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2.5 Ecosystem Functions

1Major roles in an ecosystemProducers-Convert sunlight energy into organic matterConsumers- Use living organic matter as energy to grow and developDecomposers- Break down the dead organic matter / return nutrients to the soil

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3ENERGY ENTERS THE ECOSYSTEM AS SUNLIGHTOnly 2% of the light energy falling on plant is used to create energyThe rest is reflected, or just warms up the plant as it is absorbed

4Photosynthesis Process where plants use sunlight energy to create chemical energyPhotosynthesis: equation 6CO2 + 6H2O --> C6H12O6 + 6O2Inputs: light energy, water, carbon dioxideOutputs: oxygen gas, sugarEnergy transformations: Light to Chemical

5Cellular RespirationProcess by which animals create energy through consumption of organic molecules (sugars)Respiration: C6H12O6 + 6O2 --> 6CO2 + 6H2OInputs: oxygen gas, organic molecules (sugars)Outputs: carbon dioxide, energy in ATP, waste heatEnergy transformations: chemical to heatPhotosynthesis backwards!

6Energy Transfers in EcosystemWhere does all the energy go?2.1.7 Describe and explain population interactions using examples of named species. Include competition, parasitism, mutualism, predation and herbivory. Mutualism is an interaction in which both species derive benefit. Interactions should be understood in terms of the influences each species has on the population dynamics of others, and upon the carrying capacity of the others environment. Graphical representations of these influences should be interpreted.

2.1.6 Define the terms species, population, habitat, niche, community and ecosystem with reference to local examples.

FLIPCAST Species concept

FLIPCAST Food chains and the carbon cycle

CASE STUDYCalifornia salamanders

ESSENTIAL QUESTIONS

How can a species occupy two different trophic levels simultaneously in the same food web?

Decomposers and consumers seem to be doing essentially the same thing. Why do environmental scientists bother to make a distinction between them?

Energy transfers are always inefficient. In food chains roughly 90% of energy is lost as heat. Where does this heat go? Is this consistent with viewing the biosphere as a closed system?

ESSENTIAL QUESTIONS

What does the unit J.m-2.y-1 measure? Show that you understand the unit by breaking it down and explaining the significance of each component.

Explain why the pyramid of biomass in aquatic ecosystems is often inverted?

Why are harmful, non-biodegradable chemicals often found in higher concentrations in the bodies of creatures at the very top of food chains?

ESSENTIAL QUESTIONS

Why do biologists say that no two species may occupy the same niche?

What is the difference between interspecific and intraspecific competition?

Parasites are harmful; but not too harmful. Why do most parasites not kill their hosts?

ENDGAMEIB EXAMINATION REVIEW There is a menu containing the entire collection of Essential Questions from the various syllabus sections. Understanding these big picture ideas and being able to apply them in novel situations is the key to examination success in Environmental Sysytems and Societies. The is also a menu of Facts and Skills and a convenient review strategy called Differentiations of Mastery.

ENDGAME QUESTIONS:

1. WHAT BIG PICTURE IDEAS DO YOU NEED TO UNDERSTAND? 2. WHAT MUST YOU BE ABLE TO DO? 3. WHAT FACTS DO YOU NEED TO LEARN?

7Energy Flow Diagram

8Water Cycle

9Nitrogen Cycle

10Carbon Cycle

11Gross productivityTotal energy captured or assimilated by an organism.Measured in joules (J)Plant (Gross Primary Productivity)GPP = sunlight energy used during photosynthesisAnimals (Gross Secondary Productivity)GSP = food eaten - energy in faeces

Energy is stored in leaf as sugars and starches, which later are used to form flowers, fruits, seeds,

12Net productivity The energy left over after organisms have used what they need to survive.All organisms have waste energy and respiratory loss given off as heat, metabolism (R)Plants and animals have to use some of the energy they capture to keep themselves growing:They both move water and stored chemicals aroundPlants make flowers, fruits, new leaves, cells and stemsAnimals create cells and need to move muscles. Net productivity = Gross productivity - Respiration Energyor using symbols:NP = GP - R

13Net Primary vs. Net Secondary (NPP) vs. (NSP) Calculate Net productivity for plants and animals NPP = GPP RPLANTSNSP = GSP R ANIMALS

NSPNPP14Productivity in Food WebIn a food web diagram, you can assume that:Energy input into an organism represents the GP Energy output from that organism to the next trophic level represents the NPGP-NP = R (respiration energy ) and/or loss to decomposers

?15Measuring Primary ProductivityHarvest method measure biomass and express as biomass per unit area per unit time.CO2 assimilation- measure CO2 uptake in photosynthesis and releases by respiration02 production-Measure O2 production and consumption

16ThereforeThe least productive ecosystems are those with limited heat and light energy, limited water and limited nutrients.Example biome:_______________The most productive ecosystems are those with high temperature, lots of water light and nutrients.Example biome:__________________17Constructing an Energy Flow DiagramTrophic LevelGross Production KJRespiratory Loss KJLoss to decomposersKJProducers50,00020,0005001 Consumer15,00010,0002,000Respiratory loss by decomposer---2,000---18Now check you have understood! Draw a complete food web for an ecosystem of your choice, which should include:the sun and its energynamed primary producers (at least 2)named primary consumers (at least 3)named secondary consumers (at least 2)named decomposers (at least 2)respiration energy loss (use red marker for this arrow)On your diagram use arrows to show direction of energy flow

19Complete this energy flow diagram: Label GPP, NPP and R for the primary producerAdd arrows to show missing energy pathways (5 in total)Fill in the blank box to explain why some sunlight is not fixed by plant

SUNPLANTDECOMPOSERSRESPIRATION.(~98% of energy is here)HERBIVORESDraw your own energy flow diagram, rather like the one on the previous slide to show energy flows through the trophic levels in your food web. Include the following labels:Start with sunlight energyInclude all trophic levels from your food webInclude arrows showing energy moving from each trophic level to another and to decomposersShow energy lost in faecesShow Respiration loss (heat energy) USE RED MARKER!Label each individual arrow with a letter (A,B,C,D,E)Use the lettered arrows to write an equation for GPP, NPPWrite an equation for GSP, NSP for primary consumersThe data in the table below relate to the transfer of energy in a small clearly defined habitat. The units in each case are in kJ m-2 yr-1Construct an energy flow model to represent all these data Label each arrow with the appropriate amount from the data table above.Use boxes to represent each trophic level and arrows to show the flow of energyCalculate the Net Productivity forNPP for ProducersNSP for 1Consumers, 2Consumers, 3ConsumersNSP for DecomposersTrophic LevelGross ProductionRespiratory LossLoss to decomposersProducers60724361204771 Consumer217621470030722 Consumer714576423 Consumer741Respiratory loss by decomposers---3120---

ProducersHerbivores1st. CarnivoresTop CarnivoresDecomposers60724R=3612047721762R=147003072714R=576427R=41R=3120ENERGY FLOW MODELNPP of Producers:60724 -(36120+477)=24127 kJ.m-2.yr-1NSP of 1 Consumer21762-(14700+3072)=3990 kJ.m-2.yr-1NSP of Decomposers:(477+3072+42+1)-3120=472 kJ.m-2.yr-1NSP of 2 Consumer714-(576+42)=96 kJ.m-2.yr-1NSP of 3 Consumer7-(4+1)=2 kJ.m-2.yr-1NSP of Consumers:22483-(15280+3115)=4088 kJ.m-2.yr-1Productivity Calculations