ecological system) • Hierarchy theory and emergent properties • Structure of ecosystems • Energetics of ecosystems (flow of energy) • Biodiversity • Cycles of materials and elements

26. Biodiversity • Diversity of world’s biota: ~100 Million species, of which 1.5 Million have been catalogued • Biodiversity: measurement of the diversity of flora, fauna and microbes • Species richness (number of species)

27. Biodiversity

28. Biodiversity: Arid Landscaspes

29. Biodiversity: Significance • Humanistically: intuitively value (appreciate diversity of life forms) • Ecologically: evidence that biodiversity is related to stability and functioning of ecosystems • Declining biodiversity with human population

30. Attributes • Ecosystem (ecological system) • Hierarchy theory and emergent properties • Structure of ecosystems • Energetics of ecosystems (flow of energy) • Biodiversity • Cycles of materials and elements

31. Cycling of Elements and Materials • Unlike energy, elements and materials cycle throughout ecosystems and they are re-used • Examples: water, carbon, nitrogen • Path is commonly circular passing from biosphere to geosphere to hydrosphere to atmosphere

32. Basic Cycling Model Atmosphere Biosphere Hydrosphere Geosphere

33. Cycling of Elements: Nitrogen

34. Ecology • Background and Historical Development • Attributes of Ecological Systems • Selected Issues – Applied Ecology • Take Home Messages

35. Human Population Growth o

36. Selected Issues in Ecology • Acid rain • Biodiversity and habitat loss • Climate change – a global issue • Ozone and particulate matter in the atmosphere • Stratospheric ozone and UV-B radiation • Tropospheric ozone and human health • PM and human health

37. Take-Home Messages • Functional unit in ecology is the ecosystem; it is analogous to the cell • Hierarchy theory and emergent properties is applicable to the study of ecology • Energetics of ecosystems is driven by (i) principles of thermodynamics (1st and 2nd Laws) and (ii) nature in which organisms acquire and utilize energy; result is a predictable pattern among all ecosystems embodied in the concept of trophic levels • Ecosystems are not static but change over time in predictable and recurrent ways; this change is called succession • Energy passes through ecosystems unidirectionally, whereas elements/materials cycle throughout ecosystems • Biodiversity, the number and distribution of species, is an important feature of ecosystems