《生态学》课程PPT教学课件（生态学原理与应用）03 Individuals - energy and nutrient relations

IndivdualsEnergyandnatrientrelationsIndividualsENERGYANDNUTRIENTRELATIONS

Individuals Energy and nutrient relations ENERGY AND NUTRIENT RELATIONS Individuals

IndiidualsEnergy andnutrientrelationsxOrganismsone ofthreeusemain sourcesofenergy : lightorganic molecules, or inorganicmolecules.TFEECEOr

Individuals Energy and nutrient relations ❖ Organisms use one of three main sources of energy : light, organic molecules, or inorganic molecules

IndividualsEnergyandnutrientrelationsHeterotrophiePhotosyntheticChemosyntheticBacteriaBacteria draw on a greatervariety of energy sources thanProtistsany other group of organisms.Protists include manyPlantsheterotrophic andphotosyntheticspecies·Autotrophs(self-feeders)Plants are mainly photosynthetic,Fungiwith a fewheterotrophic speciesPhotosynthetic,chemosyntheticFungi and animalsAnimalsHeterotrophs(other-feeders)Trophic(feeding)biologyFIGURE6.2Trophic diversity across the biological kingdoms

Individuals Energy and nutrient relations • Autotrophs(self-feeders) Photosynthetic , chemosynthetic • Heterotrophs(other-feeders) Trophic(feeding) biology

IndivdualsEnergyandnutrientrelationsUsing Light and CO2

Individuals Energy and nutrient relations ➢ Using Light and CO2

IndividualsEnergyandnutrientrelations.Wave, photon.infraredvisiblelight(<400nm),light(400-700nm), ultraviolet light·Photosyntheticlly active radiationPAR.·(solar energy:53% infrared light, 45% visible light, 2%ultraviolet light)Photon flux density(number of photos μumol /m?.s)

Individuals Energy and nutrient relations •Wave, photon •infrared light(<400nm), visible light(400-700nm), ultraviolet light. •Photosyntheticlly active radiation, PAR. •(solar energy: 53% infrared light, 45% visible light, 2% ultraviolet light) •Photon flux density(number of photos mol /m2 .s)

IndividualsEnergyandnatrientrelationsMeasuring PAR100%Boreal forests10%reflect about10%0fincomingPAR79%發福The canopy absorbs79%OfPARPlants in the middlelayersabsorb anadditional 7ofPARLow vegetationOnlyabout2%of PARabsorbs aboutshining on the canopy2%OfPARreaches the forest floorFIGURE6.3Photosyntheticallyactive radiationPARina borealforest(datafromLarcher1995.afterKairiukstis1967)

Individuals Energy and nutrient relations • Measuring PAR

IndividualsEnergyandnutrientrelationsLeaf cross sectionC,plantEpidermal cellMesophyll cellBundle sheath cellVeinsPhotosynthesis takes placeISOAlternative Photosynthetic PathwaysmesophyllO1heleavesofCplants.Mesophyll cellPGACODuringpynthCacidcombineswithRuBPtoform(PGA.)an organic acidRuBPcontaining three carbon atoms.Thefinal products ofphotosynthesis are sugarSugars,molecules,which maybestarchcombinedtoformstarchGURE6.4C,photosynthesis

Individuals Energy and nutrient relations • Alternative Photosynthetic Pathways C3

IndividualsEnergyandnutrientrelationsNCGuOnEpidermal cellMesophyll cellBundlesheathcellC4VeinStomaThe Caacid diffuses to abundle sheath cell.whereInthemesophyll cellsofitbreaks down to pyruvateleaves,Cplantscombineandco,PEPwithCO,toformanorganicacid containingfourcarbon atoms.Mesophyll cellBundle sheath cellChacidCyacidPEPcarboxylaseCOSPEPCOPGAPyruvateCacidBecausethe enzymeRuBPPEPcarboxylasehasahigh affinity for CO2Cplants needtoopenSugars,fewerstomata totakeinstarchsufficientCO,CO,concentrated in thePyruvate diffuses back tobundle sheath cell by thethe bundle sheath cell tobreakdown oftheCyacidformPEP,startingthecombineswithRuBptocyele over againform PGA.FIGURE6.5Caphotosvnthesis

Individuals Energy and nutrient relations C4

IndividualsEnergyandnatrientrelationsDayEpidermal cellEpidermalcellStomaStomaCAM plintsopen theirCAM plants olose thcirstomuta and take instomata during the day.CO,atnightwhenwhentemperatures aretemperatures are lowerhigh and humidity low.and humidity higherMesophyllcellMesophyll cellArnighr CAMplantsCaacids synthesized atcombine PEPwith COnight break downto form four-curbonduring the day toorganic acidspyruvate and cO2Mesophyll cellMesophyll cellNightDayCracidCaacidAPEPCO.PyruvateCo,PGARuBPSugars,starchPyruvate builtup duringCOaconcentrated inthethe day is converted tocellbythebreakdownofPEP,whichcombinesthe C, ncid combineswith Co,thenextnight,withRuBptoformPGAstarting thedaly cyeleoveragain.CAMUREG.GCrasxulaceanacidmerabolism,orCAM.photosynthesix

Individuals Energy and nutrient relations CAM

IndivdualsEnergyandnatrientrelationsC3 plants: lose 380-900g of water for agram(dryweight) of tissue producedCf:250-350gCAM: 50+/-

Individuals Energy and nutrient relations C3 plants: lose 380-900g of water for a gram(dry weight) of tissue produced C4 : 250-350g CAM: 50+/-