Ecology

1. Ecology What is it?

2. Ecology • Hierarchy of Organization • - Individual • - Population - # of individuals in given area • - Community – all biota in an area • - Ecosystem – all biota & abiotic factors • - Landscape – multiple ecosystems over large area • - Biosphere – all life on Earth

4. Ecology Autecology: study interrelations of individuals with environment Synecology: study of communities

5. Basic Scientific Principles • Law of Conservation of Matter • Matter cannot be created nor destroyed, rather it can only be transformed • 1st Law of Thermodynamics (Energy) • Energy cannot be created nor destroyed, rather it can only be converted in form

6. Basic Scientific Principles • 2nd Law of Thermodynamics • When converting energy, always lose some energy as heat

7. Major Ecosystem Processes • Energy Flow = energy moves through system 2) Nutrient Cycling = chemical elements recycled in system

8. Energy Flow • Solar energy – primary energy source • (fig 3.5, p. 42) • Of incoming solar radiation: • 66% absorbed • 34% reflected (albedo)

9. Solar Energy • Of solar radiation absorbed: • ~22% water cycle • nearly all transform to heat & radiates • emissivity: relative ability of Earth to release energy (e.g., radiate heat into space; link to global warming)

10. Solar Energy • Tiny amount of solar energy into photosynthesis (< 0.1%) • photosynthesis (PNS): use solar energy to convert CO2 & H2O into sugar; by-product = O2 • primary production: all organic matter resulting from PNS; raw material for other organisms (gross production vs. net production)

11. Energy Flow in Communities • food chain: sequence of organisms linked by energy & nutrient flow • trophic level: feeding level/position of organism in food chain

12. Trophic Levels • Producer: (autotrophs) anchor of chain; produce all organic matter for other organisms • Heterotrophs (consumers) • Primary consumer: directly consume producers = herbivores • Secondary consumer: consume herbivores • Tertiary & Quaternary consumers: consume secondary & tertiary consumers, respectively

14. Trophic Levels • Decomposers: (detritus feeder) consume and convert dead material for use by producers

15. Food Webs • food web: interconnected food chains; all trophic interactions in community

17. Human Impacts • Ecosystem simplification: elimination of species from food webs via human alterations to land • Example: vertebrate communities in ag. landscapes

22. Energy Flow Between Trophic Levels • Does 100% of energy transfer from 1 trophic level to another? • No. Remember 2nd Law of Thermodyn. • Range 5-20% transference (usually ~10%) • Graphical representation of energy transference in food web = energypyramid

24. Energy Flow Between Trophic Levels • Why such low efficiency? • Three Reasons: • 1) Escape behavior/protective coloration/unavailable material • 2) Indigestible material • 3) Cellular respiration

25. Bioaccumulation = Biomagnification

26. Nutrient Cycles • What does the Law of Conservation of Matter state? • circular flow of chemicals = recycling • Inputs & relationship to energy flow? • Water, Carbon (C), Nitrogen (N), Phosphorus (P), Sulfur (S)

29. Carbon Cycle • Carbon = building block of life • Reservoirs = atmosphere, ocean, organisms • High rate of exchange in/out reserves • Any relation to global warming?

30. Nitrogen Fixation • Types • 1) atmosphericfixation via lightening or sunlight; NO3 as precipitation (ppt) • 2) biologicalfixation* via soil & water bacteria (blue-green algae); NH3; legumes & root nodules • Water Quality & Nitrates • Soil Condition & Fertilizers

31. Phosphorus Cycle • Water Quality & Phosphorus • Eutrophication: increase in nutrient content of lakes

33. Some Ecological Principles • Individual • Law of Tolerance: organisms can tolerate a range of conditions beyond which they die • e.g., temperature, nutrients • age-dependent, DNA

34. Where does habitat fit? Habitat: home; area having necessary resources (food, water, cover) and environmental conditions (temp., ppt) that allows organism to live & reproduce Your habitat = ????? What if habitat is drastically changed or destroyed? • Move, Adapt, or Die

35. Properties of Communities 1) Species Richness = # species in a comm. 2) Species Evenness = relative abundance of different species 3) Species Diversity = richness & evenness e.g., Four species (A,B,C,D) in 2 different communities Comm 1 – 25A 25B 25C 25D Comm 2 – 97A 1B 1C 1D

36. What Happens in a Community? 1) Competition: individuals contest over a resource (food, space, water, mates…) – major factor determining structure http://fr.truveo.com/The-Raccoon-and-Two-House-Pets/id/2429116624

37. What Happens in a Community? Types of Competition A) Interspecific: competition between different species, e.g., blue jay & chickadee compete for sunflower seed at feeder

38. What Happens in a Community? Types of Competition B) Intraspecific: competition within the same species, e.g., 2 oryx bobcats compete for space

39. Principle of Competitive Exclusion (Gause’s experiments) • Two species which compete for same resource cannot coexist in same place at same time • Implications = different locations or different times • Relates directly to niche concept

40. Niche Concept Niche: functional role (“occupation”) & position (spatial & temporal) of a species in its community • Principle of Competitive Exclusion = 2 species cannot occupy the same niche

41. What Happens in a Community? (cont.) 2) Predation: one species consumes another species

42. Some Ecological Principles • Community • Biological Succession: temporal sequence of one community replacing another; predictable • Primary vs. Secondary

43. Terrestrial Biomes • Biomes - distinguished primarily by their predominant plants and associated with particular climates. • Geographic and seasonal variations in temperature and precipitation are fundamental components.

44. Soil : Foundation of Terrestrial Biomes • Soil is a complex mixture of living and non-living material. • Classification based on vertical layering (soil horizons) • Soil Profile = snapshot of soil structure in a constant state of flux

45. Soil Horizons • O horizon: Organic Layer freshly fallen organic material - most superficial layer • A horizon: Mixture of minerals, clay, silt and sand • B horizon: Clay, humus, and other materials leached from A horizon - often contains plant roots • C horizon: Weathered parent material

46. Tropical Rainforests • Little temperature variation between months • Organisms add vertical dimension • Harbor staple foods and medicines for world’s human populations - increasingly exploited

47. Tropical Dry Forest • Climate more seasonal than tropical rainforest • Heavily settled by humans with extensive clearing for agriculture

48. Tropical Savanna • Climate alternates wet / dry seasons • Fire dependent

49. Desert ~ 20% of earth’s land surface • Water loss usually exceeds precipitation • Human intrusion increasing

50. Mediterranean Woodland & Shrubland (Chaparral) • All continents except Antarctica • Climate cool & moist in fall, winter, and spring; hot & dry in summer • Fire-resistant plants due to fire regime