Studying organisms in their environment

Transcription

1 Ecosystems (Ch. 3)

2 Studying organisms in their environment organism population community ecosystem biosphere

3 Essential questions What limits the production in ecosystems? How does energy move through the ecosystem? How do nutrients move in the ecosystem?

4 Ecosystem All the organisms in a community plus abiotic factors Transform energy & process matter Ecosystems are self-sustaining what is needed? capture energy transfer energy cycle nutrients

5 Ecosystem inputs nutrients cycle constant energy flows input of through energy Matter Don t forget cannot be the created laws of or destroyed Physics! Nutrients cycle biosphere inputs energy nutrients

6 Ecosystem inputs nutrients cycle energy flows through biosphere inputs energy nutrients

7 Energy flows through ecosystems sun secondary consumers (carnivores) loss of energy primary consumers (herbivores) loss of energy producers (plants)

8 Food chains Trophic levels feeding relationships start with energy from the sun captured by plants 1 st level of all food chains food chains usually go up only 4 or 5 levels inefficiency of energy transfer all levels connect to decomposers Level 4 Tertiary consumer top carnivore Level 3 Secondary consumer Level 2 Primary consumer Level 1 Producer Decomposers carnivore heterotrophs herbivore autotrophs Bacteria sun Fungi

9 Inefficiency of energy transfer sun Loss of energy between levels of food chain To where is the energy lost? The cost of living! 12% growth only this energy moves on to the next level in the food chain 35% cellular respiration 53% waste (feces) energy lost to daily living

10 Food webs Food chains are linked together into food webs Who eats whom? a species may weave into web at more than one level bears humans eating meat? eating plants?

11 Ecological pyramid sun Loss of energy between levels of food chain can feed fewer animals in each level ,000 1,000,000,000

12 Humans in food chains Dynamics of energy through ecosystems have important implications for human populations how much energy does it take to feed a human? if we are meat eaters? if we are vegetarian?

13 Generalized Nutrient cycling consumers consumers producers Decomposition connects all trophic levels nutrients ENTER FOOD nutrients CHAIN = made made available available to producers to producers abiotic reservoir decomposers return to abiotic reservoir geologic processes

14 Carbon cycle CO 2 in atmosphere Diffusion Respiration abiotic reservoir: CO 2 in atmosphere enter food chain: Combustion photosynthesis of fuels = carbon fixation in Industry and home Calvin cycle Photosynthesis recycle: decomposition return to abiotic: Plants respiration Animals combustion Dissolved CO 2 Bicarbonates Photosynthesis Animals Plants and algae Deposition of dead material Carbonates in sediment Deposition of dead material Fossil fuels (oil, gas, coal)

15 Nitrogen cycle Carnivores abiotic reservoir: N in atmosphere enter food chain: nitrogen fixation by soil & aquatic bacteria recycle: decomposing & Herbivores nitrifying bacteria return to abiotic: denitrifying bacteria Atmospheric nitrogen Birds Plankton with nitrogen-fixing bacteria Fish excretion loss to deep sediments Death, excretion, feces Decomposing bacteria amino acids Ammonifying bacteria Nitrifying bacteria soil nitrates Plants Nitrogen-fixing bacteria (plant roots) Nitrogen-fixing bacteria (soil) Denitrifying bacteria

16 Loss to deep sediment Phosphorus cycle Loss in drainage Plants Decomposers (bacteria & fungi) Phosphates in solution Land animals Soluble soil phosphate abiotic reservoir: rocks, minerals, soil enter food chain: erosion releases soluble phosphate uptake by plants recycle: decomposing bacteria Animal & fungi tissue Urine and feces return to abiotic: loss to Decomposers ocean sediment (bacteria and fungi) Rocks and minerals Animal tissue and feces Aquatic animals Plants and algae Precipitates

17 Water cycle Water vapor Transpiration Precipitation Evaporation abiotic reservoir: surface & atmospheric water enter food chain: precipitation & plant uptake recycle: Solar energy transpiration return to abiotic: evaporation & runoff Runoff Oceans Lakes Percolation in soil Groundwater Aquifer

18 Review Questions

19 Use the figure below to answer the following question. Examine this food web for a particular terrestrial ecosystem. Each letter is a species. The arrows represent energy flow. 1. Which species is autotrophic? A. A B. B C. C D. D E. E

20 2. If this were a terrestrial food web, the combined biomass of C + D would probably be A. greater than the biomass of A. B. less than the biomass of H. C. greater than the biomass of B. D. less than the biomass of A + B. E. less than the biomass of E.

21 3. If the flow of energy in an Arctic ecosystem goes through a simple food chain from seaweeds to fish to seals to polar bears, then which of the following is true? A. Polar bears can provide more food for Eskimos than seals can. B. The total energy content of the seaweeds is lower than that of the seals. C. Polar bear meat probably contains the highest concentrations of fat-soluble toxins. D. Seals are more numerous than fish. E. The carnivores can provide more food for the Eskimos than the herbivores can.

22 4. Why do most food chains consist of only three to five links? * A. There are only five trophic levels: producers; primary, secondary, and tertiary consumers; and decomposers. B. Most communities are controlled bottom-up by mineral nutrient supply, and few communities have enough nutrients to support more links. C. The dominant species in most communities consumes the majority of prey; thus, not enough food is left to support higher predators. D. According to the energetic hypothesis, the inefficiency of energy transfer from one trophic level to the next limits the number of links that can exist. E. According to the trophic cascade model, increasing the biomass of top trophic levels causes a decrease in the biomass of lower levels, so that the top levels can no longer be supported.