UV and Insect eyesPowerPoint PresentationSpectrumFate of intercepted light?Fate of leaf intercepted light?Fig. 5.4AbsorptionLeaf area indexLeaf Area Index LAILAIs of different canopy typesLight levels and LAILight LevelsLight levels: year profilePhotosynthetic TermsPS terms expandedLCPShade –tolerantShade -intolerantShade and SeedlingsApply your SmartsApply your SmartsSlide 22Leafs and LightShade-Sun leafPS and TemperaturePS and TemperaturePS and tempPlants and TemperatureSlide 29Temperature and plantsPhotosynthesisLight AbsorptionPS Activity ProblemLight ProblemSlide 35PS ProblemFates of reactantsMovement of waterUV and Insect eyesUV and Insect eyesLIGHT&PHOTOSYNTHESISPHOTOSYNTHESISSpectrumSpectrumFate of intercepted Fate of intercepted light?light?Reflect Transmit AbsorbFate of leaf intercepted light?Fate of leaf intercepted light?Reflect - (6-12% PAR, 70% infrared, 3% UV) Degree of reflection varies with type of leaf surfaceTransmit - average 10-20% (primarily green and far red)What would influence this? thickness and structure of leaf Absorb – What does this depend upon?Fig. 5.4Fig. 5.4AbsorptionAbsorptionWhat determines how much light a plant or a group of plants will intercept?Quantity and position of leavesLeaf area indexLeaf area indexLeaf Area IndexLAIInterpretation of LAI see fig 5.5 (d) pg 47 (m2 leaf area/m2 ground area)LAI 3 means 3m2 leaf area over each m2 of groundLAIs of different canopy typesLAIs of different canopy typesSummer Temperate Deciduous Forest: LAI 3-5 (1-5% light hitting canopy reaches floor)Summer Pine Forest LAI 2-4 (10-15% light hitting canopy reaches floor)Tropical Rain ForestLAI 6-10 (.25 – 2% light reaches floor)Light levels and LAILight levels and LAIWhy is the amount of light reaching the forest floor of the pine forest greater than that of the deciduous forest?Does the LAI of an area change throughout the year?What are the consequences of this for plants of the forest floor?Light LevelsLight LevelsAre there other factors other than LAI and leaf angle that would influence the amount of light a forest floor organism might receive? See Fig. 5.7 page 49Light levels: year profileLight levels: year profilePhotosynthetic TermsPAR – photosynthetically active radiationLight compensation point (LCP)Light saturation point (LSP)photoinhibitionPS terms expandedPS terms expandedLight compensation point: rate of C02 uptake in PS = rate of C02 loss in Respiration Short version rate of PS = rate of respirationLight Saturation Point – Point at which increasing light does not increase PSPhotoinhibition - High light levels inhibit PSLCPLCPShade –tolerantShade –tolerantLow PS ratesLow respiration ratesLow metabolic ratesLow growth ratesShade -intolerantShade -intolerantHigher PS ratesHigher respiratory ratesHigher growth ratesLower survival in shade conditionsShade and Shade and SeedlingsSeedlingsApply your SmartsApply your SmartsHow does the concentration of Rubisco relate to photosynthesis rate?What does the production of Rubisco have to do with respiration?What do respiration rates have to do with tolerance to shade?Apply your SmartsApply your SmartsWhat do respiration rates have to do with the light compensation point?What does the light compensation point have to do with shade tolerance or intolerance?In general what types of plants would you expect to have a lower light saturation point: shade inotlerant or shade tolerant Why?Apply your SmartsApply your SmartsWhat would you change in a plant that would increase or lower the light compensation point? Plant a shade intolerant plant in the shade. What would the plant do to compensate for being in low light?Leafs and LightLeafs and LightHow does the amount of light a leaf receives influence its shape and sizE? See page 52 And what does surface area and volume have to do with it?Shade-Sun leafShade-Sun leafPS and TemperaturePS and TemperatureSee page 59 Fig. 6.3-6.4PS and TemperaturePS and TemperaturePS and PS and temptempPlants and TemperaturePlants and TemperatureHeat gain and loss – What are the parameters?Reflectivity of leaf and barkOrientation of leaves to sun and wind?Size and shape of leaves Frost hardiness – Transpiration cooooooling………Plants and TemperaturePlants and Temperature Frost hardiness – mostly geneticAddition of protective compounds (antifreeze type) allows super coolingIce forms in the cell wall???? Transpiration cooooooling………Temperature and plantsTemperature and plantsPhotosynthesisLight AbsorptionPS Activity Problem PS Activity Problem Relative PS activity100%0%Wavelength400 500 600 700Light ProblemLight ProblemRelative Absorbency100%0%Wavelength (nm)400 500 600 700A B C DPhotosynthesisPhotosynthesis6CO2 + 12 H20 ---> C6H12O6 + 6H20 + 602OR6CO2 + 6 H20 ---> C6H12O6 + 602PS ProblemPS ProblemIf you put a plant in a closed container with an atmosphere of 14C02, and H2180 where would you find the radioactive carbon and the heavy oxygen (180) in the container and/or plant?Fates of reactantsFates of reactantsC02H20C6H120602H20H20Movement of waterMovement of