18-Ecosystem Energy Movement_student.pptx - Movement of...

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Movement of Energy in Ecosystems
Lesson objectives Understand how energy moves through an ecosystem Describe different ways to measure productivity Compare net productivity among different ecosystems Understand how nutrients can affect productivity Calculate trophic efficiencies
Solar energy powers photosynthesis of producers Few ecosystems use chemical energy for chemosynthesis Producers form base of food webs The sun is the ultimate source of energy for most ecosystems 1% of solar energy is captured
Gross primary productivity (GPP) rate that energy is captured and assimilated by producers Energy used for respiration, growth, reproduction Net primary productivity (NPP) rate that energy is assimilated into producer biomass Standing crop NPP = GPP - respiration Primary productivity is the rate at which energy is converted into organic compounds in producers GPP = 2.5 kg C/m 2 /yr Respiration = 1.5 kg C/m 2 /yr NPP = 1 kg C/m 2 /yr
How can primary productivity be quantified? Producer biomass Remote sensing Uptake/Release of CO 2 or O 2 Light-dark bottle experiments NPP = net CO 2 GPP = net CO 2 + respired CO 2 Terrestrial vs Aquatic NPP = net O 2 GPP = net O 2 + respired O 2 NPP = GPP - respiration GPP - R + GPP - R GPP = NPP + respiration R

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