Ecosystems: Components, Energy Flow, and Matter Cycling

1. “All things come from earth, and to earth they all return”—Menander Ecosystems: Components, Energy Flow, and Matter Cycling

2. Ecology and the levels of organization of matter Ecology—Greek oikos meaning house Study of how organisms interact with one another and their non-living environment (biotic and abiotic components) Studies connections in nature on the thin life supporting membrane of air, water, and soil Levels of Organization of Matter Subatomic to biosphere

3. Ecosystem Organization Biosphere Biosphere Ecosystems Communities Populations Organisms • Organisms • Made of cells • Eukaryotic vs Prokaryotic • Species • Groups of organisms that resemble one another in appearance, behavior, and genetic make up • Sexual vs Asexual reproduction • Production of viable offspring in nature • 1.5 million named; 10-14 million likely • Populations • Groups of the same species that live in the same area and interbreed. Fig. 4.2, p. 66

4. Ecosystem Organization Biosphere Biosphere Ecosystems Communities Populations Organisms • Communities • Many populations of organisms living together in one place. • Ecosystems • All of the living and non-living things living together in one place. • Biosphere • All of the Ecosystems of the Earth combined. Fig. 4.2, p. 66

5. Major Ecosystem Components Abiotic Components Water, air, temperature, soil, light levels, precipitation, salinity Sets tolerance limits for populations and communities Some are limiting factors that structure the abundance of populations Biotic Components Living Organisms - Producers, consumers, decomposers Plants, animals, bacteria/fungi Biotic interactions with biotic components include predation, competition, symbiosis, parasitism, commensalism etc.

6. Limiting Factors on Land & in H2O Terrestrial Sunlight Temperature Precipitation Soil nutrients Fire frequency Wind Latitude Altitude Aquatic/Marine Light penetration Water clarity Water currents Dissolved nutrient concentrations Esp. N, P, Fe Dissolved Oxygen concentration Salinity • Limiting Factors: things that prevent a population from growing any larger. For example, 10 rabbits may live in a habitat that has enough water, cover and space to support 20 rabbits, but if there is only enough food for ten rabbits, the population will not grow any larger. Here are a few common limiting factors:

7. Matter & Energy moving in Ecosystem

8. Sustaining Life on Earth… One way flow of high quality energy The cycling of matter (the earth is a closed system) Gravity Causes downward movement of matter Biosphere Carbon cycle Phosphorus cycle Nitrogen cycle Water cycle Oxygen cycle Heat in the environment Heat Heat Heat

9. Energy & Carbon: Photosynthesis

10. Photosynthesis • Converts the sun’s energy into chemical energy stored in sugar. This traps CARBON!! • Takes place in specialized structures inside plant cells called chloroplasts • Chlorophyll is the pigment that absorbs sunlight.

11. Photosynthesis Reaction • 6CO2 + 6 H2O + light energy → C6H12O6 + 6O2 • The food plants make is called glucose (sugar) which can then be turned into any other foods needed for the plant.

12. Photosynthesis • 2 different reactions • Light Reactions • Capture light energy for photosynthesis • Calvin Cycle • Produces glucose sugar

13. Energy & Carbon: Cellular Respiration (Cells) (Breathing) Converts chemical energy from photosynthesis into a usable form of Energy (ATP) for a cell. This occurs in the Mitochondria of Eukaryotic Cells and along the membranes of Prokaryotic Cells.

14. Cellular Respiration • Happens in both plant and animal cells • Overall Reaction: • C6H12O6 + 6O2 → 6CO2 + 6H2O + Energy • *Note that this is the opposite of Photosynthesis

15. Cellular Respiration Overview • Depends on whether or not there is oxygen • Aero = oxygen • Aerobic Respiration – makes a lot energy with Oxygen • Anaerobic Respiration – Fermentation (makes alcohol). Makes a little energy without Oxygen.

17. Photosynthesis & Cell Respiration bring energy from the sun to all living things on our planet but also cycle carbon throughout the Earth and all of it’s ecosystems.

18. The Earth’s Carbon Cycle can be seen here. It is cycled through photosynthesis and cellular respiration but can be stored for a long time in the oceans, lakes, ice bergs, and in the form of fossils. • We release the carbon from fossils when we burn oil and gasoline (fossil fuels). • This is more CO2 than our atmosphere can balance so this leads to Global Warming/Climate Change

19. Ecological communities • Community = an assemblage of species living in the same place at the same time • Members interact with each other • Interactions determine the structure, function, and species composition of the community • Community ecologists = people interested in how: • Species coexist and relate to one another • Communities change, and why patterns exist

20. Energy passes through trophic levels • One of the most important species interactions is who eats whom • Matter and energy move through the community • Trophic levels = rank in the feeding hierarchy • Producers • Consumers • Detritivores and Decomposers

21. Abiotic chemicals (carbon dioxide, oxygen, nitrogen, minerals) Heat Heat Solar energy Heat Decomposers (bacteria, fungus) Producers (plants) Consumers (herbivores, carnivores) Heat Heat Biotic Components of Ecosystems • Producers=autotroph • Source of all food • Photosynthesis • Consumers=heterotroph • Aerobic respiration • Anaerobic respiration • Methane, H2S • Decomposers • Matter recyclers… • Release organic compounds into soil and water where they can be used by producers

22. Producers: the first trophic level • Autotrophs (“self-feeders”) = organisms that capture solar energy for photosynthesis to produce sugars • Green Plants • Cyanobacteria • Algae • Chemosynthetic bacteria use the geothermal energy in hot springs or deep-sea vents to produce their food

23. Consumers: organisms that consume producers • Primary consumers = second trophic level • Organisms that consume producers • Herbivores consume plants • Deer, grasshoppers • Secondary consumers = third trophic level • Organisms that prey on primary consumers • Carnivores consume meat • Wolves, rodents

24. Consumers occur at even higher trophic levels • Tertiary Consumers = fourth trophic level • Predators at the highest trophic level • Consume secondary consumers • Are also carnivores • Hawks, owls • Omnivores = consumers that eat both plants and animals

25. Detritivores and decomposers • Organisms that consume nonliving organic matter • Enrich soils and/or recycle nutrients found in dead organisms • Detritivores = scavenge waste products or dead bodies • Millipedes • Decomposers = break down leaf litter and other non-living material • Fungi, bacteria • Enhance topsoil and recycle nutrients

26. Detritus feeders Decomposers Termite and carpenter ant work Carpenter ant galleries Bark beetle engraving Long-horned beetle holes Dry rot fungus Mushroom Wood reduced to powder Powder broken down by decomposers into plant nutrients in soil Time progression Fig. 4.15, p. 75 Detritivores vs Decomposers

27. First Trophic Level Second Trophic Level Third Trophic Level Fourth Trophic Level Producers (plants) Primary consumers (herbivores) Secondary consumers (carnivores) Tertiary consumers (top carnivores) Heat Heat Heat Heat Solar energy Heat Heat Heat Detritvores (decomposers and detritus feeders) Energy Flow and Matter Cycling in Ecosystems… • Food Chains vs. Food Webs • KEY: There is little if no matter waste in natural ecosystems!

28. Food webs show relationships and energy flow • Food chain = the relationship of how energy is transferred up the trophic levels • Food web = a visual map of feeding relationships and energy flow • Includes many different organisms at all the various levels • Greatly simplified; leaves out the majority of species

29. Humans Blue whale Sperm whale Killer whale Elephant seal Crabeater seal Leopard seal Emperor penguin Adélie penguins Petrel Squid Fish Carnivorous plankton Herbivorous zooplankton Krill Fig. 4.18, p. 77 Phytoplankton Generalized Food Web of the Antarctic Note: Arrows Go in direction Of energy flow…

30. Food Webs and the Laws of matter and energy • Food chains/webs show how matter and energy move from one organism to another through an ecosystem • Each trophic level contains a certain amount of biomass (dry weight of all organic matter) • Chemical energy stored in biomass is transferred from one trophic level to the next • With each trophic transfer, some usable energy is degraded and lost to the environment as low quality heat • Thus, only a small portion of what is eaten and digested is actually converted into an organisms’ bodily material or biomass (WHAT LAW ACCOUNTS FOR THIS?) • Ecological Efficiency: • The % of usable nrg transferred as biomass from one trophic level to the next (ranges from 5-20% in most ecosystems, use 10% as a rule of thumb) • Thus, the more trophic levels or steps in a food chain, the greater the cumulative loss of useable energy…

31. Energy, biomass, and numbers decrease • Most energy organisms use is lost as waste heat through respiration • Less and less energy is available in each successive trophic level • Each level contains only 10% of the energy of the trophic level below it • There are far fewer organisms at the highest trophic levels, with less energy available A human vegetarian’s ecological footprint is smaller than a meat-eater’s footprint

32. Pyramids of energy, biomass, and numbers

33. Heat Heat Tertiary consumers (human) Decomposers Heat 10 Secondary consumers (perch) Heat 100 Primary consumers (zooplankton) 1,000 Heat 10,000 Usable energy Available at Each tropic level (in kilocalories) Producers (phytoplankton) Pyramids of Energy and Matter • Pyramid of Energy Flow • Pyramid of Biomass

34. Implications of Pyramids…. • Why could the earth support more people if the eat at lower trophic levels? • Why are food chains and webs rarely more than four or five trophic levels? • Why do marine food webs have greater ecological efficiency and therefore more trophic levels than terrestrial ones? • Why are there so few top level carnivores? • Why are these species usually the first to suffer when the the ecosystems that support them are disrupted?

35. Ecological Pyramids of Energy