Productivity and Food Webs - For Robyn
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1 Lecture 18 Productivity and Lecture 18 Productivity and Food Webs Food Webs Photosynthesis and Respiration on ecosystem Photosynthesis and Respiration on ecosystem scales scales Analysis of global productivity Analysis of global productivity Energy flow through Energy flow through trophic trophic levels and levels and ecosystems ecosystems Three weeks in the life of a food web (DVD) Three weeks in the life of a food web (DVD) World Net Primary Productivity (Rounded Estimates) Ecosystem NPP (g m -2 y -1 ) World NPP (x10 15 g y -1 ) Biomass (g m -2 ) World Biomass (x10 15 g ) Desert 80 0.5 720 15 Grassland, etc. 500 18 4000 125 Cultivated Land 760 8 1000 14 Moist Forest 1000 12 30,000 900 Tropical Forest 2000 18 45,000 750 LAND TOTAL 1804 Estuaries 2000 3 1500 2.6 Continental Shelf 500 5 20 .3 Open Ocean 100 40 3 1.0 MARINE TOTAL 48 3.9 World NPP = NPP × ∑Area World Biomass = Biomass × ∑Area 56 10 15 g = 1 Gigaton see Fig. 55.4 see Fig. 55.4 in your text in your text book book World Net Primary Productivity (Rounded Estimates) Ecosystem NPP (g m -2 y -1 ) World NPP (x10 15 g y -1 ) Biomass (g m -2 ) World Biomass (x10 15 g ) Desert 80 0.5 720 15 Grassland, etc. 500 18 4000 125 Cultivated Land 760 8 1000 14 Moist Forest 1000 12 30,000 900 Tropical Forest 2000 18 45,000 750 LAND TOTAL 1804 Estuaries 2000 3 1500 2.6 Continental Shelf 500 5 20 .3 Open Ocean 100 40 3 1.0 MARINE TOTAL 48 3.9 World NPP = NPP × ∑Area World Biomass = Biomass × ∑Area 56 World Net Primary Productivity (Rounded Estimates) Ecosystem NPP (g m -2 y -1 ) World NPP (x10 15 g y -1 ) Biomass (g m -2 ) World Biomass (x10 15 g ) Desert 80 0.5 720 15 Grassland, etc. 500 18 4000 125 Cultivated Land 760 8 1000 14 Moist Forest 1000 12 30,000 900 Tropical Forest 2000 18 45,000 750 LAND TOTAL 1804 Estuaries 2000 3 1500 2.6 Continental Shelf 500 5 20 .3 Open Ocean 100 40 3 1.0 MARINE TOTAL 48 3.9 World NPP = NPP × ∑Area World Biomass = Biomass × ∑Area 56 3.3% 3.3% 65% 65% % of surface % of surface
Transcript of Productivity and Food Webs - For Robyn
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Lecture 18 Productivity andLecture 18 Productivity andFood WebsFood Webs
Photosynthesis and Respiration on ecosystemPhotosynthesis and Respiration on ecosystemscalesscales
Analysis of global productivityAnalysis of global productivity
Energy flow through Energy flow through trophictrophic levels and levels andecosystemsecosystems
Three weeks in the life of a food web (DVD)Three weeks in the life of a food web (DVD)
World Net Primary Productivity(Rounded Estimates)
Ecosystem
NPP (g m-2 y-1)
World NPP (x1015 g y-1)
Biomass (g m-2 )
World Biomass (x1015 g )
Desert 80 0.5 720 15 Grassland, etc. 500 18 4000 125 Cultivated Land 760 8 1000 14 Moist Forest 1000 12 30,000 900 Tropical Forest 2000 18 45,000 750 LAND TOTAL
1804
Estuaries 2000 3 1500 2.6 Continental Shelf 500 5 20 .3 Open Ocean 100 40 3 1.0 MARINE TOTAL 48 3.9 World NPP = NPP × ∑Area
World Biomass = Biomass × ∑Area
56
1015g = 1 Gigaton
see Fig. 55.4see Fig. 55.4
in your textin your text
bookbook
World Net Primary Productivity(Rounded Estimates)
Ecosystem
NPP (g m-2 y-1)
World NPP (x1015 g y-1)
Biomass (g m-2 )
World Biomass (x1015 g )
Desert 80 0.5 720 15 Grassland, etc. 500 18 4000 125 Cultivated Land 760 8 1000 14 Moist Forest 1000 12 30,000 900 Tropical Forest 2000 18 45,000 750 LAND TOTAL
1804
Estuaries 2000 3 1500 2.6 Continental Shelf 500 5 20 .3 Open Ocean 100 40 3 1.0 MARINE TOTAL 48 3.9 World NPP = NPP × ∑Area
World Biomass = Biomass × ∑Area
56
World Net Primary Productivity(Rounded Estimates)
Ecosystem
NPP (g m-2 y-1)
World NPP (x1015 g y-1)
Biomass (g m-2 )
World Biomass (x1015 g )
Desert 80 0.5 720 15 Grassland, etc. 500 18 4000 125 Cultivated Land 760 8 1000 14 Moist Forest 1000 12 30,000 900 Tropical Forest 2000 18 45,000 750 LAND TOTAL
1804
Estuaries 2000 3 1500 2.6 Continental Shelf 500 5 20 .3 Open Ocean 100 40 3 1.0 MARINE TOTAL 48 3.9 World NPP = NPP × ∑Area
World Biomass = Biomass × ∑Area
563.3%3.3%
65%65%
% of surface% of surface
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Phytoplankton
BarnacleBlue Crab
Sea Bass
ZooplanktonSea Worms
Shore Birds
Shore Shrimp
Marine Food Web
Photo Source: The Lloyd Center at UMass
Detritus
Flow of Carbon (Energy) Through aFlow of Carbon (Energy) Through aTrophic Level (or organism)Trophic Level (or organism) Rn
InPn -1 PnAn
FnDn
Bn
LivingBiomass
DeadOrganicMatter
Pn-1 = Productivity of trophic level n-1
Dn = Portion of Pn-1 not consumed
In = Amount Ingested
Fn = Fecal matter produced
An = Amount assimilated and available
Rn = Respiration
Bn = Biomass in trophic level n
Pn = Productivity at trophic level n
To DetritusFood Web
TrophicLevel n
Rn
InPn -1 PnAn
FnDn
Bn
LivingBiomass
TrophicLevel n
DeadOrganicMatter To Detritus
Food Web
EfficienciesEfficiencies
Assim ilat ion Eff iciency (AE)
AE = An / In × 1 0 0
Production Eff iciency (PE)
PE = Pn / An × 1 0 0
Ecological Efficiency = (EE)(AE)(PE)
(trophic transfer efficiency) = Pn / Pn-1 × 100
≈ 10 % to 20 %
Exploitation Eff iciency ( EE)
EE = In / Pn-1 × 1 0 0
Phytoplankton
BarnacleBlue Crab
Sea Bass
ZooplanktonSea Worms
Shore Birds
Shore Shrimp
Marine Food Web
Photo Source: The Lloyd Center at UMass
Detritus
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Phytoplankton
ZooplanktonSea Worms
Shore BirdsMarine Food Web
Photo Source: The Lloyd Center at UMass
Detritus
Grazing Food Web
Microbial Food Web Detrivore Food Web
Net Ecosystem Production= GPP - RA
- ∑ RH
DetrivoresDetrivores
RA RH
RH RH
GPP11stst
carnivorecarnivore
““RefractoryRefractory””CarbonCarbon
RH
RH
Heat
Etc.
Etc.
POCPOCDOCDOC
P
D
AI
D F F
DetritusDetritus
POC = Part iculatePOC = Part iculateOrg anic CarbonOrg anic Carbon
DOC = DissolvedDOC = DissolvedOrg anic CarbonOrg anic Carbon
2nd Carnivore2nd Carnivore
NPP
MicroorganismsMicroorganisms
I APrimary producersPrimary producers
herbivoresherbivores
Grassland
Forest
Open Ocean
Biomass(grams/m2)
Energy Flow(calories/m2/day)
Pyramids of Biomass and Energy
Producers Herbivores Carnivores
Inverted Pyramidof Biomass
Biomass tied up inwood & unavailable
to herbivores
Biomass in greenplants, accessible to
herbivores
See alsoSee alsoFig. 55.7Fig. 55.7in textin text
Photosynthetic Organisms(Our world depends on this for food and fiber)
Respiration
Process:Photosynthesis
Excretion and Death
Respiration
Digestion, assimilation, & growth
Another Representation of Energy FlowThrough an Ecosystem
Detritivores
Herbivores
Primarycarnivores
Secondarycarnivores
The majority of energyis lost to respirationand is unavailable to
other organisms
See alsoSee alsoFig. 55.3 inFig. 55.3 in
texttext
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Respiration
Direct Use
(food, fuel,fiber, timber)
Productive capacity lostby land conversion &desertification oroveruse(open land to cities, foreststo cropland etc.)
Human Appropriation of Photosynthesis
Detritivores
Herbivores
Primarycarnivores
Secondarycarnivores
Diverted Productivity
(crop waste, lumberwaste, burning etc)
Small%largest%
Medium%
Between 10 and 55% has been appropriated(difficult to estimate)
Take Home MessagesTake Home Messages Massive amounts of carbon flow through photosynthesisMassive amounts of carbon flow through photosynthesis
each yeareach year
Marine and Terrestrial ecosystems Marine and Terrestrial ecosystems roughlyroughly same amount same amount
Carbon/energy flows through food websCarbon/energy flows through food webs
80-90% dissipated with each 80-90% dissipated with each trophictrophic transfer transfer
In mature ecosystems, nearly all that is produced is eatenIn mature ecosystems, nearly all that is produced is eaten
Humans have co-opted a significant fraction of globalHumans have co-opted a significant fraction of globalprimary productivityprimary productivity
Blue Planet DVDBlue Planet DVDThree weeks in the life of aThree weeks in the life of a
Marine Food WebMarine Food WebThink About:Think About:
•• The massive amount of energy andThe massive amount of energy andcarbon the phytoplankton must becarbon the phytoplankton must beprocessing to support such a diversity andprocessing to support such a diversity andbiomass at higher biomass at higher trophictrophic levels levels
•• How the information in DNA could beHow the information in DNA could becontrolling all of these complex processescontrolling all of these complex processes
