2.2.2.1 Structure of an Ecosystem

1. 2.2.2.1 Structure of an Ecosystem

2. Ecosystems • a community of interdependent organisms and the physical environment they inhabit.

3. Ecology • the study of the inter-relationships of organisms with each other and the environment..

4. Ecosystem Components 2 parts • Abiotic – nonliving components (water, air, nutrients, solar energy) • Biotic – living components (plants, animals, microorganisms) Biota

5. Aquatic Life Zones Terrestrial Ecosystems • Light penetration • Water currents • Dissolved nutrient concentrations (especially N and P) • Suspended solids • Salinity • Sunlight • Temperature • Precipitation • Wind • Latitude (distance from equator) • Altitude (distance above sea level) • Fire frequency • Soil Significant abiotic factors

6. What abiotic factors effect this Aquatic food chain?

7. The abiotic influence • Species thrive in different physical conditions • Population has a range of tolerance for each factor • Optimum level best for most individuals • Highly tolerant species live in a variety of habitats with widely different conditions

8. 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 physiological stress Optimum range Zone of physiological stress Zone of intolerance Low High Temperature The Law of Tolerance: The existence, abundance and distribution of a species in an ecosystem are determined by whether the levels of one or more physical or chemical factors fall within the range tolerated by that species

9. Abiotic factors may be Limiting Factors • Limiting factor – one factor that regulates population growth more than other factors • Too much or too little of an abiotic factor may limit growth of a population • Determines K, carrying capacity of an area • Examples • Temperature, sunlight, dissolved oxygen (DO), nutrient availability

10. Terminology and Roles of Biota • Producers (Autotrophs) – Through photosynthesis convert radiant to chemical energy (energy transformation) • Consumers (Heterotrophs) – Must consume other organisms to meet their energy needs • Herbivores, Carnivores, Omnivores, Scavengers, Detritivores • Decomposers – Break down organisms into simple organic molecules (recycling materials)

12. Tropic Levels • The terms producer, primary consumer, secondary consumer and tertiary consumer refer to the organisms feeding level in a food chain or web – this is called its TROPHIC LEVEL.

13. Tropic Levels • TROPHIC LEVEL – the position that an organism occupies in a food chain, or a group of organisms in a community that occupy the same position in food chains.

14. Food chains • Food chain - Sequence of organisms each of which is the source of food for the next

15. Food chains • Feeding levels in the chain (Trophic levels) • First trophic level = producer • Second trophic level = consumer, herbivore • Third trophic level = consumer, carnivore • Highest trophic level = top carnivore • Arrows indicate direction of energy flow!!! • Decomposers are not included in food chains and webs

16. Producers • Transform energy into a usable form • Starting form may be light energy or inorganic chemicals • Turned into organic chemical energy • This is the form that is used at other trophic levels

17. Food Webs • Ecosystem is an energy machine and a matter processor • Autotrophs: make their own food (plants algae & photosynthetic prokaryotes) • Heterotrophs: directly or indirectly depend on photosynthetic output of primary producers

18. Photoautotrophs

19. Consumers • Heterotrophs: get energy from organic matter consumed • Primary, Secondary & Tertiary consumers • Herbivores  primary consumers, eat plant material e.g. – termites, deer • Carnivores  other consumer levels, eat animal material e.g. eagles, wolves • Omnivores  consumers eating both e.g. bears

20. Figure 53.0 Lion with kill in a grassland community

21. Decomposition • Decomposers obtain energy by breaking down glucose in the absence of oxygen • Anaerobic respiration or fermentation • End products = methane, ethyl alcohol, acetic acid, hydrogen sulfide • Matter recycling  inorganic nutrients returned to producers

22. Detritus feeders Decomposers Bark beetle engraving Carpenter ant galleries Termite and carpenter ant work Long-horned beetle holes Dry rot fungus Wood reduced to powder Mushroom Powder broken down by decomposers into plant nutrients in soil Time progression Decomposition Process

23. Consumers or Decomposers • Detritivores = get their energy from detritus, nonliving organic material  remains of dead organisms feces, fallen leaves, wood • May link producers to consumers • Dung beetles, earth worms • Saprotrophs = feed on dead organic material by secreting digestive enzymes into it and absorbing the digested products • Producers can reassimilate these raw materials • Fungi (mold, mushrooms), bacteria

24. Figure 53.10 Examples of terrestrial and marine food chains

25. Local examples

26. Food chains • For complexity a real ecosystem needs FOOD WEB which shows that individuals may exist at multiple trophic levels in a system (omnivores)

27. Figure 53.11 An antarctic marine food web: Identify the trophic levels

28. Food Webs • Food webs are limited by the energy flowing through them and the matter recycling within them