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Sun
Heat
Primary producers
Primaryconsumers
Detritus
Secondary andtertiary
consumers
Microorganismsand other
detritivores
Key
Chemical cycling
Energy flow
4
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Measures of Production
GPP: Gross Primary Production(energy converted to chemical energy of organic compounds in a given amount of time)
NPP: Net Primary Production(includes only GPP not used for respiration in the producers)
NPP = GPP – Ra
NEP: Net Ecosystem Production(total accumulation of biomass)
NEP = GPP – RT
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Technique
Snow
Clouds
Vegetation
Soil
Liquid water
Per
cen
t re
flec
tan
ce
Wavelength (nm)
Visible Near-infrared
400 600 800 1,000 1,2000
20
40
60
80
6
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Net primary production(kg carbon/m2 • yr)
3
2
1
0
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Results
Ammoniumenriched
Phosphateenriched
Unenrichedcontrol
Collection siteA B C D E F G
0
6
12
18
24
30P
hyt
op
lan
kto
n d
ensi
ty(m
illi
on
s o
f ce
lls
per
mL
)
8
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1,400
1,200
1,000
800
600
400
200
0 20 20040 60 80 100 120 140 160 180
Mean annual precipitation (cm)
Net
an
nu
al p
rim
ary
pro
du
ctio
n(a
bo
ve g
rou
nd
, d
ry g
/m2 •
yr)
10
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Plant materialeaten by caterpillar
Cellularrespiration
Growth (new biomass;secondary production)
Not assimilated
Feces100 J
200 J
33 J
67 J
Assimilated
11
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Tertiaryconsumers
Secondaryconsumers
Primaryconsumers
Primaryproducers
10 J
100 J
1,000 J
10,000 J
1,000,000 J of sunlight
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Trophic level
Tertiary consumersSecondary consumers
Primary consumersPrimary producers
(a) Most ecosystems (data from a Florida bog)
(b) Some aquatic ecosystems (data from the English Channel)
Trophic level Dry mass(g/m2)
Dry mass(g/m2)
1.51137
809
421Primary consumers (zooplankton)
Primary producers (phytoplankton)
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Experiment Ecosystem typeArcticSubarcticBorealTemperateGrasslandMountain
A
Results
G
M
TS
U N
H,I
L
B,C
E,F
K
D P
OJ
RQ
P
U
T
RQ
S
OKJ
NM
LI
HGEBA
CD F
8070605040302010
0−15 −10 −5 0 5 10 15
Mean annual temperature (°C)
Per
cen
t o
f m
ass
lo
st
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Movement overland by wind
Precipitationover land
Percolationthroughsoil
Evaporationfrom ocean
Evapotranspirationfrom land
Precipitationover ocean
Runoff andgroundwater
The water cycle
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Consumers
Consumers
Decomposition
Photosynthesis
Cellularrespiration
Photo-synthesis
Phyto-plankton
CO2 inatmosphere
Burning offossil fuelsand wood
The carbon cycle16
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The nitrogen cycle
Fixation
Denitrification
Runoff
N fertilizers
Reactive Ngases
Industrialfixation
N2 inatmosphere
NO3−
NH4
Dissolvedorganic NNO3
−
Aquaticcycling
Decompositionand
sedimentation
Terrestrialcycling
Fixationin root
nodules
Decom-position
N2
NO3−
NH4
Ammoni-fication
Assimilation
Denitri-fication
Uptake ofamino acids
Nitrification
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Wind-blowndust
Geologicuplift
Weatheringof rocks
Decomposition
Plankton Dissolved
Uptake Leaching
Decomposition
Consumption
Runoff
PO43−
Plantuptakeof PO4
3−
Sedimentation
The phosphorus cycle
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Concrete damand weir
(b) Clear-cut watershed
(a)
(c) Nitrate in runoff from watersheds
Deforested
Control
Completion oftree cutting
196819671966196501234
20406080
Nit
rate
co
nc
en
tra
tio
nin
ru
no
ff (
mg
/L)
19
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(a) In 1991, before restoration In 2000, near the completion ofrestoration
(b)
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Decrease in concentration of soluble uraniumin groundwater
(b)Wastes containing uranium, Oak RidgeNational Laboratory
(a)
6
5
4
3
2
1
00 50 100 150 200 250 300 350 400
Days after adding ethanol
Co
nce
ntr
ati
on
of
solu
ble
ura
niu
m (M
)
21