a term em- phasizing that the cycles of chemical...
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T
Ch
ap
ter 58
Dyn
am
ics
of E
cosy
stem
s
Intr
od
uc
tio
n
Th
e E
art
h is
a r
ela
tive
ly c
lose
d s
yste
m w
ith
re
spe
ct t
o c
he
mic
als
. It
is a
n o
pe
n s
yste
m in
te
rms
of
en
erg
y, h
ow
eve
r, b
eca
use
it r
ece
ive
s e
ne
rgy
at
vis
ible
an
d n
ea
r-v
isib
le w
ave
len
gth
s fr
om
th
e S
un
an
d s
tea
dil
y e
mit
s th
erm
al e
ne
rgy
to o
ute
r sp
ace
in
the
fo
rm o
f in
fra
red
ra
dia
tio
n. T
he
org
an
ism
s in
eco
syst
em
s in
tera
ct in
co
mp
lex
wa
ys a
s th
ey
pa
rtic
ipa
te in
th
e c
ycli
ng
of
che
mic
als
an
d a
s th
ey
cap
ture
an
d e
xpe
nd
en
erg
y. A
ll o
rga
nis
ms,
incl
ud
ing
hu
ma
ns,
de
pe
nd
on
th
e s
pe
cia
lize
d a
bil
itie
s
of
oth
er
org
an
ism
s—p
lan
ts, a
lga
e, a
nim
als
, fu
ng
i, a
nd
pro
kary
ote
s—to
acq
uir
e t
he
ess
en
tia
ls o
f li
fe, a
s e
xpla
ine
d in
th
is
cha
pte
r. In
ch
ap
ters
58
an
d 5
9, w
e c
on
sid
er
the
ma
ny
dif
fere
nt
typ
es
of
eco
syst
em
s th
at
con
stit
ute
th
e b
iosp
he
re a
nd
dis
cuss
the
th
rea
ts t
o t
he
bio
sph
ere
an
d t
he
sp
eci
es
it c
on
tain
s.
Ch
ap
ter
Ou
tlin
e
58
.1
Bio
geo
chem
ical
Cyc
les
58
.2
Th
e F
low
of
En
erg
y in
Eco
syst
ems
58
.3
Tro
ph
ic-L
evel
In
tera
ctio
ns
58
.4
Bio
div
ersi
ty a
nd
Eco
syst
em S
tab
ilit
y
58
.5
Isla
nd
Bio
geo
gra
ph
y
CH
AP
TE
R
Apago PDF Enhancer
CO
2 in a
tmosphere
Dis
solv
ed C
O2 a
nd
HC
O3-
Carb
on in a
lgae
and p
lants
C
arb
on in
anim
als
Exchange
betw
een
wate
r and
atm
osphere
Carb
on in d
ead
org
anic
matt
er C
arb
on in
fossil
fuels
(c
oal, p
etr
ole
um
)
Carb
on in
anim
als
Carb
on in
pla
nts
Rele
ase
of
meth
ane
Oxid
ation
of
meth
ane
Mic
robia
lR
espirationAnim
al
Respiration
Pla
nt
Respiration
Photo
synth
esis
Com
bustion o
f fu
els
in
industr
y, h
om
es,
and c
ars
Fo
od
ch
ain
s
Ph
oto
syn
thesis
Resp
irati
on
Co
nvers
ion
by g
eo
log
ical
pro
cesses
Fo
od
ch
ain
s
Fig
ure
58
.1 T
he
ca
rbo
n c
ycl
e.
Ph
oto
syn
thes
is
by
pla
nts
an
d a
lgae
cap
ture
s ca
rbo
n i
n t
he
form
of
org
anic
ch
emic
al c
om
po
un
ds.
Aer
ob
ic
resp
irat
ion
by
org
anis
ms
and
fu
el
com
bu
stio
n b
y h
um
ans
retu
rn
carb
on
to
th
e fo
rm o
f ca
rbo
n
dio
xid
e (C
O2)
or
bic
arb
on
ate
(HC
O32 )
.
Mic
rob
ial
met
han
og
ens
livi
ng
in o
xyg
en-f
ree
mic
roh
abit
ats,
su
ch a
s
the
mu
d a
t th
e
bo
tto
m o
f th
e p
on
d,
mig
ht
pro
du
ce
met
han
e (C
H4),
a g
as
that
wo
uld
en
ter
the
atm
osp
her
e an
d t
hen
gra
du
ally
be
oxi
diz
ed
abio
tica
lly
to c
arb
on
dio
xid
e (s
ho
wn
in
gre
en
circ
led
in
set)
.
you
r li
fe t
o c
on
tain
a c
arb
on
or
oxy
gen
ato
m t
hat
on
ce w
as p
art
of
Juli
us
Cae
sar’
s b
od
y o
r C
leo
pat
ra’s
.
Th
e at
om
s o
f th
e va
rio
us
chem
ical
ele
men
ts a
re s
aid
to
m
ove
th
rou
gh
eco
syst
ems
in b
iog
eoch
emic
al c
ycle
s, a
ter
m e
m-
ph
asiz
ing
th
at t
he
cycl
es o
f ch
emic
al e
lem
ents
in
volv
e n
ot
on
ly
bio
log
ical
org
anis
ms
and
pro
cess
es, b
ut
also
geo
log
ical
(ab
ioti
c)
syst
ems
and
pro
cess
es. B
iog
eoch
emic
al c
ycle
s in
clu
de
pro
cess
es
that
occ
ur
on
man
y sp
atia
l sc
ales
, fr
om
cel
lula
r to
pla
net
ary,
an
d t
hey
als
o i
ncl
ud
e p
roce
sses
th
at o
ccu
r o
n m
ult
iple
tim
e-sc
ales
, fr
om
se
con
ds
(bio
chem
ical
re
acti
on
s)
to
mil
len
nia
(w
eath
erin
g o
f ro
cks)
.
Bio
geo
chem
ical
cyc
les
usu
ally
cro
ss t
he
bo
un
dar
ies
of
eco
syst
ems
to s
om
e ex
ten
t, r
ath
er t
han
bei
ng
sel
f-co
nta
ined
w
ith
in
ind
ivid
ual
ec
osy
stem
s.
Fo
r ex
amp
le,
on
e ec
osy
stem
m
igh
t im
po
rt o
r ex
po
rt c
arb
on
to
oth
ers.
In
th
is s
ecti
on
, we
con
sid
er t
he
cycl
es o
f so
me
maj
or
ele-
men
ts a
lon
g w
ith
th
e co
mp
ou
nd
wat
er. W
e al
so p
rese
nt
an e
x-am
ple
of
bio
geo
chem
ical
cyc
les
in a
fo
rest
eco
syst
em.
Ca
rbo
n, t
he
ba
sis
of
org
an
ic c
om
po
un
ds,
cycl
es
thro
ug
h m
ost
eco
syst
em
s
Car
bo
n i
s a
maj
or
con
stit
uen
t o
f th
e b
od
ies
of
org
anis
ms
bec
ause
car
bo
n a
tom
s h
elp
fo
rm t
he
fram
ewo
rk o
f al
l o
r-g
anic
co
mp
ou
nd
s (s
ee c
hap
ter
3);
alm
ost
20
% o
f th
e w
eig
ht
of
the
hu
man
bo
dy
is c
arb
on
. Fro
m t
he
view
po
int
of
the
day
-to
-day
dyn
amic
s o
f ec
osy
stem
s, c
arb
on
dio
xid
e (C
O2)
is t
he
mo
st s
ign
ific
ant
carb
on
-co
nta
inin
g c
om
po
un
d i
n t
he
abio
tic
envi
ron
men
ts o
f o
rgan
ism
s. I
t m
akes
up
0.0
3%
of
the
vol-
um
e o
f th
e at
mo
sph
ere,
mea
nin
g t
he
atm
osp
her
e co
nta
ins
abo
ut
75
0 b
illi
on
met
ric
ton
s o
f ca
rbo
n.
In a
qu
atic
eco
sys-
tem
s, C
O2 r
eact
s sp
on
tan
eou
sly
wit
h t
he
wat
er t
o f
orm
bi-
carb
on
ate
ion
s (H
CO
3–).
58
.1
Bio
geo
chem
ica
l Cyc
les
Le
arn
ing
Ou
tco
me
s
De
fin
e e
cosy
ste
m.
1.
List
fo
ur
che
mic
als
wh
ose
cyc
lic
inte
ract
ion
s a
re c
riti
cal
2.
to o
rga
nis
ms.
De
scri
be
ho
w h
um
an
act
ivit
ies
dis
rup
t th
ese
cyc
les.
3.
An
eco
syst
em in
clu
des
all
th
e o
rgan
ism
s th
at li
ve in
a p
arti
cula
r p
lace
, p
lus
the
abio
tic
(no
nli
vin
g)
envi
ron
men
t in
wh
ich
th
ey
live
—an
d w
ith
wh
ich
th
ey i
nte
ract
—at
th
at l
oca
tio
n.
Eco
sys-
tem
s ar
e in
trin
sica
lly
dyn
amic
in
a n
um
ber
of
way
s, i
ncl
ud
ing
th
eir
pro
cess
ing
of
mat
ter
and
en
erg
y. W
e st
art
wit
h m
atte
r.
Th
e a
tom
ic c
on
stit
ue
nts
of
ma
tte
r
cycl
e w
ith
in e
cosy
ste
ms
Du
rin
g t
he
bio
log
ical
pro
cess
ing
of
mat
ter,
th
e at
om
s o
f w
hic
h
it is
co
mp
ose
d, s
uch
as
the
ato
ms
of
carb
on
or
oxy
gen
, mai
nta
in
thei
r in
teg
rity
eve
n a
s th
ey a
re a
ssem
ble
d i
nto
new
co
mp
ou
nd
s an
d t
he
com
po
un
ds
are
late
r b
roke
n d
ow
n.
Th
e E
arth
has
an
es
sen
tial
ly f
ixed
nu
mb
er o
f ea
ch o
f th
e ty
pes
of
ato
ms
of
bio
-lo
gic
al i
mp
ort
ance
, an
d t
he
ato
ms
are
recy
cled
.
Eac
h o
rgan
ism
ass
emb
les
its
bo
dy
fro
m a
tom
s th
at p
revi
-o
usl
y w
ere
in t
he
soil
, th
e at
mo
sph
ere,
oth
er p
arts
of
the
abio
tic
envi
ron
men
t, o
r o
ther
org
anis
ms.
Wh
en t
he
org
anis
m d
ies,
its
at
om
s ar
e re
leas
ed u
nal
tere
d t
o b
e u
sed
by
oth
er o
rgan
ism
s o
r re
turn
ed t
o t
he
abio
tic
envi
ron
men
t. B
ecau
se o
f th
e cy
clin
g o
f th
e at
om
ic c
on
stit
uen
ts o
f m
atte
r, y
ou
r b
od
y is
lik
ely
du
rin
g
12
08
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
Gaseous w
ate
r (w
ate
r vapor)
in
the
atm
osphere
Perc
ola
tion t
hro
ugh s
oil
Wate
r in
th
e o
ceans
Gro
undw
ate
r
Wate
r in
lakes
and r
ivers
Dro
ple
tw
ate
r
Evapora
tion
Evapora
tion
Flo
w o
f ri
vers
to t
he s
ea
Pre
cip
itation
Condensation
Tra
nspiration
Pre
cip
itation
Pre
cip
itation
Fig
ure
58
.2 T
he
wa
ter
cy
cle
. W
ater
cir
cula
tes
fro
m
the
atm
osp
her
e to
th
e su
rfac
e o
f th
e E
arth
an
d b
ack
agai
n. T
he
Su
n p
rovi
des
mu
ch o
f th
e en
erg
y
req
uir
ed f
or
evap
ora
tio
n.
rap
idly
th
an o
ther
s. T
hes
e d
iffe
ren
ces
in r
ate
hav
e o
rdin
aril
y b
een
rel
ativ
ely
mi-
no
r o
n a
yea
r-to
-yea
r b
asis
; in
an
y o
ne
year
, th
e am
ou
nt
of
CO
2 m
ade
by
bre
akd
ow
n o
f o
rgan
ic
com
po
un
ds
alm
ost
mat
ches
th
e am
ou
nt
of
CO
2 u
sed
to
sy
nth
esiz
e n
ew o
rgan
ic c
om
po
un
ds.
S
mal
l mis
mat
ches
, ho
wev
er, c
an h
ave
larg
e co
nse
qu
ence
s if
co
nti
nu
ed f
or
man
y ye
ars.
Th
e E
arth
’s p
rese
nt
rese
rves
of
coal
wer
e b
uil
t u
p o
ver
geo
log
ic t
ime.
Org
anic
co
mp
ou
nd
s su
ch a
s ce
llu
lose
acc
um
ula
ted
by
bei
ng
syn
thes
ized
fas
ter
than
th
ey w
ere
bro
ken
do
wn
, an
d t
hen
th
ey w
ere
tran
sfo
rmed
by
geo
log
ical
pro
cess
es i
nto
th
e fo
ssil
fu
els.
Mo
st s
cien
tist
s b
e-li
eve
that
th
e w
orl
d’s
pet
role
um
res
erve
s w
ere
crea
ted
in
th
e sa
me
way
.
Hu
man
bu
rnin
g o
f fo
ssil
fu
els
tod
ay is
cre
atin
g la
rge
con
-te
mp
ora
ry i
mb
alan
ces
in t
he
carb
on
cyc
le.
Car
bo
n t
hat
to
ok
mil
lio
ns
of
year
s to
acc
um
ula
te i
n t
he
rese
rves
of
foss
il f
uel
s is
b
ein
g r
apid
ly r
etu
rned
to
th
e at
mo
sph
ere,
dri
vin
g t
he
con
cen
-tr
atio
n o
f C
O2 i
n t
he
atm
osp
her
e u
pw
ard
yea
r b
y ye
ar a
nd
h
elp
ing
to
sp
ur
fear
s o
f g
lob
al w
arm
ing
(se
e ch
apte
r 5
9).
Th
e a
va
ila
bil
ity
of
wa
ter
is f
un
da
me
nta
l
to t
err
est
ria
l eco
syst
em
s
Th
e w
ater
cyc
le, s
een
in f
igu
re 5
8.2
, is
pro
bab
ly t
he
mo
st f
amil
-ia
r o
f al
l b
iog
eoch
emic
al c
ycle
s. A
ll l
ife
dep
end
s o
n t
he
pre
s-en
ce o
f w
ater
; eve
n o
rgan
ism
s th
at c
an s
urv
ive
wit
ho
ut
wat
er in
re
stin
g s
tate
s re
qu
ire
wat
er t
o r
egai
n a
ctiv
ity.
Th
e b
od
ies
of
mo
st o
rgan
ism
s co
nsi
st m
ain
ly o
f w
ater
. Th
e ad
ult
hu
man
bo
dy,
fo
r ex
amp
le, i
s ab
ou
t 6
0%
wat
er b
y w
eig
ht.
Th
e am
ou
nt
of
wa-
ter
avai
lab
le i
n a
n e
cosy
stem
oft
en d
eter
min
es t
he
nat
ure
an
d
abu
nd
ance
of
the
org
anis
ms
pre
sen
t, a
s il
lust
rate
d b
y th
e d
iffe
r-en
ce b
etw
een
fo
rest
s an
d d
eser
ts (
see
chap
ter
59
).
Eac
h t
ype
of
bio
geo
chem
ical
cyc
le h
as d
isti
nct
ive
fea-
ture
s. A
dis
tin
ctiv
e fe
atu
re o
f th
e w
ater
cyc
le i
s th
at w
ater
is
a co
mp
ou
nd
, no
t an
ele
men
t, a
nd
th
us
it c
an b
e sy
nth
esiz
ed a
nd
b
roke
n d
ow
n.
It i
s sy
nth
esiz
ed d
uri
ng
aer
ob
ic c
ellu
lar
resp
ira-
tio
n (
see
chap
ter
7)
and
ch
emic
ally
sp
lit
du
rin
g p
ho
tosy
nth
esis
(s
ee c
hap
ter
8).
Th
e ra
tes
of t
hes
e p
roce
sses
are
ord
inar
ily
abo
ut
equ
al,
and
th
eref
ore
a r
elat
ivel
y co
nst
ant
amo
un
t o
f w
ater
cy-
cles
th
rou
gh
th
e b
iosp
her
e.
Th
e b
asi
c ca
rbo
n c
ycle
Th
e ca
rbo
n c
ycle
is
stra
igh
tfo
rwar
d, a
s sh
ow
n i
n f
igu
re 5
8.1
. In
te
rres
tria
l ec
osy
stem
s, p
lan
ts a
nd
oth
er p
ho
tosy
nth
etic
org
an-
ism
s tak
e in
CO
2 fr
om
the
atm
osp
her
e an
d u
se it
in p
ho
tosy
nth
esis
to
sy
nth
esiz
e th
e ca
rbo
n-c
on
tain
ing
org
anic
co
mp
ou
nd
s o
f w
hic
h t
hey
are
co
mp
ose
d (
see
chap
ter
8).
Th
e p
roce
ss i
s so
me-
tim
es c
alle
d c
arbo
n fix
atio
n ; f
ixat
ion
ref
ers
to m
etab
oli
c re
acti
on
s th
at m
ake
no
ngas
eou
s co
mp
ou
nd
s fr
om
gas
eou
s o
nes
.
An
imal
s ea
t th
e p
ho
tosy
nth
etic
org
anis
ms
and
bu
ild
th
eir
ow
n t
issu
es b
y m
akin
g u
se o
f th
e ca
rbo
n a
tom
s in
th
e o
rgan
ic
com
po
un
ds
they
in
gest
. Bo
th t
he
ph
oto
syn
thet
ic o
rgan
ism
s an
d
the
anim
als
ob
tain
en
ergy
du
rin
g th
eir
live
s b
y b
reak
ing
do
wn
so
me
of th
e o
rgan
ic c
om
po
un
ds
avai
lab
le t
o t
hem
, th
rou
gh a
ero
-b
ic c
ellu
lar
resp
irat
ion
(se
e ch
apte
r 7)
. Wh
en t
hey
do
th
is, th
ey
pro
du
ce C
O2.
Dec
ayin
g o
rgan
ism
s al
so p
rod
uce
CO
2. C
arb
on
at
om
s re
turn
ed t
o t
he
form
of
CO
2 ar
e av
aila
ble
on
ce m
ore
to
be
use
d in
ph
oto
syn
thes
is t
o s
ynth
esiz
e n
ew o
rgan
ic c
om
po
un
ds.
In
aq
uat
ic e
cosy
stem
s, t
he
carb
on
cyc
le i
s fu
nd
amen
tall
y si
mil
ar,
exce
pt
that
in
org
anic
car
bo
n i
s p
rese
nt
in t
he
wat
er
no
t o
nly
as
dis
solv
ed C
O2,
bu
t al
so a
s H
CO
3– i
on
s, b
oth
of
wh
ich
act
as
sou
rces
of
carb
on
fo
r p
ho
tosy
nth
esis
by
alg
ae a
nd
aq
uat
ic p
lan
ts.
Me
tha
ne
pro
du
cers
Mic
rob
es t
hat
bre
ak d
ow
n o
rgan
ic c
om
po
un
ds
by
anae
rob
ic
cell
ula
r re
spir
atio
n (
see
chap
ter
7)
pro
vid
e an
ad
dit
ion
al d
imen
-si
on
to
th
e glo
bal
car
bo
n c
ycle
. Met
han
ogen
s, f
or
exam
ple
, are
m
icro
bes
th
at p
rod
uce
met
han
e (C
H4)
inst
ead
of
CO
2. O
ne
ma-
jor
sou
rce
of
CH
4 i
s w
etla
nd
eco
syst
ems,
wh
ere
met
han
ogen
s li
ve i
n t
he
oxy
gen
-fre
e se
dim
ents
. M
eth
ane
that
en
ters
th
e at
-m
osp
her
e is
oxi
diz
ed a
bio
tica
lly
to C
O2, b
ut
CH
4 t
hat
rem
ain
s is
ola
ted
fro
m o
xygen
can
per
sist
fo
r gre
at l
ength
s o
f ti
me.
Th
e r
ise
of
atm
osp
he
ric
carb
on
dio
xid
e
An
oth
er d
imen
sio
n o
f th
e g
lob
al c
arb
on
cyc
le i
s th
at o
ver
lon
g
stre
tch
es o
f ti
me,
so
me
par
ts o
f th
e cy
cle
may
pro
ceed
mo
re
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
20
9w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
Fig
ure
58
.3 D
efo
rest
ati
on
dis
rup
ts t
he
lo
cal
wa
ter
cy
cle
. T
rop
ical
def
ore
stat
ion
can
hav
e se
vere
co
nse
qu
ence
s, s
uch
as t
he
exte
nsi
ve e
rosi
on
in
th
is a
rea
in t
he
Am
azo
n r
egio
n o
f B
razi
l.
25
mya
. S
tart
ing
at
abo
ut
that
tim
e, m
ou
nta
ins
such
as
Mo
un
t K
ilim
anja
ro r
ose
up
bet
wee
n t
he
rain
fo
rest
s an
d t
he
Ind
ian
O
cean
, th
eir
sou
rce
of
mo
istu
re.
Th
e p
rese
nce
of
the
mo
un
-ta
ins
forc
ed w
ind
s fr
om
th
e In
dia
n O
cean
up
war
d, c
oo
lin
g t
he
air
and
cau
sin
g m
uch
of
its
mo
istu
re t
o p
reci
pit
ate
bef
ore
th
e ai
r re
ach
ed t
he
rain
fo
rest
s. T
he
lan
d b
ecam
e m
uch
dri
er,
and
th
e fo
rest
s tu
rned
to
gra
ssla
nd
s.
To
day
, hu
man
act
ivit
ies
can
alt
er t
he
wat
er c
ycle
so
pro
-fo
un
dly
th
at m
ajo
r ch
ang
es o
ccu
r in
eco
syst
ems.
Ch
ang
es i
n
rain
fo
rest
s ca
use
d b
y d
efo
rest
atio
n p
rovi
de
an e
xam
ple
. In
h
ealt
hy
tro
pic
al r
ain
fo
rest
s, m
ore
th
an 9
0%
of
the
mo
istu
re
that
fal
ls a
s ra
in i
s ta
ken
up
by
pla
nts
an
d r
etu
rned
to
th
e ai
r b
y tr
ansp
irat
ion
. P
lan
ts,
in a
ver
y re
al s
ense
, cr
eate
th
eir
ow
n
rain
: T
he
mo
istu
re r
etu
rned
to
th
e at
mo
sph
ere
fall
s b
ack
on
th
e fo
rest
s.
Wh
en h
um
an p
op
ula
tio
ns
cut
do
wn
or
bu
rn t
he
rain
fo
r-es
ts in
an
are
a, t
he
loca
l wat
er c
ycle
is b
roke
n. W
ater
th
at f
alls
as
rain
th
erea
fter
dra
ins
away
in
riv
ers
inst
ead
of
risi
ng t
o f
orm
cl
ou
ds
and
fal
l agai
n o
n t
he
fore
sts.
Ju
st s
uch
a t
ran
sfo
rmat
ion
is
occ
urr
ing t
od
ay in
man
y tr
op
ical
rai
n fo
rest
s (f
igu
re 5
8.3
). L
arge
area
s in
Bra
zil,
for
exam
ple
, wer
e tr
ansf
orm
ed i
n t
he
20th
cen
-tu
ry f
rom
lush
tro
pic
al f
ore
st t
o s
emia
rid
des
ert,
dep
rivi
ng m
any
un
iqu
e p
lan
t an
d a
nim
al s
pec
ies
of
thei
r n
ativ
e h
abit
at.
Th
e n
itro
ge
n c
ycl
e d
ep
en
ds
on
nit
rog
en
" x
ati
on
by
mic
rob
es
Nit
rog
en i
s a
com
po
nen
t o
f al
l p
rote
ins
and
nu
clei
c ac
ids
and
is
req
uir
ed i
n s
ub
stan
tial
am
ou
nts
by
all
org
anis
ms;
pro
tein
s ar
e 1
6%
nit
rog
en b
y w
eig
ht.
In
man
y ec
osy
stem
s, n
itro
gen
is
the
chem
ical
ele
men
t in
sh
ort
est
sup
ply
rel
ativ
e to
th
e n
eed
s o
f o
rgan
ism
s. A
par
ado
x is
th
at t
he
atm
osp
her
e is
78
% n
itro
gen
b
y vo
lum
e.
Th
e b
asi
c w
ate
r cy
cle
On
e ke
y p
art
of
the
wat
er c
ycle
is
that
liq
uid
wat
er f
rom
th
e E
arth
’s s
urf
ace
evap
ora
tes
into
th
e at
mo
sph
ere.
Th
e ch
ang
e o
f w
ater
fro
m a
liq
uid
to
a g
as r
equ
ires
a c
on
sid
erab
le a
dd
itio
n o
f th
erm
al e
ner
gy,
exp
lain
ing
wh
y ev
apo
rati
on
occ
urs
mo
re r
ap-
idly
wh
en s
ola
r ra
dia
tio
n b
eats
do
wn
on
a s
urf
ace.
E
vap
ora
tio
n o
ccu
rs d
irec
tly
fro
m t
he
surf
aces
of
oce
ans,
la
kes,
an
d r
iver
s. I
n t
erre
stri
al e
cosy
stem
s, h
ow
ever
, ap
pro
xi-
mat
ely
90
% o
f th
e w
ater
th
at r
each
es t
he
atm
osp
her
e p
asse
s th
rou
gh
pla
nts
. T
rees
, g
rass
es,
and
oth
er p
lan
ts t
ake
up
wat
er
fro
m s
oil
via
th
eir
roo
ts,
and
th
en t
he
wat
er e
vap
ora
tes
fro
m
thei
r le
aves
an
d o
ther
su
rfac
es t
hro
ug
h a
pro
cess
cal
led
tra
nsp
i-ra
tio
n (
see
chap
ter
38
).
Eva
po
rate
d w
ater
exi
sts
in t
he
atm
osp
her
e as
a g
as,
just
li
ke a
ny
oth
er a
tmo
sph
eric
gas
. T
he
wat
er c
an c
on
den
se b
ack
into
liq
uid
fo
rm, h
ow
ever
, mo
stly
bec
ause
of
coo
lin
g o
f th
e ai
r.
Co
nd
ensa
tio
n o
f g
aseo
us
wat
er (
wat
er v
apo
r) i
nto
dro
ple
ts o
r cr
ysta
ls c
ause
s th
e fo
rmat
ion
of
clo
ud
s, a
nd
if
the
dro
ple
ts o
r cr
ysta
ls a
re la
rge
eno
ug
h, t
hey
fal
l to
th
e su
rfac
e o
f th
e E
arth
as
pre
cip
itat
ion
(ra
in o
r sn
ow
).
Gro
un
dw
ate
r
Les
s o
bvi
ou
s th
an s
urf
ace
wat
er,
wh
ich
we
see
in r
iver
s an
d
lake
s, i
s w
ater
un
der
gro
un
d—
term
ed g
rou
nd
wat
er.
Gro
un
d-
wat
er o
ccu
rs i
n a
qu
ifers
, w
hic
h a
re p
erm
eab
le,
un
der
gro
un
d
laye
rs o
f ro
ck,
san
d,
and
gra
vel
that
are
oft
en s
atu
rate
d w
ith
w
ater
. G
rou
nd
wat
er i
s th
e m
ost
im
po
rtan
t re
serv
oir
of
wat
er
on
lan
d i
n m
any
par
ts o
f th
e w
orl
d,
rep
rese
nti
ng
ove
r 9
5%
of
all
fres
h w
ater
in
th
e U
nit
ed S
tate
s, f
or
exam
ple
.
Go
un
dw
ater
co
nsi
sts
of
two
su
bp
arts
. Th
e u
pp
er l
ayer
s o
f th
e gro
un
dw
ater
co
nst
itu
te t
he
wat
er t
able
, wh
ich
is u
nco
nfi
ned
in
th
e se
nse
th
at i
t fl
ow
s in
to s
trea
ms
and
is
par
tly
acce
ssib
le t
o
the
roo
ts o
f p
lan
ts.
Th
e lo
wer
, co
nfi
ned
lay
ers
of
the
gro
un
d-
wat
er a
re g
ener
ally
ou
t o
f re
ach
to
str
eam
s an
d p
lan
ts,
bu
t ca
n
be
tap
ped
by
wel
ls. G
rou
nd
wat
er is
rec
har
ged
by
wat
er t
hat
per
-co
late
s d
ow
nw
ard
fro
m a
bo
ve, s
uch
as
fro
m p
reci
pit
atio
n. W
ater
in
an
aq
uif
er f
low
s m
uch
mo
re s
low
ly t
han
su
rfac
e w
ater
, an
y-w
her
e fr
om
a f
ew m
illi
met
ers
to a
met
er o
r so
per
day
.
In t
he
Un
ited
Sta
tes,
gro
un
dw
ater
pro
vid
es a
bo
ut
25
% o
f th
e w
ater
use
d b
y h
um
ans
for
all p
urp
ose
s, a
nd
it s
up
pli
es a
bo
ut
50
% o
f th
e p
op
ula
tio
n w
ith
dri
nki
ng
wat
er. I
n t
he
Gre
at P
lain
s st
ates
, th
e d
eep
Og
alla
la A
qu
ifer
is t
app
ed e
xten
sive
ly a
s a
wat
er
sou
rce
for
agri
cult
ura
l an
d d
om
esti
c n
eed
s. T
he
aqu
ifer
is b
ein
g
dep
lete
d f
aste
r th
an i
t is
rec
har
ged
—a
loca
l im
bal
ance
in
th
e w
ater
cyc
le—
po
sin
g a
n o
min
ou
s th
reat
to
th
e ag
ricu
ltu
ral
pro
-d
uct
ion
of
the
area
. S
imil
ar t
hre
ats
exis
t in
man
y o
f th
e d
rier
p
ort
ion
s o
f th
e g
lob
e.
Ch
an
ge
s in
eco
syst
em
s b
rou
gh
t a
bo
ut
by
ch
an
ge
s in
th
e w
ate
r cy
cle
Wat
er i
s so
cru
cial
fo
r li
fe t
hat
ch
ang
es i
n i
ts s
up
ply
in
an
ec
osy
stem
can
rad
ical
ly a
lter
th
e n
atu
re o
f th
e ec
osy
stem
. S
uch
ch
ang
es h
ave
occ
urr
ed o
ften
du
rin
g t
he
Ear
th’s
geo
log
i-ca
l h
isto
ry.
C
on
sid
er,
for
exam
ple
, th
e ec
osy
stem
of
the
Ser
eng
eti
Pla
in i
n T
anza
nia
, fa
mo
us
for
its
seem
ing
ly e
nd
less
gra
ssla
nd
s o
ccu
pie
d b
y va
st h
erd
s o
f an
telo
pes
an
d o
ther
gra
zin
g a
nim
als.
T
he
sem
iari
d g
rass
lan
ds
of
tod
ay’s
Ser
eng
eti
wer
e ra
in f
ore
sts
12
10
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
N2 in
atm
osphere
Nitro
gen in
anim
al tissues
Rele
ase
of
am
monia
by s
oil
Nitro
gen in
pla
nt
tissues
Soil
NH
3 a
nd N
O3
:U
rea
Nitro
gen in
tissues o
f alg
ae
and p
lants
Nitro
gen in
anim
al tissues
Dis
solv
ed N
H3 a
nd N
O3
:
Upta
ke
by r
oots
Nitro
gen f
ixation b
ysoil
mic
robes
Food
chain
s
Excre
tion
Decom
positio
nD
ecom
positio
n
Mic
robia
l m
eta
bolis
m
Nitro
gen f
ixation
by a
qu
ati
ccyan
ob
acte
ria
Acti
vit
y o
fd
en
itri
fyin
g m
icro
bes
An
imal
excre
tio
no
f N
H3
Gro
wth
Fo
od
ch
ain
s
Fig
ure
58
.4 T
he
nit
rog
en
cy
cle
. T
he
nit
rog
en c
ycle
is
com
pli
cate
d b
ecau
se i
t
invo
lves
mu
ltip
le c
han
ges
in
th
e ch
emic
al
form
of
nit
rog
en. C
erta
in
pro
kar
yote
s &
x at
mo
sph
eric
nit
rog
en (
N2)
, co
nve
rtin
g i
t to
form
s su
ch a
s am
mo
nia
(NH
3) a
nd
nit
rate
(N
O3–)
that
pla
nts
an
d a
lgae
can
use
. O
ther
pro
kar
yote
s
retu
rn n
itro
gen
to
th
e
atm
osp
her
e as
N2 b
y
bre
akin
g d
ow
n
NH
3 o
r o
ther
nit
rog
en-c
on
tain
ing
com
po
un
ds.
Am
mo
nia
,
a g
as, ca
n e
nte
r th
e
atm
osp
her
e d
irec
tly
fro
m s
oil
s.
term
nit
roge
n fi
xati
on t
o r
efer
sp
ecif
ical
ly t
o t
his
ste
p. A
fter
NH
3
has
bee
n s
ynth
esiz
ed,
oth
er p
roka
ryo
tic
mic
rob
es o
xid
ize
par
t o
f it
to
fo
rm N
O3–, a
pro
cess
cal
led
nit
rifi
cati
on
.
Cer
tain
gen
era
of
pro
kary
ote
s h
ave
the
abil
ity
to a
cco
m-
pli
sh n
itro
gen
fix
atio
n u
sin
g a
sys
tem
of
enzy
mes
kn
ow
n a
s th
e n
itro
gen
ase
com
ple
x (t
he
nif
gen
e co
mp
lex;
see
ch
apte
r 28).
M
ost
of t
he
mic
rob
es a
re fr
ee-l
ivin
g, b
ut
on
lan
d s
om
e ar
e fo
un
d
in s
ymb
ioti
c re
lati
on
ship
s w
ith
th
e ro
ots
of
legu
mes
(p
lan
ts o
f th
e p
ea f
amil
y, F
abac
eae)
, ald
ers,
myr
tles
, an
d o
ther
pla
nts
.
Ad
dit
ion
al p
roka
ryo
tic
mic
rob
es (
incl
ud
ing
bo
th b
acte
ria
and
arc
hae
a) a
re a
ble
to
co
nve
rt t
he
nit
rog
en i
n N
O3– i
nto
N2
(or
oth
er
nit
rog
en
gas
es
such
as
N
2O
),
a p
roce
ss
term
ed
den
itri
fica
tio
n.
Am
mo
nia
can
be
sub
ject
ed t
o d
enit
rifi
cati
on
in
dir
ectl
y b
y b
ein
g c
on
vert
ed f
irst
to
NO
3– a
nd
th
en t
o N
2.
Nit
rog
en
ou
s w
ast
es
an
d f
ert
iliz
er
use
Mo
st a
nim
als,
wh
en t
hey
bre
ak d
ow
n p
rote
ins
in t
hei
r m
etab
o-
lism
, ex
cret
e th
e n
itro
gen
fro
m t
he
pro
tein
s as
NH
3.
Hu
man
s an
d o
ther
mam
mal
s ex
cret
e n
itro
gen
as
ure
a in
th
eir
uri
ne
(see
ch
apte
r 5
1);
a n
um
ber
of
typ
es o
f m
icro
bes
co
nve
rt t
he
ure
a to
N
H3.
Th
e N
H3 f
rom
an
imal
exc
reti
on
can
be
pic
ked
up
by
pla
nts
an
d a
lgae
as
a so
urc
e o
f n
itro
gen
.
Hu
man
po
pu
lati
on
s ar
e ra
dic
ally
alt
erin
g t
he
glo
bal
ni-
tro
gen
cyc
le b
y th
e u
se o
f fe
rtil
izer
s o
n l
awn
s an
d a
gri
cult
ura
l fi
eld
s. T
he
fert
iliz
ers
con
tain
fo
rms
of
fixe
d n
itro
gen
th
at c
rop
s ca
n u
se, s
uch
as
amm
on
ium
(N
H4)
salt
s m
anu
fact
ure
d in
du
stri
-al
ly f
rom
atm
osp
her
ic N
2.
Par
tly
bec
ause
of
the
pro
du
ctio
n o
f fe
rtil
izer
s, h
um
ans
hav
e al
read
y d
ou
ble
d t
he
rate
of
tran
sfer
of
N2 i
n u
sab
le f
orm
s in
to s
oil
s an
d w
ater
s.
Nit
rog
en
av
ail
ab
ilit
y
Ho
w c
an n
itro
gen
be
in s
ho
rt s
up
ply
if
the
atm
osp
her
e is
so
ri
ch w
ith
it?
Th
e an
swer
is
that
th
e n
itro
gen
in
th
e at
mo
sph
ere
is i
n i
ts e
lem
enta
l fo
rm—
mo
lecu
les
of
nit
rog
en g
as (
N2)—
and
th
e va
st m
ajo
rity
of
org
anis
ms,
incl
ud
ing
all
pla
nts
an
d a
nim
als,
h
ave
no
way
to
use
nit
rog
en i
n t
his
ch
emic
al f
orm
.
Fo
r an
imal
s, t
he
ult
imat
e so
urc
e o
f n
itro
gen
is
nit
rog
en-
con
tain
ing
org
anic
co
mp
ou
nd
s sy
nth
esiz
ed b
y p
lan
ts o
r b
y al
-g
ae o
r o
ther
mic
rob
es.
Her
biv
oro
us
anim
als,
fo
r ex
amp
le,
eat
pla
nt
or
alg
al p
rote
ins
and
use
th
e n
itro
gen
-co
nta
inin
g a
min
o
acid
s in
th
em t
o s
ynth
esiz
e th
eir
ow
n p
rote
ins.
P
lan
ts
and
al
gae
u
se
a n
um
ber
o
f si
mp
le
nit
rog
en-
con
tain
ing
co
mp
ou
nd
s as
th
eir
sou
rces
of
nit
rog
en t
o s
ynth
e-si
ze p
rote
ins
and
oth
er n
itro
gen
-co
nta
inin
g o
rgan
ic c
om
po
un
ds
in t
hei
r ti
ssu
es. T
wo
co
mm
on
ly u
sed
nit
rog
en s
ou
rces
are
am
-m
on
ia (
NH
3)
and
nit
rate
io
ns
(NO
3–).
As
des
crib
ed i
n c
hap
ter
39
, ce
rtai
n p
roka
ryo
tic
mic
rob
es c
an s
ynth
esiz
e am
mo
nia
an
d
nit
rate
fro
m N
2 i
n t
he
atm
osp
her
e, t
her
eby
con
stit
uti
ng
a p
art
of
the
nit
rog
en c
ycle
th
at m
akes
atm
osp
her
ic n
itro
gen
acc
essi
-b
le t
o p
lan
ts a
nd
alg
ae (
fig
ure
58
.4) .
Oth
er p
roka
ryo
tes
turn
N
H3 a
nd
NO
3– i
nto
N2, m
akin
g t
he
nit
rog
en i
nac
cess
ible
. Th
e b
alan
ce o
f th
e ac
tivi
ties
of
thes
e tw
o s
ets
of
mic
rob
es d
eter
-m
ines
th
e ac
cess
ibil
ity
of
nit
rog
en t
o p
lan
ts a
nd
alg
ae.
Mic
rob
ial n
itro
ge
n f
ixa
tio
n, n
itri
fica
tio
n,
an
d d
en
itri
fica
tio
n
Th
e sy
nth
esis
of
nit
rog
en-c
on
tain
ing
co
mp
ou
nd
s fr
om
N2 i
s kn
ow
n a
s n
itro
gen
fix
atio
n. T
he
firs
t st
ep in
th
is p
roce
ss is
th
e sy
nth
esis
of
NH
3 f
rom
N2, a
nd
bio
chem
ists
so
met
imes
use
th
e
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
21
1w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
Phosphate
s in
solu
tion
Phosphate
s in
anim
al tissues E
xcre
tio
nS
olu
ble
phosphate
sin
soil
Phosphate
s in
rocks a
nd m
iner a
ls
Weath
eri
ng
Deco
mp
osit
ion
Phosphate
s in
pla
nt
tissues
Fo
od
ch
ain
s
Lo
ss i
n d
rain
ag
e
Pre
cip
itati
on
Phosphate
s in
pla
nt
tissues
Phosphate
s in
anim
al tissues
Excre
tio
n a
nd
deco
mp
osit
ion
Food
chain
s
Up
take
by r
oo
ts
Phosphate
s in s
edim
ent
Up
take
by r
oo
ts
Fig
ure
58
.5 T
he
ph
osp
ho
rus
cy
cle
. In
co
ntr
ast
to
carb
on
, w
ater
, an
d n
itro
gen
, p
ho
sph
oru
s o
ccu
rs
on
ly i
n t
he
liq
uid
an
d s
oli
d s
tate
s an
d t
hu
s d
oes
no
t en
ter
the
atm
osp
her
e.
oth
er p
ote
nti
al c
ulp
rit
in a
dd
ing
PO
43
– t
o e
cosy
stem
s, b
ut
law
s n
ow
man
dat
e lo
w-p
ho
sph
ate
det
erg
ents
in
mu
ch o
f th
e w
orl
d.
Lim
itin
g n
utr
ien
ts in
eco
syst
em
s a
re t
ho
se
in s
ho
rt s
up
ply
re
lati
ve
to
ne
ed
A c
hai
n i
s o
nly
as
stro
ng
as
its
wea
kest
lin
k. F
or
the
pla
nts
an
d
alg
ae in
an
eco
syst
em t
o g
row
—an
d t
o t
her
eby
pro
vid
e fo
od
fo
r an
imal
s—th
ey n
eed
man
y d
iffe
ren
t ch
emic
al e
lem
ents
. T
he
sim
ple
st t
heo
ry is
th
at in
an
y p
arti
cula
r ec
osy
stem
, on
e el
emen
t w
ill
be
in s
ho
rtes
t su
pp
ly r
elat
ive
to t
he
nee
ds
for
it b
y th
e p
lan
ts a
nd
alg
ae.
Th
at e
lem
ent
is t
he
lim
itin
g n
utr
ien
t—th
e w
eak
lin
k—in
th
e ec
osy
stem
.
Th
e cy
cle
of
a li
mit
ing
nu
trie
nt
is p
arti
cula
rly
imp
ort
ant
bec
ause
it
det
erm
ines
th
e ra
te a
t w
hic
h t
he
nu
trie
nt
is m
ade
avai
lab
le f
or
use
. We
gav
e th
e n
itro
gen
an
d p
ho
sph
oru
s cy
cles
cl
ose
att
enti
on
pre
cise
ly b
ecau
se t
ho
se e
lem
ents
are
th
e li
mit
-in
g n
utr
ien
ts i
n m
any
eco
syst
ems.
Nit
rog
en i
s th
e li
mit
ing
n
utr
ien
t in
ab
ou
t tw
o-t
hir
ds
of
the
oce
ans
and
in
man
y te
rres
-tr
ial
eco
syst
ems.
O
cean
ogra
pher
s h
ave
disc
over
ed in
just
th
e la
st 1
5 ye
ars
that
ir
on i
s th
e lim
itin
g n
utri
ent
for
alga
l po
pula
tion
s (p
hyt
opla
nkt
on)
in a
bout
on
e-th
ird
of t
he
wor
ld’s
ocea
ns.
In
th
ese
wat
ers,
win
d-bo
rne
soil
dust
see
ms
ofte
n t
o be
th
e ch
ief
sour
ce o
f ir
on. W
hen
w
ind
brin
gs i
n i
ron
-ric
h d
ust,
alga
l po
pula
tion
s pr
olif
erat
e, p
ro-
vide
d th
e ir
on is
in a
usa
ble
chem
ical
form
. In
th
is w
ay, s
and
stor
ms
in t
he
Sah
ara
Des
ert,
by i
ncr
easi
ng
the
dust
in
glo
bal
win
ds,
can
in
crea
se a
lgal
pro
duct
ivit
y in
Pac
ific
wat
ers
(fig
ure
58.6
).
Bio
ge
och
em
ica
l cy
clin
g in
a f
ore
st e
cosy
ste
m
ha
s b
ee
n s
tud
ied
ex
pe
rim
en
tall
y
An
on
go
ing
ser
ies
of
stu
die
s at
th
e H
ub
bar
d B
roo
k E
xper
imen
-ta
l F
ore
st i
n N
ew H
amp
shir
e h
as y
ield
ed m
uch
of
the
avai
lab
le
info
rmat
ion
ab
ou
t th
e cy
clin
g o
f n
utr
ien
ts in
fo
rest
eco
syst
ems.
Ph
osp
ho
rus
cycl
es
thro
ug
h
terr
est
ria
l an
d a
qu
ati
c e
cosy
ste
ms,
bu
t n
ot
the
atm
osp
he
re
Ph
osp
ho
rus
is r
equ
ired
in s
ub
stan
tial
qu
anti
ties
by
all o
rgan
ism
s;
it o
ccu
rs i
n n
ucl
eic
acid
s, m
emb
ran
e p
ho
sph
oli
pid
s, a
nd
oth
er
esse
nti
al c
om
po
un
ds,
su
ch a
s ad
eno
sin
e tr
iph
osp
hat
e (A
TP
).
Un
like
car
bo
n,
wat
er,
and
nit
rog
en,
ph
osp
ho
rus
has
no
si
gn
ific
ant
gas
eou
s fo
rm a
nd
do
es n
ot
cycl
e th
rou
gh
th
e at
mo
-sp
her
e (f
igu
re 5
8.5
) . I
n t
his
res
pec
t, t
he
ph
osp
ho
rus
cycl
e ex
-em
pli
fies
th
e so
rts
of
cycl
es a
lso
exh
ibit
ed b
y ca
lciu
m,
sili
con
, an
d m
any
oth
er m
iner
al e
lem
ents
. An
oth
er f
eatu
re t
hat
gre
atly
si
mp
lifi
es t
he
ph
osp
ho
rus
cycl
e co
mp
ared
wit
h t
he
nit
rog
en
cycl
e is
th
at p
ho
sph
oru
s ex
ists
in e
cosy
stem
s in
just
a s
ing
le o
xi-
dat
ion
sta
te, p
ho
sph
ate
(PO
43
–).
Ph
osp
ha
te a
va
ila
bil
ity
Pla
nts
an
d a
lgae
use
fre
e in
org
anic
PO
43
– i
n t
he
soil
or
wat
er
for
syn
thes
izin
g
thei
r p
ho
sph
oru
s-co
nta
inin
g
org
anic
co
m-
po
un
ds.
An
imal
s th
en t
ap t
he
ph
osp
ho
rus
in p
lan
t o
r al
gal
tis
-su
e co
mp
ou
nd
s to
bu
ild
th
eir
ow
n p
ho
sph
oru
s co
mp
ou
nd
s.
Wh
en
org
anis
ms
die
, d
ecay
m
icro
bes
—in
a
pro
cess
ca
lled
p
ho
sph
ate
re m
in er
a liz
a tio
n—
bre
ak u
p t
he
org
anic
co
mp
ou
nd
s in
th
eir
bo
die
s, r
elea
sin
g p
ho
sph
oru
s as
in
org
anic
PO
43
– t
hat
p
lan
ts a
nd
alg
ae a
gai
n c
an u
se.
T
he
ph
osp
ho
rus
cycl
e in
clu
des
cri
tica
l ab
ioti
c ch
emic
al
and
ph
ysic
al p
roce
sses
. Fre
e P
O43 – e
xist
s in
so
il in
on
ly lo
w c
on
-ce
ntr
atio
ns
bo
th b
ecau
se i
t co
mb
ines
wit
h o
ther
so
il c
on
stit
u-
ents
to
fo
rm i
nso
lub
le c
om
po
un
ds
and
bec
ause
it
ten
ds
to b
e w
ash
ed a
way
by
stre
ams
and
riv
ers.
Wea
ther
ing o
f m
any
sort
s o
f ro
cks
rele
ases
new
PO
43 – in
to t
erre
stri
al s
yste
ms,
bu
t th
en r
iver
s ca
rry
the
PO
43 – i
nto
th
e o
cean
bas
ins.
Th
ere
is a
lar
ge
on
e-w
ay
flu
x o
f P
O43 – f
rom
ter
rest
rial
ro
cks
to d
eep
-sea
sed
imen
ts.
Ph
osp
ha
tes
as
fert
iliz
ers
Hu
man
act
ivit
ies
hav
e g
reat
ly m
od
ifie
d t
he
glo
bal
ph
osp
ho
rus
cycl
e si
nce
th
e ad
ven
t o
f cr
op
fer
tili
zati
on
. Fer
tili
zers
are
typ
i-ca
lly
des
ign
ed t
o p
rovi
de
PO
43
– b
ecau
se c
rop
s m
igh
t o
ther
wis
e b
e sh
ort
of
it;
the
PO
43
– i
n f
erti
lize
rs i
s ty
pic
ally
der
ived
fro
m
cru
shed
ph
osp
hat
e-ri
ch r
ock
s an
d b
on
es.
Det
erg
ents
are
an
-
12
12
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
Dust
a.
b.
Concentration of nitrate (mg/L)
80
40 4 2 0 1
965
1966
1967
1968
Year
defo
reste
d
wate
rshed
undis
turb
ed
wate
rshed
Defo
resta
tion
Fig
ure
58
.6 O
ne
wo
rld
. E
very
yea
r, m
illi
on
s o
f m
etri
c to
ns
of
iro
n-r
ich
du
st i
s ca
rrie
d w
estw
ard
by
the
trad
e w
ind
s fr
om
th
e
Sah
ara
Des
ert
and
nei
gh
bo
rin
g S
ahel
are
a. A
wo
rkin
g h
yp
oth
esis
of
man
y o
cean
og
rap
her
s is
th
at t
his
du
st f
erti
lize
s p
arts
of
the
oce
an,
incl
ud
ing
par
ts o
f th
e P
aci&
c O
cean
, w
her
e ir
on
is
the
lim
itin
g
nu
trie
nt.
Lan
d u
se p
ract
ices
in
Afr
ica,
wh
ich
are
in
crea
sin
g t
he
size
of
the
no
rth
Afr
ican
des
ert,
can
th
us
affe
ct e
cosy
stem
s o
n t
he
oth
er
sid
e o
f th
e g
lob
e.
Fig
ure
58
.7 T
he
Hu
bb
ard
Bro
ok
ex
pe
rim
en
t. a
. A
38
-acr
e w
ater
shed
was
co
mp
lete
ly d
efo
rest
ed, an
d t
he
run
off
mo
nit
ore
d f
or
seve
ral
year
s. b
. D
efo
rest
atio
n g
reat
ly i
ncr
ease
d t
he
loss
of
nu
trie
nts
in
ru
no
ff w
ater
fro
m t
he
eco
syst
em. T
he
ora
ng
e cu
rve
sho
ws
the
nit
rate
con
cen
trat
ion
in
th
e ru
no
ff w
ater
fro
m t
he
def
ore
sted
wat
ersh
ed;
the
gre
en c
urv
e sh
ow
s th
e n
itra
te c
on
cen
trat
ion
in
ru
no
ff w
ater
fro
m a
n
un
dis
turb
ed n
eigh
bo
rin
g w
ater
shed
.
Hu
bb
ard
Bro
ok
is t
he
cen
tral
str
eam
of
a la
rge
wat
ersh
ed t
hat
d
rain
s th
e h
ills
ides
of
a m
ou
nta
in r
ang
e co
vere
d w
ith
tem
per
ate
dec
idu
ou
s fo
rest
. Mu
ltip
le t
rib
uta
ry s
trea
ms
carr
y w
ater
off
th
e h
ills
ides
in
to H
ub
bar
d B
roo
k.
Six
tri
bu
tary
str
eam
s, e
ach
dra
inin
g a
par
ticu
lar
vall
ey,
wer
e eq
uip
ped
wit
h m
easu
rem
ent
dev
ices
wh
en t
he
stu
dy
was
st
arte
d.
All
of
the
wat
er t
hat
flo
wed
ou
t o
f ea
ch v
alle
y h
ad t
o
pas
s th
rou
gh
th
e m
easu
rem
ent
syst
em, w
her
e th
e fl
ow
of
wat
er
and
co
nce
ntr
atio
ns
of
nu
trie
nts
was
qu
anti
fied
.
Th
e u
nd
istu
rbed
fo
rest
s ar
ou
nd
Hu
bb
ard
Bro
ok
are
ef-
fici
ent
at r
etai
nin
g n
utr
ien
ts. I
n a
yea
r, o
nly
sm
all
qu
anti
ties
of
nu
trie
nts
en
ter
a va
lley
fro
m o
uts
ide,
do
ing
so
mo
stly
as
a re
-su
lt o
f p
reci
pit
atio
n. T
he
qu
anti
ties
car
ried
ou
t in
str
eam
wa-
ters
are
sm
all
also
. Wh
en w
e sa
y “s
mal
l,” w
e m
ean
th
e in
flu
xes
and
o
utf
luxe
s re
pre
sen
t ju
st
min
or
frac
tio
ns
of
the
tota
l am
ou
nts
of
nu
trie
nts
in
th
e sy
stem
—ab
ou
t 1
% i
n t
he
case
of
calc
ium
, fo
r ex
amp
le.
In
196
5 an
d 1
966,
th
e in
vest
igat
ors
fel
led
all
th
e tr
ees
and
cl
eare
d a
ll s
hru
bs
in o
ne
of t
he
six
vall
eys
and
pre
ven
ted
reg
row
th
(fig
ure
58.
7a). T
he
effe
cts
wer
e d
ram
atic
. Th
e am
ou
nt
of
wat
er
run
nin
g o
ut
of
that
val
ley
incr
ease
d b
y 40
%, i
nd
icat
ing
that
wa-
ter
pre
vio
usl
y ta
ken
up
by
vege
tati
on
an
d e
vap
ora
ted
in
to t
he
atm
osp
her
e w
as n
ow
ru
nn
ing
off
. Th
e am
ou
nts
of
a n
um
ber
of
nu
trie
nts
ru
nn
ing
ou
t o
f th
e sy
stem
als
o g
reat
ly i
ncr
ease
d.
Fo
r ex
amp
le, t
he
rate
of
loss
of
calc
ium
incr
ease
d n
inef
old
. Ph
osp
ho
-ru
s, o
n t
he
oth
er h
and
, d
id n
ot
incr
ease
in
th
e st
ream
wat
er;
it
app
aren
tly
was
lo
cked
up
in
in
solu
ble
co
mp
ou
nd
s in
th
e so
il.
T
he
chan
ge
in t
he
stat
us
of
nit
rog
en i
n t
he
dis
turb
ed v
al-
ley
was
esp
ecia
lly
stri
kin
g (
fig
ure
58
.7b)
. Th
e u
nd
istu
rbed
fo
r-es
t in
th
is v
alle
y h
ad b
een
acc
um
ula
tin
g N
O3– a
t a
rate
of
abo
ut
5 k
g p
er h
ecta
re p
er y
ear,
bu
t th
e d
efo
rest
ed e
cosy
stem
lo
st
NO
3– a
t a
rate
of
abo
ut
53
kg
per
hec
tare
per
yea
r. T
he
NO
3–
con
cen
trat
ion
in t
he
stre
am w
ater
rap
idly
incr
ease
d. T
he
fert
il-
ity
of
the
vall
ey d
ecre
ased
dra
mat
ical
ly,
wh
ile
the
run
-off
of
nit
rate
gen
erat
ed m
assi
ve a
lgal
blo
om
s d
ow
nst
ream
, an
d t
he
dan
ger
of
do
wn
stre
am f
loo
din
g g
reat
ly i
ncr
ease
d.
T
his
exp
erim
ent
is p
arti
cula
rly
inst
ruct
ive
at t
he
star
t o
f th
e 2
1st
cen
tury
bec
ause
fo
rest
ed l
and
co
nti
nu
es t
o b
e cl
eare
d
wo
rld
wid
e (s
ee c
hap
ter
59
).
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
21
3w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
T
he
seco
nd
pri
nci
ple
is
that
wh
enev
er o
rgan
ism
s u
se
chem
ical
-bo
nd
or
lig
ht
ener
gy,
so
me
of
it i
s co
nve
rted
to
hea
t;
the
Sec
on
d L
aw o
f T
her
mo
dyn
amic
s st
ates
th
at a
par
tial
co
n-
vers
ion
to
hea
t is
inev
itab
le. P
ut
ano
ther
way
, an
imal
s an
d p
lan
ts
req
uir
e ch
emic
al-b
on
d e
ner
gy
and
lig
ht
to s
tay
aliv
e, b
ut
as
they
use
th
ese
form
s o
f en
erg
y, t
hey
co
nve
rt t
hem
to
hea
t,
wh
ich
th
ey c
ann
ot
use
to
sta
y al
ive
and
wh
ich
th
ey c
ann
ot
cycl
e b
ack
into
th
e o
rig
inal
fo
rms.
F
ort
un
atel
y fo
r o
rgan
ism
s, t
he
Ear
th f
un
ctio
ns
as a
n o
pen
sy
stem
fo
r en
erg
y. L
igh
t ar
rive
s ev
ery
day
fro
m t
he
Su
n. P
lan
ts
and
oth
er p
ho
tosy
nth
etic
org
anis
ms
use
th
e n
ewly
arr
ived
lig
ht
to s
ynth
esiz
e o
rgan
ic c
om
po
un
ds
and
sta
y al
ive.
An
imal
s th
en
eat
the
ph
oto
syn
thet
ic o
rgan
ism
s, m
akin
g u
se o
f th
e ch
emic
al-
bo
nd
en
erg
y in
th
eir
org
anic
mo
lecu
les
to s
tay
aliv
e. L
igh
t an
d
chem
ical
-bo
nd
en
erg
y ar
e p
arti
ally
co
nve
rted
to
hea
t at
eve
ry
step
. In
fac
t, t
he
lig
ht
and
ch
emic
al-b
on
d e
ner
gy
are
ult
imat
ely
con
vert
ed c
om
ple
tely
to
hea
t. T
he
hea
t le
aves
th
e E
arth
by
be-
ing
rad
iate
d i
nto
ou
ter
spac
e at
in
visi
ble
, in
frar
ed w
avel
eng
ths
of
the
elec
tro
mag
net
ic s
pec
tru
m. F
or
life
to
co
nti
nu
e, n
ew li
gh
t en
erg
y is
alw
ays
req
uir
ed.
T
he
Ear
th’s
in
com
ing
an
d o
utg
oin
g f
low
s o
f ra
dia
nt
en-
erg
y m
ust
be
equ
al f
or
glo
bal
tem
per
atu
re t
o s
tay
con
stan
t. O
ne
con
cern
is
that
hu
man
act
ivit
ies
are
chan
gin
g t
he
com
po
siti
on
o
f th
e at
mo
sph
ere
in w
ays
that
im
ped
e th
e o
utg
oin
g f
low
—th
e so
-cal
led
gre
enho
use
eff
ect,
wh
ich
is
des
crib
ed i
n t
he
foll
ow
ing
ch
apte
r. H
eat
may
be
accu
mu
lati
ng
on
Ear
th,
cau
sin
g g
lob
al
war
min
g (
see
chap
ter
59
).
En
erg
y #
ow
s th
rou
gh
tro
ph
ic
lev
els
of
eco
syst
em
s
In c
hap
ter
7,
we
intr
od
uce
d t
he
con
cep
ts o
f au
totr
op
hs
(“se
lf-
feed
ers”
) an
d h
eter
otr
op
hs
(“fe
d b
y o
ther
s”).
Au
totr
op
hs
syn
-th
esiz
e th
e o
rgan
ic c
om
po
un
ds
of
thei
r b
od
ies
fro
m i
no
rgan
ic
pre
curs
ors
su
ch a
s C
O2, w
ater
, an
d N
O3– u
sin
g e
ner
gy
fro
m a
n
abio
tic
sou
rce.
So
me
auto
tro
ph
s u
se l
igh
t as
th
eir
sou
rce
of
en-
erg
y an
d t
her
efo
re a
re p
ho
toau
totr
op
hs;
th
ey a
re t
he
ph
oto
-sy
nth
etic
org
anis
ms,
in
clu
din
g p
lan
ts, a
lgae
, an
d c
yan
ob
acte
ria.
O
ther
au
totr
op
hs
are
chem
oau
totr
op
hs
and
ob
tain
en
erg
y b
y m
ean
s o
f in
org
anic
oxi
dat
ion
rea
ctio
ns,
su
ch a
s th
e m
icro
bes
th
at u
se h
ydro
gen
su
lfid
e av
aila
ble
at
dee
p w
ater
ven
ts (
see
chap
ter
59
). A
ll c
hem
oau
totr
op
hs
are
pro
kary
oti
c. T
he
ph
oto
-au
totr
op
hs
are
of
gre
ates
t im
po
rtan
ce i
n m
ost
eco
syst
ems,
an
d
we
focu
s o
n t
hem
in
th
e re
mai
nd
er o
f th
is c
hap
ter.
H
eter
otr
op
hs
are
org
anis
ms
that
can
no
t sy
nth
esiz
e o
r-g
anic
co
mp
ou
nd
s fr
om
ino
rgan
ic p
recu
rso
rs, b
ut
inst
ead
live
by
taki
ng
in
org
anic
co
mp
ou
nd
s th
at o
ther
org
anis
ms
hav
e m
ade.
T
hey
ob
tain
th
e en
erg
y th
ey n
eed
to
liv
e b
y b
reak
ing
up
so
me
of
the
org
anic
co
mp
ou
nd
s av
aila
ble
to
th
em, t
her
eby
lib
erat
ing
ch
emic
al-b
on
d e
ner
gy
for
met
abo
lic
use
(se
e ch
apte
r 7
). A
ni-
mal
s, f
un
gi,
and
man
y m
icro
bes
are
het
ero
tro
ph
s.
Wh
en l
ivin
g i
n t
hei
r n
ativ
e en
viro
nm
ents
, sp
ecie
s ar
e o
f-te
n o
rgan
ized
in
to c
hai
ns
that
eat
eac
h o
ther
seq
uen
tial
ly.
Fo
r ex
amp
le, a
sp
ecie
s o
f in
sect
mig
ht
eat
pla
nts
, an
d t
hen
a s
pec
ies
of
shre
w m
igh
t ea
t th
e in
sect
, an
d a
sp
ecie
s o
f h
awk
mig
ht
eat
the
shre
w. F
oo
d p
asse
s th
rou
gh
th
e fo
ur
spec
ies
in t
he
seq
uen
ce:
pla
nts
→ i
nse
ct →
sh
rew
→ h
awk.
A s
equ
ence
of
spe-
cies
lik
e th
is i
s te
rmed
a f
oo
d c
hai
n.
58
.2
The
Flo
w o
f En
erg
y in
Eco
syst
ems
Le
arn
ing
Ou
tco
me
s
De
scri
be
the
dif
fere
nt
tro
ph
ic le
vels
.1.
Dis
tin
gu
ish
be
twe
en
en
erg
y a
nd
he
at.
2.
Exp
lain
ho
w e
ne
rgy
mo
ves
thro
ug
h t
rop
hic
leve
ls.
3.
Th
e d
ynam
ic n
atu
re o
f ec
osy
stem
s in
clu
des
th
e p
roce
ssin
g o
f en
erg
y as
wel
l as
th
at o
f m
atte
r. E
ner
gy,
ho
wev
er, fo
llo
ws
very
d
iffe
ren
t p
rin
cip
les
than
do
es m
atte
r. E
ner
gy
is n
ever
rec
ycle
d.
Inst
ead
, ra
dia
nt
ener
gy
fro
m t
he
Su
n t
hat
rea
ches
th
e E
arth
m
akes
a o
ne-
way
pas
s th
rou
gh
ou
r p
lan
et’s
eco
syst
ems
bef
ore
b
ein
g c
on
vert
ed t
o h
eat
and
rad
iate
d b
ack
into
sp
ace,
sig
nif
yin
g
that
th
e E
arth
is
an o
pen
sys
tem
fo
r en
erg
y.
En
erg
y c
an
ne
ith
er
be
cre
ate
d
no
r d
est
roy
ed
, bu
t ch
an
ge
s fo
rm
Wh
y is
en
erg
y so
dif
fere
nt
fro
m m
atte
r? A
key
par
t o
f th
e an
-sw
er i
s th
at e
ner
gy
exis
ts i
n s
ever
al d
iffe
ren
t fo
rms,
su
ch a
s li
gh
t, c
hem
ical
-bo
nd
en
erg
y, m
oti
on
, an
d h
eat.
Alt
ho
ug
h e
n-
erg
y is
nei
ther
cre
ated
no
r d
estr
oye
d i
n t
he
bio
sph
ere
(th
e F
irst
Law
of
Th
erm
od
ynam
ics)
, it
freq
uen
tly
chan
ges
fo
rm.
A
sec
on
d k
ey p
oin
t is
th
at o
rgan
ism
s ca
nn
ot
con
vert
hea
t to
an
y o
f th
e o
ther
form
s o
f en
ergy
. Th
us,
if o
rgan
ism
s co
nve
rt s
om
e ch
emic
al-b
on
d o
r li
ght
ener
gy t
o h
eat,
th
e co
nve
rsio
n is
on
e-w
ay;
they
can
no
t cy
cle
that
en
ergy
bac
k in
to it
s o
rigi
nal
fo
rm.
Liv
ing
org
an
ism
s ca
n u
se m
an
y
form
s o
f e
ne
rgy,
bu
t n
ot
he
at
To
un
der
stan
d w
hy
the
Ear
th m
ust
fu
nct
ion
as
an o
pen
sys
tem
w
ith
reg
ard
to
en
erg
y, t
wo
ad
dit
ion
al p
rin
cip
les
nee
d t
o b
e re
cog
niz
ed.
Th
e fi
rst
is t
hat
org
anis
ms
can
use
on
ly c
erta
in
form
s o
f en
erg
y. F
or
anim
als
to l
ive,
th
ey m
ust
hav
e en
erg
y sp
ecif
ical
ly a
s ch
emic
al-b
on
d e
ner
gy,
wh
ich
th
ey a
cqu
ire
fro
m
thei
r fo
od
s. P
lan
ts m
ust
hav
e en
erg
y as
lig
ht.
Nei
ther
an
imal
s n
or
pla
nts
(n
or
any
oth
er o
rgan
ism
s) c
an u
se h
eat
as a
so
urc
e o
f en
erg
y.
Le
arn
ing
Ou
tco
me
s R
ev
iew
58
.1An
eco
syst
em c
onsi
sts
of th
e liv
ing
and
nonl
ivin
g co
mpo
nent
s of
a p
arti
cula
r
plac
e. B
ioge
oche
mic
al c
ycle
s de
scri
be h
ow e
lem
ents
mov
e be
twee
n th
ese
com
pone
nts.
Car
bon,
nit
roge
n, a
nd p
hosp
horu
s cy
cle
in k
now
n w
ays,
as
does
wat
er, w
hich
is c
riti
cal t
o ec
osys
tem
s. H
uman
pop
ulat
ions
dis
rupt
thes
e
cycl
es w
ith
arti
fi ci
al fe
rtili
zati
on, d
efor
esta
tion
, div
ersi
on o
f wat
er, a
nd
burn
ing
of fo
ssil
fuel
s.
■
W
ou
ld f
ert
iliz
ati
on
wit
h a
nim
al m
an
ure
be
less
d
isru
pti
ve t
ha
n f
ert
iliz
ati
on
wit
h p
uri
fie
d c
he
mic
als
? W
hy
or
wh
y n
ot?
12
14
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
Tro
ph
ic L
evel
1
Pri
mary
pro
du
cers
Tro
ph
ic L
evel
2
Herb
ivo
res
Tro
ph
ic L
evel
3
Pri
mary
carn
ivo
res
Tro
ph
ic L
evel
4
Seco
nd
ary
carn
ivo
res
Detr
itiv
ore
s
Sun
Fig
ure
58
.8 T
rop
hic
le
ve
ls w
ith
in a
n e
cosy
ste
m.
Pri
mar
y p
rod
uce
rs s
uch
as
pla
nts
ob
tain
th
eir
ener
gy
dir
ectl
y fr
om
th
e S
un
,
pla
cin
g t
hem
in
tro
ph
ic l
evel
1.
An
imal
s th
at e
at p
lan
ts,
such
as
pla
nt-
eati
ng
in
sect
s, a
re h
erb
ivo
res
and
are
in
tro
ph
ic l
evel
2. A
nim
als
that
eat
the
her
biv
ore
s, s
uch
as
shre
ws,
are
pri
mar
y ca
rniv
ore
s an
d a
re i
n t
rop
hic
lev
el 3
. A
nim
als
that
eat
th
e p
rim
ary
carn
ivo
res,
su
ch a
s o
wls
, ar
e
seco
nd
ary
carn
ivo
res
in t
rop
hic
lev
el 4
. E
ach
tro
ph
ic l
evel
, al
tho
ug
h i
llu
stra
ted
her
e b
y a
par
ticu
lar
spec
ies,
co
nsi
sts
of
all
the
spec
ies
in t
he
eco
syst
em t
hat
fu
nct
ion
in
a s
imil
ar w
ay i
n t
erm
s o
f w
hat
th
ey e
at. T
he
org
anis
ms
in t
he
det
riti
vore
tro
ph
ic l
evel
co
nsu
me
dea
d o
rgan
ic
mat
ter
they
ob
tain
fro
m a
ll t
he
oth
er t
rop
hic
lev
els.
tro
ph
ic l
evel
s in
th
at t
hey
fee
d o
n t
he
rem
ain
s o
f al
read
y-d
ead
o
rgan
ism
s; d
etri
tus
is d
ead
org
anic
mat
ter.
A s
ub
cate
go
ry o
f d
etri
tivo
res
is t
he
deco
mp
ose
rs,
wh
ich
are
mo
stly
mic
rob
es
and
oth
er m
inu
te o
rgan
ism
s th
at l
ive
on
an
d b
reak
up
dea
d
org
anic
mat
ter.
Co
nce
pts
to
de
scri
be
tro
ph
ic le
ve
ls
Tro
ph
ic l
evel
s co
nsi
st o
f w
ho
le p
op
ula
tio
ns
of
org
anis
ms.
Fo
r ex
amp
le,
the
pri
mar
y-p
rod
uce
r tr
op
hic
lev
el c
on
sist
s o
f th
e w
ho
le p
op
ula
tio
ns
of
all
the
auto
tro
ph
ic s
pec
ies
in a
n e
cosy
s-te
m. E
colo
gis
ts h
ave
dev
elo
ped
a s
pec
ial s
et o
f te
rms
to r
efer
to
th
e p
rop
erti
es o
f p
op
ula
tio
ns
and
tro
ph
ic l
evel
s.
Th
e p
rod
uct
ivit
y o
f a
tro
ph
ic l
evel
is
the
rate
at
wh
ich
th
e o
rgan
ism
s in
th
e tr
op
hic
lev
el c
oll
ecti
vely
syn
thes
ize
new
o
rgan
ic m
atte
r (n
ew t
issu
e su
bst
ance
). P
rim
ary
pro
du
ctiv
ity
is
the
pro
du
ctiv
ity
of
the
pri
mar
y p
rod
uce
rs. A
n i
mp
ort
ant
com
-p
lexi
ty i
n a
nal
yzin
g t
he
pri
mar
y p
rod
uce
rs i
s th
at n
ot
on
ly d
o
they
syn
thes
ize
new
org
anic
mat
ter
by
ph
oto
syn
thes
is, b
ut
they
al
so b
reak
do
wn
so
me
of
the
org
anic
mat
ter
to r
elea
se e
ner
gy
by
mea
ns
of
aero
bic
cel
lula
r re
spir
atio
n (
see
chap
ter
7 ).
Th
e re
spir
atio
n o
f th
e p
rim
ary
pro
du
cers
, in
th
is c
on
text
, is
the
rate
at
wh
ich
th
ey b
reak
do
wn
org
anic
co
mp
ou
nd
s. G
ross
pri
mar
y p
rod
uct
ivit
y (G
PP
) is
sim
ply
th
e ra
w r
ate
at w
hic
h t
he
pri
-m
ary
pro
du
cers
syn
thes
ize
new
org
anic
mat
ter;
net
pri
mar
y p
rod
uct
ivit
y (N
PP
) is
th
e G
PP
min
us
the
resp
irat
ion
of
the
In
a w
ho
le e
cosy
stem
, man
y sp
ecie
s p
lay
sim
ilar
ro
les;
th
ere
is t
ypic
ally
no
t ju
st a
sin
gle
spec
ies
in e
ach
ro
le. F
or
exam
ple
, th
e an
imal
s th
at e
at p
lan
ts m
igh
t in
clu
de
no
t ju
st a
sin
gle
inse
ct s
pe-
cies
, bu
t p
erh
aps
30 s
pec
ies
of
inse
cts,
plu
s p
erh
aps
10 s
pec
ies
of
mam
mal
s. T
o o
rgan
ize
this
co
mp
lexi
ty,
eco
logi
sts
reco
gniz
e a
lim
ited
nu
mb
er o
f fe
edin
g, o
r tr
op
hic
, lev
els
(fig
ure
58.
8).
De
fin
itio
ns
of
tro
ph
ic le
ve
ls
Th
e fi
rst
tro
ph
ic l
evel
in
an
eco
syst
em,
call
ed t
he
pri
mar
y p
rod
uce
rs,
con
sist
s o
f al
l th
e au
totr
op
hs
in
the
syst
em.
Th
e o
ther
tr
op
hic
le
vels
co
nsi
st
of
the
het
ero
tro
ph
s—th
e co
nsu
mers
. All
th
e h
eter
otr
op
hs
that
fee
d d
irec
tly
on
th
e p
ri-
mar
y p
rod
uce
rs a
re p
lace
d t
og
eth
er i
n a
tro
ph
ic l
evel
cal
led
th
e h
erb
ivo
res.
In
tu
rn, t
he
het
ero
tro
ph
s th
at f
eed
on
th
e h
er-
biv
ore
s (e
atin
g t
hem
or
bei
ng
par
asit
ic o
n t
hem
) ar
e co
llec
-ti
vely
ter
med
pri
mar
y ca
rniv
ore
s, a
nd
th
ose
th
at f
eed
on
th
e p
rim
ary
carn
ivo
res
are
call
ed s
eco
nd
ary
carn
ivo
res.
A
dva
nce
d s
tud
ies
of
eco
syst
ems
nee
d t
o t
ake
into
acc
ou
nt
that
org
anis
ms
oft
en d
o n
ot
lin
e u
p i
n s
imp
le l
inea
r se
qu
ence
s in
ter
ms
of
wh
at t
hey
eat
; so
me
anim
als,
fo
r ex
amp
le, e
at b
oth
p
rim
ary
pro
du
cers
an
d o
ther
an
imal
s. A
lin
ear
seq
uen
ce o
f tr
op
hic
lev
els
is a
use
ful
org
aniz
ing
pri
nci
ple
fo
r m
any
pu
r-p
ose
s, h
ow
ever
.
An
ad
dit
ion
al c
on
sum
er l
evel
is
the
detr
itiv
ore
tro
ph
ic
leve
l. D
etri
tivo
res
dif
fer
fro
m th
e o
rgan
ism
s in
th
e o
ther
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
21
5w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
17%
gro
wth
33%
cellu
lar
respiration
50%
feces
Fig
ure
58
.9 T
he
fa
te o
f in
ge
ste
d c
he
mic
al-
bo
nd
en
erg
y:
Wh
y a
ll t
he
en
erg
y i
ng
est
ed
by
a h
ete
rotr
op
h i
s n
ot
av
ail
ab
le t
o t
he
ne
xt
tro
ph
ic l
ev
el.
A
het
ero
tro
ph
su
ch a
s th
is
her
biv
oro
us
inse
ct a
ssim
ilat
es o
nly
a f
ract
ion
of
the
chem
ical
-bo
nd
ener
gy
it i
ng
ests
. In
th
is e
xam
ple
, 50
% i
s n
ot
assi
mil
ated
an
d i
s
elim
inat
ed i
n f
eces
; th
is e
lim
inat
ed c
hem
ical
-bo
nd
en
erg
y ca
nn
ot
be
use
d b
y th
e p
rim
ary
carn
ivo
res.
A t
hir
d (
33%
) o
f th
e in
ges
ted
ener
gy
is u
sed
to
fu
el c
ellu
lar
resp
irat
ion
an
d t
hu
s is
co
nve
rted
to
hea
t, w
hic
h c
ann
ot
be
use
d b
y th
e p
rim
ary
carn
ivo
res.
On
ly 1
7% o
f
the
ing
este
d e
ner
gy
is c
on
vert
ed i
nto
in
sect
bio
mas
s th
rou
gh
gro
wth
an
d c
an s
erve
as
foo
d f
or
the
nex
t tr
op
hic
lev
el,
bu
t n
ot
even
that
per
cen
tag
e is
cer
tain
to
be
use
d i
n t
hat
way
bec
ause
so
me
of
the
inse
cts
die
bef
ore
th
ey a
re e
aten
.
pri
mar
y p
rod
uce
rs.
Th
e N
PP
rep
rese
nts
th
e o
rgan
ic m
atte
r av
aila
ble
fo
r h
erb
ivo
res
to u
se a
s fo
od
.
Th
e p
rod
uct
ivit
y o
f a
het
ero
tro
ph
tro
ph
ic l
evel
is
term
ed
seco
nd
ary
pro
du
ctiv
ity.
Fo
r in
stan
ce,
the
rate
th
at n
ew o
r-g
anic
mat
ter
is m
ade
by
mea
ns
of
ind
ivid
ual
gro
wth
an
d r
epro
-d
uct
ion
in
all
th
e h
erb
ivo
res
in a
n e
cosy
stem
is
the
seco
nd
ary
pro
du
ctiv
ity
of
the
her
biv
ore
tro
ph
ic l
evel
. E
ach
het
ero
tro
ph
tr
op
hic
lev
el h
as i
ts o
wn
sec
on
dar
y p
rod
uct
ivit
y.
Ho
w t
rop
hic
lev
els
pro
cess
en
erg
y
Th
e fr
acti
on
of
inco
min
g s
ola
r ra
dia
nt
ener
gy
that
th
e p
ri-
mar
y p
rod
uce
rs c
aptu
re i
s sm
all.
Ave
rag
ed o
ver
the
cou
rse
of
a ye
ar,
som
eth
ing
aro
un
d 1
% o
f th
e so
lar
ener
gy
imp
ing
ing
o
n f
ore
sts
or
oce
ans
is c
aptu
red
. In
vest
igat
ors
so
met
imes
ob
-se
rve
far
low
er l
evel
s, b
ut
also
see
per
cen
tag
es a
s h
igh
as
5%
u
nd
er s
om
e co
nd
itio
ns.
Th
e so
lar
ener
gy
no
t ca
ptu
red
as
chem
ical
-bo
nd
en
erg
y th
rou
gh
ph
oto
syn
thes
is is
imm
edia
tely
co
nve
rted
to
hea
t.
Th
e p
rim
ary
pro
du
cers
, as
no
ted
bef
ore
, car
ry o
ut
resp
i-ra
tio
n i
n w
hic
h t
hey
bre
ak d
ow
n s
om
e o
f th
e o
rgan
ic c
om
-p
ou
nd
s in
th
eir
bo
die
s to
rel
ease
ch
emic
al-b
on
d e
ner
gy.
Th
ey
use
a p
ort
ion
of
this
ch
emic
al-b
on
d e
ner
gy
to m
ake
AT
P, w
hic
h
they
in
tu
rn u
se t
o p
ow
er v
ario
us
ener
gy-
req
uir
ing
pro
cess
es.
Ult
imat
ely,
th
e ch
emic
al-b
on
d e
ner
gy
they
rel
ease
by
resp
ira-
tio
n t
urn
s to
hea
t.
Rem
emb
er t
hat
org
anis
ms
can
no
t u
se h
eat
to s
tay
aliv
e.
As
a re
sult
, w
hen
ever
en
erg
y ch
ang
es f
orm
to
bec
om
e h
eat,
it
lose
s m
uch
or
all o
f it
s u
sefu
lnes
s fo
r o
rgan
ism
s as
a f
uel
so
urc
e.
Wh
at w
e h
ave
seen
so
far
is
that
ab
ou
t 9
9%
of
the
sola
r en
erg
y im
pin
gin
g o
n a
n e
cosy
stem
tu
rns
to h
eat
bec
ause
it
fail
s to
be
use
d b
y p
ho
tosy
nth
esis
. Th
en s
om
e o
f th
e en
erg
y ca
ptu
red
by
ph
oto
syn
thes
is a
lso
bec
om
es h
eat
bec
ause
of
resp
irat
ion
by
the
pri
mar
y p
rod
uce
rs. A
ll t
he
het
ero
tro
ph
s in
an
eco
syst
em m
ust
li
ve o
n t
he
chem
ical
-bo
nd
en
erg
y th
at i
s le
ft.
An
ex
am
ple
of
en
erg
y lo
ss b
etw
ee
n t
rop
hic
lev
els
As
chem
ical
-bo
nd
en
ergy
is p
asse
d fr
om
on
e h
eter
otr
op
h t
rop
hic
le
vel
to t
he
nex
t, a
gre
at d
eal
of
the
ener
gy i
s d
iver
ted
all
alo
ng
th
e w
ay. T
his
pri
nci
ple
has
dra
mat
ic c
on
seq
uen
ces.
It
mea
ns
that
, o
ver
any
par
ticu
lar
per
iod
of
tim
e, t
he
amo
un
t o
f ch
emic
al-b
on
d
ener
gy a
vail
able
to
pri
mar
y ca
rniv
ore
s is
far
les
s th
an t
hat
ava
il-
able
to
her
biv
ore
s, a
nd
th
e am
ou
nt
avai
lab
le t
o s
eco
nd
ary
carn
i-vo
res
is f
ar les
s th
an t
hat
ava
ilab
le t
o p
rim
ary
carn
ivo
res.
W
hy
do
es t
he
amo
un
t o
f ch
emic
al-b
on
d e
ner
gy
dec
reas
e as
en
erg
y is
pas
sed
fro
m o
ne
tro
ph
ic le
vel t
o t
he
nex
t? C
on
sid
er
the
use
of
ener
gy
by
the
her
biv
ore
tro
ph
ic l
evel
as
an e
xam
ple
(f
igu
re 5
8.9
). A
fter
an
her
biv
ore
su
ch a
s a
leaf
-eat
ing
in
sect
in
-g
ests
so
me
foo
d, it
pro
du
ces
fece
s. T
he
chem
ical
-bo
nd
en
erg
y in
th
e co
mp
ou
nd
s in
th
e fe
ces
is n
ot
pas
sed
alo
ng
to
th
e p
ri-
mar
y ca
rniv
ore
tro
ph
ic lev
el. T
he
chem
ical
-bo
nd
en
erg
y o
f th
e fo
od
th
at is
ass
imil
ated
by
the
her
biv
ore
is u
sed
fo
r a
nu
mb
er o
f fu
nct
ion
s. P
art
of
the
assi
mil
ated
en
erg
y is
lib
erat
ed b
y ce
llu
lar
resp
irat
ion
to
be
use
d f
or
tiss
ue
rep
air,
bo
dy
mo
vem
ents
, an
d
oth
er s
uch
fu
nct
ion
s. T
he
ener
gy
use
d i
n t
hes
e w
ays
turn
s to
h
eat
and
is
no
t p
asse
d a
lon
g t
o t
he
carn
ivo
re t
rop
hic
lev
el.
So
me
chem
ical
-bo
nd
en
erg
y is
bu
ilt
into
th
e ti
ssu
es o
f th
e h
er-
biv
ore
an
d c
an s
erve
as
foo
d f
or
a ca
rniv
ore
. H
ow
ever
, so
me
her
biv
ore
in
div
idu
als
die
of
dis
ease
or
acci
den
t ra
ther
th
an b
e-in
g e
aten
by
pre
dat
ors
.
In
th
e en
d,
of
cou
rse,
so
me
of
the
init
ial
chem
ical
-bo
nd
en
erg
y ac
qu
ired
fro
m t
he
leaf
is
bu
ilt
into
th
e ti
ssu
es o
f h
erb
i-vo
re i
nd
ivid
ual
s th
at a
re e
aten
by
pri
mar
y ca
rniv
ore
s. M
uch
of
the
init
ial c
hem
ical
-bo
nd
en
erg
y, h
ow
ever
, is
div
erte
d in
to h
eat,
fe
ces,
an
d t
he
bo
die
s o
f h
erb
ivo
re in
div
idu
als
that
car
niv
ore
s d
o
no
t g
et t
o e
at. T
he
sam
e sc
enar
io i
s re
pea
ted
at
each
ste
p i
n a
se
ries
of
tro
ph
ic l
evel
s (f
igu
re 5
8.1
0).
Eco
log
ists
fig
ure
as
a ru
le o
f th
um
b t
hat
th
e am
ou
nt
of
chem
ical
-bo
nd
en
erg
y av
aila
ble
to
a t
rop
hic
lev
el o
ver
tim
e is
ab
ou
t 1
0%
of th
at a
vail
able
to
th
e p
rece
din
g le
vel o
ver
the
sam
e p
erio
d o
f ti
me.
In
so
me
inst
ance
s th
e p
erce
nta
ge
is h
igh
er, e
ven
as
hig
h a
s 3
0%
.
He
at
as
the
fin
al e
ne
rgy
pro
du
ct
Ess
enti
ally
all
of
the
chem
ical
-bo
nd
en
erg
y ca
ptu
red
by
ph
oto
-sy
nth
esis
in
an
ec
osy
stem
ev
entu
ally
b
eco
mes
h
eat
as
the
chem
ical
-bo
nd
en
erg
y is
use
d b
y va
rio
us
tro
ph
ic l
evel
s. T
o s
ee
this
im
po
rtan
t p
oin
t, r
eco
gn
ize
that
wh
en t
he
det
riti
vore
s in
th
e ec
osy
stem
met
abo
lize
all
th
e d
ead
bo
die
s, f
eces
, an
d o
ther
m
ater
ials
mad
e av
aila
ble
to
th
em,
they
pro
du
ce h
eat
just
lik
e th
e o
ther
tro
ph
ic l
evel
s d
o.
Pro
du
ctiv
e e
cosy
ste
ms
Eco
syst
ems
vary
co
nsi
der
ably
in t
hei
r N
PP.
Wet
lan
ds
and
tro
p-
ical
rai
n f
ore
sts
are
exam
ple
s o
f p
arti
cula
rly
pro
du
ctiv
e ec
osy
s-te
ms
(fig
ure
58
.11
) ; i
n t
hem
, th
e N
PP,
mea
sure
d a
s d
ry w
eig
ht
of
new
org
anic
mat
ter
pro
du
ced
, is
oft
en a
rou
nd
20
00
g/m
2/
year
. B
y co
ntr
ast,
th
e co
rres
po
nd
ing
fig
ure
s fo
r so
me
oth
er
typ
es o
f ec
osy
stem
s ar
e 1
20
0 t
o 1
30
0 f
or
tem
per
ate
fore
sts,
90
0
for
sava
nn
a, a
nd
90
fo
r d
eser
ts. (
Th
ese
gen
eral
eco
syst
em t
ypes
, te
rmed
bio
mes
, ar
e d
escr
ibed
in
th
e fo
llo
win
g c
hap
ter.
)
12
16
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
Pri
mary
pro
du
cers
Detr
itiv
ore
s
Herb
ivo
res
Pri
mary
carn
ivo
res
So
lar
en
erg
y
Seco
nd
ary
carn
ivo
res
Chem
ical-bond
energ
y in d
ead
bodie
s,
feces,
and o
ther
non-
livin
g o
rganic
pro
ducts
usefu
lonly
to
detr
itiv
ore
s.
Heat
1%
Re
sp
iration
Feces a
nd d
eath
Respira
tio
n
Re
spiration
Respir
ation
Fece
sand
death
Death
Resp
irat
ion
99%
sola
rener
gyab
sorb
ed as heat
Fecesanddeath
Fec
esan
ddeath
Alg
al beds a
nd r
eefs
Tro
pic
al ra
in f
ore
st
Wetlands
Tro
pic
al seasonal fo
rest
Estu
aries
Tem
pera
te e
verg
reen f
ore
st
Tem
pera
te d
ecid
uous f
ore
st
Savanna
Bore
al fo
rest
Woodla
nd a
nd s
hru
bla
nd
Cultiv
ate
d land
Tem
pera
te g
rassla
nd
Continenta
l shelf
Lake a
nd s
tream
Tundra
and a
lpin
e
Open o
cean
Desert
and s
em
idesert
Extr
em
e d
esert
NP
P p
er
unit a
rea (
g d
ry m
att
er/
m2/y
r)
World N
PP
(10
12 k
g d
ry m
att
er/
m2/y
r)
0
500
1000
1500
2000
2500
0
20
30
40
50
10
Fig
ure
58
.10
Th
e #
ow
of
en
erg
y t
hro
ug
h a
n e
cosy
ste
m.
Blu
e ar
row
s re
pre
sen
t th
e *
ow
of
ener
gy
that
en
ters
th
e ec
osy
stem
as
lig
ht
and
is
then
pas
sed
alo
ng
as
chem
ical
-bo
nd
en
erg
y to
su
cces
sive
tro
ph
ic l
evel
s. A
t ea
ch s
tep
en
erg
y
is d
iver
ted
, m
ean
ing
th
at t
he
chem
ical
-bo
nd
en
erg
y av
aila
ble
to
each
tro
ph
ic l
evel
is
less
th
an t
hat
avai
lab
le t
o t
he
pre
ced
ing
tro
ph
ic
leve
l. R
ed a
rro
ws
rep
rese
nt
div
ersi
on
s o
f en
erg
y in
to h
eat.
Tan
arro
ws
rep
rese
nt
div
ersi
on
s o
f
ener
gy
into
fec
es a
nd
oth
er o
rgan
ic
mat
eria
ls u
sefu
l o
nly
to
th
e
det
riti
vore
s. D
etri
tivo
res
may
be
eate
n b
y ca
rniv
ore
s, s
o s
om
e o
f th
e
chem
ical
-bo
nd
en
erg
y re
turn
s to
hig
her
tro
ph
ic l
evel
s.
Fig
ure
58
.11
Eco
syst
em
pro
du
cti
vit
y p
er
ye
ar.
Th
e
& rs
t co
lum
n o
f d
ata
sho
ws
the
aver
age
net
pri
mar
y p
rod
uct
ivit
y
(NP
P)
per
sq
uar
e m
eter
per
yea
r.
Th
e se
con
d c
olu
mn
of
dat
a
fact
ors
in
th
e ar
ea c
ove
red
by
the
eco
syst
em t
yp
e; i
t is
th
e p
rod
uct
of
the
pro
du
ctiv
ity
per
sq
uar
e
met
er p
er y
ear
tim
es t
he
nu
mb
er
of
squ
are
met
ers
occ
up
ied
by
the
eco
syst
em t
yp
e w
orl
dw
ide.
No
te
that
an
eco
syst
em t
yp
e th
at i
s
very
pro
du
ctiv
e o
n a
sq
uar
e-
met
er b
asis
may
no
t co
ntr
ibu
te
mu
ch t
o g
lob
al p
rod
uct
ivit
y if
it
is a
n u
nco
mm
on
ty
pe,
su
ch a
s
wet
lan
ds.
On
th
e o
ther
han
d, a
very
wid
esp
read
eco
syst
em t
yp
e,
such
as
the
op
en o
cean
, ca
n
con
trib
ute
gre
atly
to
glo
bal
pro
du
ctiv
ity
even
if
its
pro
du
ctiv
ity
per
sq
uar
e m
eter
is l
ow
.So
urce
: Dat
a in
: Beg
on, M
., J.
L. H
arpe
r, an
d C.
R. T
owns
end,
Eco
logy
3/e
, Bla
ckw
ell S
cien
ce, 1
996,
pag
e 71
5. O
rigi
nal s
ourc
e: W
hitt
aker
, R. H
. Com
mun
ities
and
Eco
syst
ems,
2/e
, Mac
mill
an,
Lond
on, 1
975.
Th
e n
um
be
r o
f tr
op
hic
lev
els
is
lim
ite
d b
y e
ne
rgy
av
ail
ab
ilit
y
Th
e ra
te a
t w
hic
h c
hem
ical
-bo
nd
en
ergy
is m
ade
avai
lab
le t
o
org
anis
ms
in d
iffe
ren
t tr
op
hic
lev
els
dec
reas
es e
xpo
nen
tial
ly a
s en
ergy
mak
es it
s w
ay f
rom
pri
mar
y p
rod
uce
rs t
o h
erb
ivo
res
and
then
to
var
iou
s le
vels
of
carn
ivo
res.
To
en
visi
on
th
is c
riti
cal
po
int,
ass
um
e fo
r si
mp
lici
ty t
hat
th
e p
rim
ary
pro
du
cers
in
an
ec
osy
stem
gai
n 1
000 u
nit
s o
f ch
emic
al-b
on
d e
ner
gy
ove
r a
pe-
rio
d o
f ti
me.
If
the
ener
gy
inp
ut
to e
ach
tro
ph
ic l
evel
is
10%
of
the
inp
ut
to t
he
pre
ced
ing l
evel
, th
en t
he
inp
ut
of
chem
ical
-b
on
d e
ner
gy
to t
he
her
biv
ore
tro
ph
ic l
evel
is
100 u
nit
s, t
o t
he
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
21
7w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
Pri
mary
pro
ducers
(alg
ae a
nd c
yanobacte
ria)
Herb
ivore
s(a
nim
al pla
nkto
n)
Sm
elt
Hum
an
Tro
ut
1.2
calo
ries
6 c
alo
ries30 c
alo
ries
150 c
alo
ries
1000 c
alo
ries
Fig
ure
58
.12
Flo
w o
f e
ne
rgy
th
rou
gh
th
e t
rop
hic
le
ve
ls
of
Ca
yu
ga
La
ke
. A
uto
tro
ph
ic p
lan
kto
n (
alg
ae a
nd
cya
no
bac
teri
a)
& x
the
ener
gy
of
the
Su
n,
the
her
biv
ore
s (a
nim
al p
lan
kto
n)
feed
on
them
, an
d b
oth
are
co
nsu
med
by
smel
t. T
he
smel
t ar
e ea
ten
by
tro
ut.
Th
e am
ou
nt
of
& sh
* e
sh p
rod
uce
d p
er u
nit
tim
e fo
r h
um
an
con
sum
pti
on
is
at l
east
& v
e ti
mes
gre
ater
if
peo
ple
eat
sm
elt
rath
er
than
tro
ut,
bu
t p
eop
le t
yp
ical
ly p
refe
r to
eat
tro
ut.
Inq
uir
y q
ue
stio
n
?
Wh
y d
oe
s it
ta
ke
so
ma
ny
ca
lori
es
of
alg
ae
to
su
pp
ort
so
fe
w
calo
rie
s o
f h
um
an
s?
In
a p
yram
id o
f b
iom
ass,
th
e w
idth
s o
f th
e b
oxe
s ar
e d
raw
n t
o b
e p
rop
ort
ion
al t
o s
tan
din
g c
rop
bio
mas
s. U
sual
ly,
tro
ph
ic l
evel
s th
at h
ave
rela
tive
ly l
ow
pro
du
ctiv
ity
also
hav
e re
lati
vely
lit
tle
bio
mas
s p
rese
nt
at a
giv
en t
ime.
Th
us,
pyr
amid
s o
f b
iom
ass
are
usu
ally
up
rig
ht,
mea
nin
g e
ach
bo
x is
nar
row
er
than
th
e o
ne
bel
ow
it
(fig
ure
58
.13
b).
An
up
rig
ht
pyr
amid
of
bio
mas
s is
no
t m
and
ated
by
fun
dam
enta
l an
d i
nvi
ola
ble
ru
les
like
an
up
rig
ht
pyr
amid
of
pro
du
ctiv
ity
is,
ho
wev
er.
In s
om
e ec
osy
stem
s, t
he
pyr
amid
of
bio
mas
s is
in
vert
ed
, m
ean
ing
th
at
at l
east
on
e tr
op
hic
lev
el h
as g
reat
er b
iom
ass
than
th
e o
ne
be-
low
it
(fig
ure
58
.13
c).
H
ow
is
it p
oss
ible
fo
r th
e p
yram
id o
f b
iom
ass
to b
e in
-ve
rted
? C
on
sid
er a
co
mm
on
so
rt o
f aq
uat
ic s
yste
m in
wh
ich
th
e p
rim
ary
pro
du
cers
are
sin
gle
-cel
led
alg
ae (
ph
yto
pla
nkt
on
), a
nd
th
e h
erb
ivo
res
are
rice
gra
in-s
ized
an
imal
s (s
uch
as
cop
epo
ds)
th
at f
eed
dir
ectl
y o
n t
he
alg
al c
ells
. In
su
ch a
sys
tem
, th
e tu
rn-
ove
r o
f th
e al
gal
cel
ls i
s o
ften
ver
y ra
pid
: T
he
cell
s m
ult
iply
ra
pid
ly, b
ut
the
anim
als
con
sum
e th
em e
qu
ally
rap
idly
. In
th
ese
circ
um
stan
ces,
th
e al
gal
cel
ls n
ever
dev
elo
p a
lar
ge
po
pu
lati
on
si
ze
or
larg
e b
iom
ass.
N
on
eth
eles
s,
bec
ause
th
e al
gal
ce
lls
are
very
pro
du
ctiv
e, t
he
eco
syst
em c
an s
up
po
rt a
su
bst
anti
al
pri
mar
y ca
rniv
ore
s, 1
0 u
nit
s, a
nd
to
th
e se
con
dar
y ca
rniv
ore
s,
1 u
nit
ove
r th
e sa
me
per
iod
of
tim
e.
Lim
its
on
to
p c
arn
ivo
res
Th
e ex
po
nen
tial
dec
lin
e o
f ch
emic
al-b
on
d e
ner
gy
in a
tro
ph
ic
chai
n l
imit
s th
e le
ngth
s o
f tr
op
hic
ch
ain
s an
d t
he
nu
mb
ers
of
top
car
niv
ore
s an
eco
syst
em c
an s
up
po
rt.
Acc
ord
ing t
o o
ur
mo
del
cal
cula
tio
ns,
if
an e
cosy
stem
in
clu
des
sec
on
dar
y ca
rni-
vore
s, o
nly
ab
ou
t o
ne-
tho
usa
nd
th o
f th
e en
ergy
cap
ture
d b
y p
ho
tosy
nth
esis
pas
ses
all
the
way
th
rou
gh
th
e se
ries
of
tro
ph
ic
leve
ls t
o r
each
th
ese
anim
als
as u
sab
le c
hem
ical
-bo
nd
en
ergy.
T
erti
ary
carn
ivo
res
wo
uld
rec
eive
on
ly o
ne
ten
-th
ou
san
dth
. Th
is
hel
ps
exp
lain
wh
y n
o p
red
ato
rs s
ub
sist
so
lely
on
eag
les
or
lio
ns.
T
he
dec
lin
e o
f av
aila
ble
ch
emic
al-b
on
d e
ner
gy
also
hel
ps
exp
lain
wh
y th
e n
um
ber
s o
f in
div
idu
al t
op
-lev
el c
arn
ivo
res
in a
n
eco
syst
em t
end
to
be
low
. Th
e w
ho
le t
rop
hic
lev
el o
f to
p c
arn
i-vo
res
rece
ives
rel
ativ
ely
litt
le e
ner
gy,
an
d y
et s
uch
car
niv
ore
s te
nd
to
be
big
: T
hey
hav
e re
lati
vely
lar
ge
ind
ivid
ual
bo
dy
size
s an
d g
reat
in
div
idu
al e
ner
gy
nee
ds.
Bec
ause
of
thes
e tw
o f
acto
rs,
the
po
pu
lati
on
nu
mb
ers
of
top
pre
dat
ors
ten
d t
o b
e sm
all.
T
he
lon
ges
t tr
op
hic
ch
ain
s p
rob
ably
occ
ur
in t
he
oce
ans.
S
om
e tu
nas
an
d o
ther
to
p-l
evel
oce
an p
red
ato
rs p
rob
ably
fu
nc-
tio
n a
s th
ird
- an
d f
ou
rth
-lev
el c
arn
ivo
res
at t
imes
. T
he
chal
-le
ng
e o
f ex
pla
inin
g s
uch
lo
ng
tro
ph
ic c
hai
ns
is o
bvi
ou
s, b
ut
the
solu
tio
ns
are
no
t w
ell
un
der
sto
od
pre
sen
tly.
Hu
ma
ns
as
con
sum
ers
: A c
ase
stu
dy
Th
e fl
ow
o
f en
ergy
in
C
ayu
ga
Lak
e in
u
pst
ate
New
Y
ork
(f
igure
58.
12)
hel
ps
illu
stra
te h
ow
th
e en
erge
tics
of
troph
ic l
evel
s ca
n a
ffec
t th
e h
um
an food s
upply
. Res
earc
her
s ca
lcula
ted fro
m t
he
actu
al p
roper
ties
of
this
eco
syst
em t
hat
about
150
of
each
100
0
calo
ries
of
chem
ical
-bon
d e
ner
gy c
aptu
red b
y pri
mar
y pro
duce
rs
in t
he
lake
wer
e tr
ansf
erre
d in
to t
he
bodie
s of h
erbiv
ore
s. O
f th
ese
calo
ries
, about
30 w
ere
tran
sfer
red i
nto
th
e bodie
s of
smel
t, s
mal
l fi
sh t
hat
wer
e th
e pri
nci
pal
pri
mar
y ca
rniv
ore
s in
th
e sy
stem
.
If h
um
ans
ate
the
smel
t, t
hey
gai
ned
ab
ou
t 6
of
the
10
00
ca
lori
es t
hat
ori
gin
ally
en
tere
d t
he
syst
em. I
f tr
ou
t at
e th
e sm
elt
and
h
um
ans
ate
the
tro
ut,
th
e h
um
ans
gai
ned
o
nly
ab
ou
t 1
.2 c
alo
ries
. Fo
r h
um
an p
op
ula
tio
ns
in g
ener
al, m
ore
en
erg
y is
av
aila
ble
if
pla
nts
or
oth
er p
rim
ary
pro
du
cers
are
eat
en t
han
if
anim
als
are
eate
n—
and
mo
re e
ner
gy
is a
vail
able
if
her
biv
ore
s ra
ther
th
an c
arn
ivo
res
are
con
sum
ed.
Eco
log
ica
l py
ram
ids
illu
stra
te
the
re
lati
on
ship
of
tro
ph
ic le
ve
ls
Imag
ine
that
th
e tr
op
hic
lev
els
of
an e
cosy
stem
are
rep
re-
sen
ted
as
bo
xes
stac
ked
on
to
p o
f ea
ch o
ther
. Im
agin
e al
so t
hat
th
e w
idth
of
each
bo
x is
pro
po
rtio
nal
to
th
e p
rod
uct
ivit
y o
f th
e tr
op
hic
lev
el i
t re
pre
sen
ts. T
he
stac
k o
f b
oxe
s w
ill
alw
ays
hav
e th
e sh
ape
of
a p
yram
id;
each
bo
x is
nar
row
er t
han
th
e o
ne
un
der
it
bec
ause
of
the
invi
ola
ble
ru
les
of
ener
gy
flo
w. A
d
iag
ram
of
this
so
rt is
cal
led
a p
yram
id o
f en
erg
y fl
ow
or
pyr
a-m
id o
f p
rod
uct
ivit
y (f
igu
re 5
8.1
3a)
. It
is a
n e
xam
ple
of
an e
co-
log
ical
pyr
amid
.
Th
ere
are
seve
ral
typ
es o
f ec
olo
gic
al p
yram
ids.
Pyr
amid
d
iag
ram
s ca
n b
e u
sed
to
rep
rese
nt
stan
din
g c
rop
bio
mas
s o
r n
um
ber
s o
f in
div
idu
als,
as
wel
l as
pro
du
ctiv
ity.
12
18
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
b.
Photo
synth
etic p
lankto
n
(36,3
80 k
cal/m
2/y
ear)
4,0
00,0
00,0
00
111
Carn
ivore
Herb
ivore
First-
level carn
ivore
(48 k
cal/m
2/y
ear)
Herb
ivore
(596 k
cal/m
2/y
ear)
a.
Pyra
mid
of
En
erg
y F
low
(P
rod
ucti
vit
y)
Pyra
mid
of
Bio
mass
Invert
ed
Pyra
mid
of
Bio
mass
Pyra
mid
of
Nu
mb
ers
Photo
synth
etic p
lankto
n
(807 g
/m2)
Herb
ivore
(37 g
/m2)
First-
level carn
ivore
(11 g
/m2)
Phyto
pla
nkto
n
(4 g
/m2)
Herb
ivoro
us z
oopla
nkto
n a
nd
bott
om
fauna (
21 g
/m2)
c.
d.
Photo
synth
etic
pla
nkto
n
bio
mas
s o
f th
e an
imal
s, a
bio
mas
s la
rger
th
an t
hat
eve
r o
bse
rved
in
th
e al
gal
po
pu
lati
on
.
In a
pyr
amid
of
nu
mb
ers,
th
e w
idth
s o
f th
e b
oxe
s ar
e p
ro-
po
rtio
nal
to
th
e n
um
ber
s o
f in
div
idu
als
pre
sen
t in
th
e va
rio
us
tro
ph
ic l
evel
s (f
igu
re 5
8.1
3d)
. S
uch
pyr
amid
s ar
e u
sual
ly,
bu
t n
ot
alw
ays,
up
rig
ht.
Le
arn
ing
Ou
tco
me
s R
ev
iew
58
.2Tr
ophi
c le
vels
in a
n ec
osys
tem
incl
ude
prim
ary
prod
ucer
s, h
erbi
vore
s,
prim
ary
carn
ivor
es, a
nd s
econ
dary
car
nivo
res.
Det
riti
vore
s co
nsum
e de
ad
or w
aste
mat
ter f
rom
all
leve
ls. A
s en
ergy
pas
ses
from
one
leve
l to
anot
her,
som
e is
inev
itab
ly lo
st a
s he
at, w
hich
can
not b
e re
clai
med
. Pho
tosy
nthe
tic
prim
ary
prod
ucer
s ca
ptur
e ab
out 1
% o
f sol
ar e
nerg
y as
che
mic
al-b
ond
ener
gy. A
s th
is e
nerg
y is
pas
sed
thro
ugh
the
othe
r tro
phic
leve
ls, s
ome
is
dive
rted
at e
ach
step
into
hea
t, fe
ces,
and
dea
d m
atte
r; o
nly
abou
t 10%
is
avai
labl
e to
the
next
leve
l.
■
D
esc
rib
e th
e d
iffe
ren
t w
ays
th
at
ma
tte
r, s
uch
as
carb
on
a
tom
s, a
nd
en
erg
y m
ove
th
rou
gh
eco
syst
em
s?
Le
arn
ing
Ou
tco
me
s
Exp
lain
th
e m
ea
nin
g o
f tr
op
hic
ca
sca
de
.1.
Dis
tin
gu
ish
be
twe
en
to
p-d
ow
n a
nd
bo
tto
m-u
p e
ffe
cts.
2.
58
.3
Tro
ph
ic-L
evel
Inte
ract
ion
s
Fig
ure
58
.13
Eco
log
ica
l
py
ram
ids.
In
an
eco
log
ical
py
ram
id, su
cces
sive
tro
ph
ic
leve
ls i
n a
n e
cosy
stem
are
rep
rese
nte
d a
s st
acke
d b
oxe
s,
and
th
e w
idth
s o
f th
e b
oxe
s
rep
rese
nt
the
mag
nit
ud
e o
f an
eco
log
ical
pro
per
ty i
n t
he
vari
ou
s tr
op
hic
lev
els.
Eco
log
ical
py
ram
ids
can
rep
rese
nt
seve
ral
dif
fere
nt
pro
per
ties
. a.
Py
ram
id o
f
ener
gy
" o
w (
pro
du
ctiv
ity)
.
b.
Py
ram
id o
f b
iom
ass
of
the
ord
inar
y ty
pe.
c.
Inve
rted
py
ram
id o
f b
iom
ass.
d.
Py
ram
id o
f n
um
ber
s.
Inq
uir
y q
ue
stio
n
?
Ho
w c
an
th
e e
xis
ten
ce
of
inv
ert
ed
py
ram
ids
of
bio
ma
ss b
e e
xp
lain
ed
?
Th
e ex
iste
nce
of
foo
d c
hai
ns
crea
tes
the
po
ssib
ilit
y th
at s
pec
ies
in a
ny
on
e tr
op
hic
lev
el m
ay h
ave
effe
cts
on
mo
re t
han
on
e tr
op
hic
leve
l. P
rim
ary
carn
ivo
res,
fo
r ex
amp
le, m
ay h
ave
effe
cts
no
t o
nly
on
th
e an
imal
s th
ey e
at,
bu
t al
so,
ind
irec
tly,
on
th
e p
lan
ts o
r al
gae
eat
en b
y th
eir
pre
y. C
on
vers
ely,
in
crea
ses
in p
ri-
mar
y p
rod
uct
ivit
y m
ay p
rovi
de
mo
re f
oo
d n
ot
just
to
her
bi-
vore
s, b
ut
also
, in
dir
ectl
y, t
o c
arn
ivo
res.
T
he
pro
cess
by
wh
ich
eff
ects
exe
rted
at
an u
pp
er t
rop
hic
le
vel f
low
do
wn
to
infl
uen
ce t
wo
or
mo
re lo
wer
leve
ls is
ter
med
a
tro
ph
ic c
asca
de. T
he
effe
cts
them
selv
es a
re c
alle
d t
op
-dow
n
eff
ect
s. W
hen
an
eff
ect
flo
ws
up
th
rou
gh
a t
rop
hic
ch
ain
, su
ch
as f
rom
pri
mar
y p
rod
uce
rs t
o h
igh
er t
rop
hic
lev
els,
it
is t
erm
ed
a b
ott
om
-up
eff
ect
.
Top
-do
wn
e!
ect
s o
ccu
r w
he
n c
ha
ng
es
in t
he
top
tro
ph
ic le
ve
l a!
ect
pri
ma
ry p
rod
uce
rs
Th
e ex
iste
nce
of
top
-do
wn
eff
ects
has
bee
n c
on
firm
ed b
y co
ntr
oll
ed e
xper
imen
ts i
n s
om
e ty
pes
of
eco
syst
ems,
par
ticu
-la
rly
fres
hw
ater
on
es. F
or
exam
ple
, in
on
e st
ud
y, s
ecti
on
s o
f a
stre
am w
ere
encl
ose
d w
ith
a m
esh
th
at p
reve
nte
d f
ish
fro
m
ente
rin
g.
Bro
wn
tr
ou
t—p
red
ato
rs
on
in
vert
ebra
tes—
wer
e ad
ded
to
so
me
encl
osu
res
bu
t n
ot
oth
ers.
Aft
er 1
0 d
ays,
th
e n
um
ber
s o
f in
vert
ebra
tes
in t
he
encl
osu
res
wit
h t
rou
t w
ere
on
ly t
wo
-th
ird
s as
gre
at a
s th
e n
um
ber
s in
th
e n
o-f
ish
en
clo
-su
res
(fig
ure
58
.14
). I
n t
urn
, th
e b
iom
ass
of
alg
ae,
wh
ich
th
e in
vert
ebra
tes
ate,
was
fiv
e ti
mes
gre
ater
in
th
e tr
ou
t en
clo
-su
res
than
th
e n
o-f
ish
on
es.
T
he
log
ic o
f th
e tr
op
hic
cas
cad
e ju
st d
escr
ibed
lea
ds
to
the
exp
ecta
tio
n
that
if
se
con
dar
y ca
rniv
ore
s ar
e ad
ded
to
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
21
9w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
No f
ish
Tro
ut
No f
ish
Tro
ut
Invertebrates (number/m2)
Algae (μg chlorophyll a/cm2)
5000
4000
3000
2000
1000 0
2.0
1.5
1.0
0.5 0
Herb
ivoro
us
insects
Alg
ae
Carn
ivoro
us
dam
selfly
nym
phs
Herb
ivoro
us
insects
Alg
ae
Carn
ivoro
us
dam
selfly
nym
phs
Population Size
Hig
h
Low
Population Size
Hig
h
Low
No
Fis
h F
ish
Fig
ure
58
.14
To
p-d
ow
n e
! e
cts
de
mo
nst
rate
d b
y
ex
pe
rim
en
t in
a s
imp
le t
rop
hic
ca
sca
de
. In
a N
ew Z
eala
nd
stre
am,
encl
osu
res
wit
h t
rou
t h
ad f
ewer
her
biv
oro
us
inve
rteb
rate
s
(see
th
e le
ft-h
and
pan
el)
and
mo
re a
lgae
(se
e th
e ri
gh
t-h
and
pan
el)
than
on
es w
ith
ou
t tr
ou
t.
Inq
uir
y q
ue
stio
n
?
Wh
y d
o s
tre
am
s w
ith
tro
ut
ha
ve
mo
re a
lga
e?
Fig
ure
58
.15
To
p-d
ow
n e
! e
cts
de
mo
nst
rate
d b
y a
n e
xp
eri
me
nt
in a
fo
ur-
lev
el
tro
ph
ic c
asc
ad
e.
Str
eam
en
clo
sure
s w
ith
larg
e, c
arn
ivo
rou
s #
sh (
on r
ight
) h
ave
few
er p
rim
ary
carn
ivo
res,
su
ch a
s d
amse
l" y
ny
mp
hs,
mo
re h
erb
ivo
rou
s in
sect
s (e
xem
pli
# ed
her
e b
y th
e
nu
mb
er o
f ch
iro
no
mid
s, a
ty
pe
of
aqu
atic
in
sect
), a
nd
lo
wer
lev
els
of
alg
ae.
Inq
uir
y q
ue
stio
n
?
Wh
at
mig
ht
be
th
e e
ffe
ct if
sn
ak
es
tha
t p
rey
on
fis
h w
ere
ad
de
d t
o t
he
en
clo
sure
s?
In
an
exp
erim
ent
sim
ilar
to
th
e o
ne
just
des
crib
ed, e
ncl
o-
sure
s w
ere
crea
ted
in
fre
e-fl
ow
ing
str
eam
s in
no
rth
ern
Cal
ifo
r-n
ia.
In t
hes
e st
ream
s, t
he
pri
nci
pal
pri
mar
y ca
rniv
ore
s w
ere
dam
self
ly
larv
ae
(ter
med
ny
mph
s).
Fis
h
that
p
reye
d
on
th
e n
ymp
hs
and
on
oth
er p
rim
ary
carn
ivo
res
wer
e ad
ded
to
so
me
encl
osu
res
bu
t n
ot
oth
ers.
In
th
e en
clo
sure
s w
ith
fis
h, t
he
nu
m-
ber
s o
f d
amse
lfly
n
ymp
hs
wer
e re
du
ced
, le
adin
g to
h
igh
er
nu
mb
ers
of
thei
r p
rey,
in
clu
din
g h
erb
ivo
rou
s in
sect
s, w
hic
h l
ed
in t
urn
to
a d
ecre
ased
bio
mas
s o
f al
gae
(fi
gu
re 5
8.1
5).
Tro
ph
ic c
asca
des
in la
rge-
scal
e ec
osy
stem
s ar
e n
ot
as e
asy
to v
erif
y b
y ex
per
imen
t as
on
es i
n s
trea
m e
ncl
osu
res,
an
d t
he
wo
rkin
gs
of
such
cas
cad
es a
re n
ot
tho
rou
gh
ly k
no
wn
. N
on
e-th
eles
s, c
erta
in c
asca
des
in
lar
ge-
scal
e ec
osy
stem
s ar
e re
cog
-n
ized
by
mo
st e
colo
gis
ts. O
ne
of
the
mo
st d
ram
atic
invo
lves
sea
o
tter
s, s
ea u
rch
ins,
an
d k
elp
fo
rest
s al
on
g t
he
Wes
t C
oas
t o
f N
ort
h A
mer
ica
(fig
ure
58
.16
).
T
he
ott
ers
eat
the
urc
hin
s, a
nd
th
e u
rch
ins
eat
you
ng
ke
lps,
in
hib
itin
g t
he
dev
elo
pm
ent
of
kelp
fo
rest
s. W
hen
th
e o
t-te
rs a
re a
bu
nd
ant,
th
e ke
lp f
ore
sts
are
wel
l d
evel
op
ed b
ecau
se
ther
e ar
e re
lati
vely
few
urc
hin
s in
th
e sy
stem
. Bu
t w
hen
th
e o
t-te
rs a
re s
par
se,
the
urc
hin
s ar
e n
um
ero
us
and
im
pai
r d
evel
op
-m
ent
of
the
kelp
fo
rest
s. O
rcas
(ki
ller
wh
ales
) al
so e
nte
r th
e p
ictu
re b
ecau
se i
n r
ecen
t ye
ars
they
hav
e st
arte
d t
o p
rey
inte
n-
sive
ly o
n t
he
ott
ers,
dri
vin
g o
tter
po
pu
lati
on
s d
ow
n.
Hu
ma
n r
em
ov
al o
f ca
rniv
ore
s
pro
du
ces
top
-do
wn
e!
ect
s
Hu
man
act
ivit
ies
are
bel
ieve
d t
o h
ave
had
to
p-d
ow
n e
ffec
ts in
a
nu
mb
er o
f ec
osy
stem
s, u
sual
ly b
y th
e re
mo
val
of
top
-lev
el
encl
osu
res,
th
ey w
ou
ld a
lso
cau
se c
asca
din
g e
ffec
ts.
Th
e se
c-o
nd
ary
carn
ivo
res
wo
uld
be
pre
dic
ted
to
kee
p p
op
ula
tio
ns
of
pri
mar
y ca
rniv
ore
s in
ch
eck,
wh
ich
wo
uld
lead
to
a p
rofu
sio
n o
f h
erb
ivo
res
and
a s
carc
ity
of
pri
mar
y p
rod
uce
rs.
12
20
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
Population Size
Hig
h
Low
Sea O
tters
Sea U
rchin
sK
elp
Orc
apre
dation
dri
ves
sea o
tter
popula
tion
dow
n
a.
b.
Sea O
tters
Sea U
rchin
sK
elp
Population Size
Hig
h
Low
Fig
ure
58
.16
A t
rop
hic
ca
sca
de
in
a l
arg
e-s
cale
eco
syst
em
. A
lon
g t
he
Wes
t C
oas
t o
f N
ort
h A
mer
ica,
th
e se
a o
tter
/sea
urc
hin
/kel
p
syst
em e
xist
s in
tw
o s
tate
s: I
n t
he
stat
e sh
ow
n i
n p
anel
a,
low
po
pu
lati
on
s o
f se
a o
tter
s p
erm
it h
igh
po
pu
lati
on
s o
f u
rch
ins,
wh
ich
su
pp
ress
kel
p
po
pu
lati
on
s; i
n t
he
stat
e sh
ow
n i
n p
anel
b,
hig
h p
op
ula
tio
ns
of
ott
ers
keep
urc
hin
s in
ch
eck
, p
erm
itti
ng
pro
fuse
kel
p g
row
th.
Acc
ord
ing
to
a
rece
nt
hy
po
thes
is, a
swit
ch o
f o
rcas
to
pre
yin
g o
n o
tter
s ra
ther
th
an o
ther
mam
mal
s is
lea
din
g t
he
eco
syst
em t
od
ay t
o b
e m
ost
ly i
n t
he
stat
e
rep
rese
nte
d o
n t
he
left
.
carn
ivo
res.
Th
e g
reat
nat
ura
list
Ald
o L
eop
old
po
site
d s
uch
ef-
fect
s lo
ng
bef
ore
th
e tr
op
hic
cas
cad
e h
ypo
thes
is h
ad b
een
sci
-en
tifi
call
y ar
ticu
late
d w
hen
he
wro
te i
n S
and
Cou
nty
Alm
anac
:
“I h
ave
live
d t
o s
ee s
tate
aft
er s
tate
ext
irp
ate
its
wo
lves
. I
hav
e w
atch
ed t
he
face
of
man
y a
new
wo
lfle
ss m
ou
nta
in,
and
se
en t
he
sou
th-f
acin
g s
lop
es w
rin
kle
wit
h a
maz
e o
f n
ew d
eer
trai
ls. I
hav
e se
en e
very
ed
ible
bu
sh a
nd
see
dli
ng
bro
wse
d, f
irst
to
an
emic
des
uet
ud
e, a
nd
th
en t
o d
eath
. I h
ave
seen
eve
ry e
dib
le
tree
def
oli
ated
to
th
e h
eig
ht
of
a sa
dd
le h
orn
.”
Man
y si
mil
ar e
xam
ple
s ex
ist
in w
hic
h t
he
rem
ova
l o
f p
red
ato
rs h
as l
ed t
o c
asca
din
g e
ffec
ts o
n l
ow
er t
rop
hic
lev
els.
L
arg
e p
red
ato
rs s
uch
as
jag
uar
s an
d m
ou
nta
in l
ion
s ar
e ab
sen
t o
n B
arro
Co
lora
do
Isl
and
, a h
illt
op
tu
rned
into
an
isla
nd
by
the
con
stru
ctio
n o
f th
e P
anam
a C
anal
at
the
beg
inn
ing
of
the
last
ce
ntu
ry.
As
a re
sult
, sm
alle
r p
red
ato
rs w
ho
se p
op
ula
tio
ns
are
no
rmal
ly h
eld
in
ch
eck—
incl
ud
ing
mo
nke
ys, p
ecca
ries
(a
rela
-ti
ve o
f th
e p
ig),
co
atim
un
dis
, an
d a
rmad
illo
s—h
ave
bec
om
e ex
-tr
aord
inar
ily
abu
nd
ant.
Th
ese
anim
als
eat
alm
ost
an
yth
ing
th
ey
fin
d.
Gro
un
d-n
esti
ng
b
ird
s ar
e p
arti
cula
rly
vuln
erab
le,
and
m
any
spec
ies
hav
e d
ecli
ned
; at
lea
st 1
5 b
ird
sp
ecie
s h
ave
van
-is
hed
fro
m t
he
isla
nd
en
tire
ly.
S
imil
arly
, in
th
e w
orl
d’s
oce
ans,
lar
ge
pre
dat
ory
fis
h s
uch
as
bil
lfis
h a
nd
co
d h
ave
bee
n r
edu
ced
by
ove
rfis
hin
g t
o a
n a
ver-
age
of
10
% o
f th
eir
pre
vio
us
nu
mb
ers
in v
irtu
ally
all
par
ts o
f th
e w
orl
d’s
oce
ans.
In
so
me
reg
ion
s, t
he
pre
y o
f co
d—
such
as
cert
ain
sh
rim
p
and
cr
abs—
hav
e b
eco
me
man
y ti
mes
m
ore
ab
un
dan
t th
an t
hey
wer
e b
efo
re,
and
fu
rth
er c
asca
din
g e
ffec
ts
are
evid
ent
at s
till
lo
wer
tro
ph
ic l
evel
s.
Bo
tto
m-u
p e
! e
cts
occ
ur
wh
en
ch
an
ge
s to
pri
ma
ry p
rod
uce
rs a
! e
ct h
igh
er
tro
ph
ic le
ve
ls
In p
red
icti
ng
bo
tto
m-u
p e
ffec
ts,
eco
log
ists
mu
st t
ake
acco
un
t o
f th
e li
fe
his
tori
es
of
the
org
anis
ms
pre
sen
t. A
m
od
el
of
bo
tto
m-u
p e
ffec
ts t
ho
ug
ht
to a
pp
ly t
o a
nu
mb
er o
f ty
pes
of
eco
syst
ems
is d
iag
ram
med
in
fig
ure
58
.17
.
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
22
1w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
Pri
mary
Pro
ductivity
Low
Hig
h
Biomass ofPrimary Producers L
ow
Hig
h
Biomass ofHerbivores L
ow
Hig
h
Biomass ofCarnivores L
ow
Hig
h
Inte
nsity o
f Illu
min
ation (μ
mol of
photo
ns o
f lig
ht/
m2/s
)
Carnivore Biomass (g/m2) Herbivore Biomass (g/m2) Primary Producer Biomass(g algae/m2)
12
10 8 6 4 2 0
0300
600
900
1200
1500
8 6 4 2 0
1.2
1.0
0.8
0.6
0.4
0.2 0
0300
600
900
1200
1500
0300
600
900
1200
1500
Fig
ure
58
.17
A m
od
el
of
bo
tto
m-u
p e
! e
cts
. A
t lo
w l
evel
s
of
pri
mar
y p
rod
uct
ivit
y, h
erb
ivo
re p
op
ula
tio
ns
can
no
t o
bta
in
eno
ug
h f
oo
d t
o b
e m
ain
tain
ed; w
ith
ou
t h
erb
ivo
ry, th
e st
and
ing
cro
p
bio
mas
s o
f th
e p
rim
ary
pro
du
cers
su
ch a
s th
ese
dia
tom
s in
crea
ses
as
thei
r p
rod
uct
ivit
y in
crea
ses.
Ab
ove
so
me
thre
sho
ld,
incr
ease
s in
pri
mar
y p
rod
uct
ivit
y le
ad t
o i
ncr
ease
s in
her
biv
ore
po
pu
lati
on
s an
d
her
biv
ore
bio
mas
s; t
he
bio
mas
s o
f th
e p
rim
ary
pro
du
cers
th
en d
oes
no
t in
crea
se a
s p
rim
ary
pro
du
ctiv
ity
incr
ease
s b
ecau
se t
he
incr
easi
ng
pro
du
ctiv
ity
is c
rop
ped
by
the
her
biv
ore
s. A
bo
ve a
no
ther
thre
sho
ld, p
op
ula
tio
ns
of
pri
mar
y ca
rniv
ore
s ca
n b
e su
stai
ned
. A
s
pri
mar
y p
rod
uct
ivit
y in
crea
ses
abo
ve t
his
th
resh
old
, th
e ca
rniv
ore
s
con
sum
e th
e in
crea
sin
g p
rod
uct
ivit
y o
f th
e h
erb
ivo
res,
so
th
e
bio
mas
s o
f th
e h
erb
ivo
re p
op
ula
tio
ns
rem
ain
s re
lati
vely
co
nst
ant
wh
ile
the
bio
mas
s o
f th
e ca
rniv
ore
po
pu
lati
on
s in
crea
ses.
Th
e
bio
mas
s o
f th
e p
rim
ary
pro
du
cers
is
no
lo
ng
er c
on
stra
ined
by
incr
ease
s in
th
e h
erb
ivo
re p
op
ula
tio
ns
and
th
us
also
in
crea
ses
wit
h
incr
easi
ng
pri
mar
y p
rod
uct
ivit
y. A
key
to
un
der
stan
din
g t
he
mo
del
is t
o m
ain
tain
a d
isti
nct
ion
bet
wee
n t
he
con
cep
ts o
f p
rod
uct
ivit
y
and
sta
nd
ing
cro
p b
iom
ass.
Inq
uir
y q
ue
stio
n
?
Ho
w is
it p
oss
ible
fo
r th
e b
iom
ass
of
the
pri
ma
ry p
rod
uce
rs t
o
sta
y r
ela
tiv
ely
co
nst
an
t a
s th
e p
rim
ary
pro
du
ctiv
ity
incr
ea
ses?
Fig
ure
58
.18
A
n e
xp
eri
me
nta
l st
ud
y o
f b
ott
om
-up
e!
ec
ts i
n a
riv
er
eco
syst
em
. T
his
sys
tem
, st
ud
ied
on
th
e E
el
Riv
er i
n n
ort
her
n C
alif
orn
ia, ex
hib
ited
th
e p
atte
rns
mo
del
ed b
y th
e
red
gra
ph
s o
f #
gu
re 5
8.1
7. I
ncr
ease
s in
th
e in
ten
sity
of
illu
min
atio
n
led
to
in
crea
ses
in p
rim
ary
pro
du
ctiv
ity
and
in
th
e b
iom
ass
of
the
pri
mar
y p
rod
uce
rs.
Th
e b
iom
ass
of
the
carn
ivo
re p
op
ula
tio
ns
also
incr
ease
d. H
ow
ever
, h
erb
ivo
re b
iom
ass
did
no
t in
crea
se m
uch
wit
h
incr
easi
ng
pri
mar
y p
rod
uct
ivit
y b
ecau
se i
ncr
ease
s in
her
biv
ore
pro
du
ctiv
ity
wer
e co
nsu
med
by
the
carn
ivo
res.
Inq
uir
y q
ue
stio
n
?
Wh
y is
th
e a
mo
un
t o
f li
gh
t a
n im
po
rta
nt
de
term
ina
nt
of
carn
ivo
re b
iom
ass
?
the
po
pu
lati
on
s o
f w
hic
h i
ncr
ease
in
siz
e w
hil
e ke
epin
g t
he
po
pu
lati
on
s o
f p
rim
ary
pro
du
cers
fro
m i
ncr
easi
ng
.
As
pri
mar
y p
rod
uct
ivit
y b
eco
mes
sti
ll h
igh
er,
her
biv
ore
p
op
ula
tio
ns
bec
om
e la
rge
eno
ug
h t
hat
pri
mar
y ca
rniv
ore
s ca
n
be
sup
po
rted
. F
urt
her
in
crea
ses
in p
rim
ary
pro
du
ctiv
ity
then
d
oes
no
t le
ad t
o i
ncr
ease
s in
her
biv
ore
po
pu
lati
on
s, b
ut
rath
er
to i
ncr
ease
s in
car
niv
ore
po
pu
lati
on
s.
Exp
erim
enta
l ev
iden
ce f
or
the
bo
tto
m-u
p e
ffec
ts p
re-
dic
ted
by
the
mo
del
was
pro
vid
ed b
y a
stu
dy
con
du
cted
in
en
-cl
osu
res
on
a r
iver
(fi
gu
re 5
8.1
8) .
Th
e en
clo
sure
s ex
clu
ded
la
rge
fish
(se
con
dar
y ca
rniv
ore
s). A
ro
of
was
pla
ced
ab
ove
eac
h
encl
osu
re.
So
me
roo
fs w
ere
clea
r, w
her
eas
oth
ers
wer
e ti
nte
d
to v
ario
us
deg
rees
, so
th
at th
e en
clo
sure
s d
iffe
red
in th
e am
ou
nt
of
sun
lig
ht
ente
rin
g t
hem
.
A
cco
rdin
g t
o t
he
mo
del
, w
hen
pri
mar
y p
rod
uct
ivit
y is
lo
w, p
rod
uce
r p
op
ula
tio
ns
can
no
t su
pp
ort
sig
nif
ican
t h
erb
ivo
re
po
pu
lati
on
s. A
s p
rim
ary
pro
du
ctiv
ity
incr
ease
s, h
erb
ivo
re p
op
-u
lati
on
s b
eco
me
a fe
atu
re o
f th
e ec
osy
stem
. In
crea
ses
in p
ri-
mar
y p
rod
uct
ivit
y ar
e th
en e
nti
rely
dev
ou
red
by
the
her
biv
ore
s,
12
22
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
05
1015
110
10
0
2025
Number of Invading Species
Nu
mb
er
of
Sp
ecie
s o
n P
lots
Re
sult
: A
lth
ou
gh
th
e n
um
be
r o
f su
cce
ssfu
l in
va
siv
e s
pe
cie
s is
hig
hly
va
ria
ble
, mo
re s
pe
cie
s-ri
ch p
lots
on
av
era
ge
are
inv
ad
ed
by
few
er
spe
cie
s.
Inte
rpre
tati
on
: W
ha
t m
igh
t e
xpla
in w
hy
so m
uch
va
ria
tio
n e
xist
s in
th
e
nu
mb
er
of
succ
ess
ful i
nv
ad
ing
sp
eci
es
in c
om
mu
nit
ies
wit
h t
he
sa
me
spe
cie
s ri
chn
ess
?
SC
IE
NT
IF
IC
TH
IN
KI
NG
Qu
est
ion
: D
oe
s sp
eci
es
rich
ne
ss a
ffe
ct t
he
inv
asi
bil
ity
of
a c
om
mu
nit
y?
Hy
po
the
sis:
T
he
ra
te o
f su
cce
ssfu
l in
va
sio
n w
ill b
e lo
we
r in
co
mm
un
itie
s
wit
h g
rea
ter
rich
ne
ss.
Ex
pe
rim
en
t:
Ad
d s
ee
ds
fro
m t
he
sa
me
nu
mb
er
of
no
n-n
ati
ve
pla
nts
to
exp
eri
me
nta
l plo
ts t
ha
t d
iffe
r in
th
e n
um
be
r o
f p
lan
t sp
eci
es.
a.
b.
Fig
ure
58
.19
E" e
ct o
f sp
ecies ri
chness
on
eco
system
sta
bility
. a.
On
e o
f th
e C
edar
Cre
ek e
xper
imen
tal
plo
ts.
b.
Co
mm
un
ity
stab
ilit
y ca
n b
e as
sess
ed b
y lo
ok
ing
at
the
effe
ct o
f
spec
ies
rich
nes
s o
n c
om
mu
nit
y in
vasi
bil
ity.
Eac
h d
ot
rep
rese
nts
dat
a
fro
m o
ne
exp
erim
enta
l p
lot
in t
he
Ced
ar C
reek
exp
erim
enta
l !
eld
s.
Plo
ts w
ith
mo
re s
pec
ies
are
har
der
to
in
vad
e b
y n
on
nat
ive
spec
ies.
Inquiry
question
?
Ho
w c
ou
ld y
ou
de
vis
e a
n e
xp
eri
me
nt
on
inv
asi
bil
ity
th
at
did
n’t
re
ly o
n s
pe
cie
s fr
om
su
rro
un
din
g a
rea
s?
spec
ies.
Ag
ain
, mo
re s
pec
ies-
rich
plo
ts h
ad g
reat
er y
ear-
to-y
ear
stab
ilit
y in
bio
mas
s o
ver
a 1
0-y
ear
per
iod
.
In a
rel
ated
exp
erim
ent,
wh
en s
eed
s o
f o
ther
pla
nt
spec
ies
wer
e ad
ded
to
dif
fere
nt
plo
ts,
the
abil
ity
of
thes
e sp
ecie
s to
b
eco
me
esta
bli
shed
was
neg
ativ
ely
rela
ted
to
sp
ecie
s ri
chn
ess
(fig
ure
58
.19
b). M
ore
div
erse
co
mm
un
itie
s, i
n o
ther
wo
rds,
are
m
ore
res
ista
nt
to i
nva
sio
n b
y n
ew s
pec
ies,
wh
ich
is
ano
ther
m
easu
re o
f co
mm
un
ity
stab
ilit
y.
T
he
pri
mar
y p
rod
uct
ivit
y w
as h
igh
est
in t
he
encl
osu
res
wit
h c
lear
ro
ofs
an
d l
ow
est
in t
he
on
es w
ith
dar
kly
tin
ted
ro
ofs
. A
s p
rim
ary
pro
du
ctiv
ity
incr
ease
d i
n p
aral
lel
wit
h i
llu
min
atio
n,
the
bio
mas
s o
f th
e p
rim
ary
pro
du
cers
in
crea
sed
, as
did
th
e b
io-
mas
s o
f th
e ca
rniv
ore
s. H
ow
ever
, th
e b
iom
ass
of
the
tro
ph
ic le
vel
san
dw
ich
ed in
bet
wee
n, t
he
her
biv
ore
s, d
id n
ot
incr
ease
mu
ch, a
s p
red
icte
d b
y th
e m
od
el in
fig
ure
58.
17 (
see
red
gra
ph
lin
es).
Le
arn
ing
Ou
tco
me
s R
ev
iew
58
.3
Popu
lati
ons
of s
peci
es a
t diff
ere
nt tr
ophi
c le
vels
aff
ect o
ne a
noth
er, a
nd
thes
e eff
ect
s ca
n pr
opag
ate
thro
ugh
the
leve
ls. T
op-d
own
eff e
cts,
term
ed
trop
hic
casc
ades
, are
obs
erve
d w
hen
chan
ges
in c
arni
vore
pop
ulat
ions
aff e
ct lo
wer
trop
hic
leve
ls. B
otto
m-u
p eff
ect
s ar
e ob
serv
ed w
hen
chan
ges
in
prim
ary
prod
ucti
vity
aff
ect t
he h
ighe
r tro
phic
leve
ls.
■
C
ou
ld t
op
-do
wn
an
d b
ott
om
-up
eff
ect
s o
ccu
r si
mu
lta
ne
ou
sly?
58
.4
Biodiversity
and
Ecosystem
Stability
Le
arn
ing
Ou
tco
me
s
De
fin
e e
cosy
ste
m s
tab
ilit
y.1.
De
scri
be
the
eff
ect
s o
f sp
eci
es
rich
ne
ss o
n e
cosy
ste
m
2.
fun
ctio
n.
Na
me
po
ssib
le f
act
ors
th
at
con
trib
ute
to
sp
eci
es
rich
ne
ss
3.
in t
he
tro
pic
s.
In t
he
pre
ced
ing
ch
apte
r, w
e d
iscu
ssed
spe
cies
ric
hn
ess—
the
nu
mb
er o
f sp
ecie
s p
rese
nt
in a
co
mm
un
ity.
Eco
log
ists
hav
e lo
ng
deb
ated
th
e co
nse
qu
ence
s o
f d
iffe
ren
ces
in s
pec
ies
rich
-n
ess
bet
wee
n c
om
mu
nit
ies.
On
e th
eory
is
that
sp
ecie
s-ri
ch
com
mu
nit
ies
are
mo
re s
tab
le—
that
is,
mo
re c
on
stan
t in
co
m-
po
siti
on
an
d b
ette
r ab
le t
o r
esis
t d
istu
rban
ce. T
his
hyp
oth
esis
h
as b
een
ele
gan
tly
stu
die
d b
y D
avid
Til
man
an
d c
oll
eag
ues
at
the
Un
iver
sity
of
Min
nes
ota
’s C
edar
Cre
ek N
atu
ral
His
tory
A
rea.
Spe
cies ri
chness
may
increase
sta
bility:
The
Ce
dar
Cree
k stu
dies
Wo
rker
s m
on
ito
red
2
07
sm
all
rect
ang
ula
r p
lots
o
f la
nd
(8
–16
m2)
for
11
yea
rs (
fig
ure
58
.19
a) .
In e
ach
plo
t, t
hey
co
un
ted
th
e n
um
ber
of
pra
irie
pla
nt
spec
ies
and
mea
sure
d t
he
tota
l am
ou
nt
of
pla
nt
bio
mas
s (t
hat
is, t
he
mas
s o
f al
l pla
nts
on
th
e p
lot)
. O
ver
the
cou
rse
of
the
stu
dy,
pla
nt
spec
ies
rich
nes
s w
as r
elat
ed t
o c
om
mu
nit
y st
abil
ity—
plo
ts w
ith
mo
re s
pec
ies
sho
wed
les
s ye
ar-t
o-y
ear
vari
atio
n i
n b
iom
ass.
Mo
reo
ver,
in
tw
o d
rou
gh
t ye
ars,
th
e d
ecli
ne
in b
iom
ass
was
neg
ativ
ely
re-
late
d t
o s
pec
ies
rich
nes
s—th
at is
, plo
ts w
ith
mo
re s
pec
ies
wer
e le
ss a
ffec
ted
by
dro
ug
ht.
T
hes
e fi
nd
ing
s w
ere
sub
seq
uen
tly
con
firm
ed b
y an
ex-
per
imen
t in
wh
ich
plo
ts w
ere
seed
ed w
ith
dif
fere
nt
nu
mb
ers
of
cha
pte
r 5
8 Dynamics of Ecosystem
s 1
22
3w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
a.
Pri
mary
Pro
ductivity
Plant Species Richness
Pla
nt
Str
uctu
ral C
om
ple
xity
Number of
Lizard Species
Tem
pera
ture
Range (
OC
)
Number of
Mammal Species
b.
c.
0
100
200
300
400
0
0.2
0.4
0.6
0.8
5
0
10
15
20
25
50
100
150
456789
10
30
20
10 0
Fig
ure
58
.20
Fa
cto
rs t
ha
t a
� e
ct
spe
cie
s ri
chn
ess
. a.
Pro
duct
ivit
y: I
n p
lan
t co
mm
un
itie
s o
f m
ou
nta
ino
us
area
s o
f S
ou
th A
fric
a,
spec
ies
rich
nes
s o
f p
lan
ts p
eak
s at
in
term
edia
te l
evel
s o
f p
rod
uct
ivit
y (b
iom
ass)
. b.
Spa
tial
het
erog
enei
ty: T
he
spec
ies
rich
nes
s o
f d
eser
t li
zard
s is
po
siti
vely
co
rrel
ated
wit
h t
he
stru
ctu
ral
com
ple
xity
of
the
pla
nt
cove
r in
des
ert
site
s in
th
e A
mer
ican
So
uth
wes
t. c
. C
lim
ate:
Th
e sp
ecie
s
rich
nes
s o
f m
amm
als
is i
nve
rsel
y co
rrel
ated
wit
h m
on
thly
mea
n t
emp
erat
ure
ran
ge
alo
ng
th
e W
est
Co
ast
of
No
rth
Am
eric
a.
Inq
uir
y q
ue
stio
n
?
(a.)
Wh
y is
sp
eci
es
rich
ne
ss g
rea
test
at
inte
rme
dia
te le
ve
ls o
f p
rod
uct
ivit
y? (
b.)
Wh
y d
o m
ore
str
uct
ura
lly
co
mp
lex
are
as
ha
ve
mo
re
spe
cie
s? (c
.) W
hy
do
are
as
wit
h le
ss v
ari
ati
on
in t
em
pe
ratu
re h
av
e m
ore
sp
eci
es?
S
pec
ies
rich
nes
s m
ay a
lso
aff
ect
oth
er e
cosy
stem
pro
-ce
sses
. T
ilm
an a
nd
co
llea
gu
es m
on
ito
red
14
7 e
xper
imen
tal
plo
ts t
hat
var
ied
in
nu
mb
er o
f sp
ecie
s to
est
imat
e h
ow
mu
ch
gro
wth
was
occ
urr
ing
an
d h
ow
mu
ch n
itro
gen
th
e g
row
ing
p
lan
ts w
ere
taki
ng
up
fro
m t
he
soil
. Th
ey f
ou
nd
th
at t
he
mo
re
spec
ies
a p
lot
had
, th
e g
reat
er t
he
nit
rog
en u
pta
ke a
nd
to
tal
amo
un
t o
f b
iom
ass
pro
du
ced
. In
his
stu
dy,
in
crea
sed
bio
div
er-
sity
cle
arly
ap
pea
red
to
lea
d t
o g
reat
er p
rod
uct
ivit
y.
Lab
ora
tory
stu
die
s o
n a
rtif
icia
l ec
osy
stem
s h
ave
pro
vid
ed
sim
ilar
res
ult
s. I
n o
ne
elab
ora
te s
tud
y, e
cosy
stem
s co
veri
ng
1
m2 w
ere
con
stru
cted
in
gro
wth
ch
amb
ers
that
co
ntr
oll
ed
tem
per
atu
re, l
igh
t le
vels
, air
cu
rren
ts, a
nd
atm
osp
her
ic g
as c
on
-ce
ntr
atio
ns.
A v
arie
ty o
f p
lan
ts, i
nse
cts,
an
d o
ther
an
imal
s w
ere
intr
od
uce
d t
o c
on
stru
ct e
cosy
stem
s co
mp
ose
d o
f 9
, 1
5,
or
31
sp
ecie
s, w
ith
th
e lo
wer
div
ersi
ty t
reat
men
ts c
on
tain
ing
a s
ub
set
of t
he
spec
ies
in th
e h
igh
er d
iver
sity
en
clo
sure
s. A
s w
ith
Til
man
’s
exp
erim
ents
, th
e am
ou
nt
of
bio
mas
s p
rod
uce
d w
as r
elat
ed t
o
spec
ies
rich
nes
s, a
s w
as t
he
amo
un
t o
f ca
rbo
n d
ioxi
de
con
-su
med
, an
oth
er m
easu
re o
f th
e p
rod
uct
ivit
y o
f th
e ec
osy
stem
.
Til
man
’s c
on
clu
sio
n t
hat
hea
lth
y ec
osy
stem
s d
epen
d o
n
div
ersi
ty i
s n
ot
acce
pte
d b
y al
l ec
olo
gis
ts,
ho
wev
er.
Cri
tics
q
ues
tio
n t
he
vali
dit
y an
d r
elev
ance
of
thes
e b
iod
iver
sity
stu
d-
ies,
arg
uin
g t
hat
th
e m
ore
sp
ecie
s ar
e ad
ded
to
a p
lot,
th
e g
reat
er t
he
pro
bab
ilit
y th
at o
ne
spec
ies
wil
l b
e h
igh
ly p
rod
uc-
tive
. To
sh
ow
th
at h
igh
pro
du
ctiv
ity
resu
lts
fro
m h
igh
sp
ecie
s ri
chn
ess
per
se,
rat
her
th
an f
rom
th
e p
rese
nce
of
par
ticu
lar
hig
hly
pro
du
ctiv
e sp
ecie
s, e
xper
imen
tal
plo
ts h
ave
to e
xhib
it
“ove
ryie
ldin
g”;
in
oth
er w
ord
s, p
lot
pro
du
ctiv
ity
has
to
be
gre
ater
th
an t
hat
of
the
sin
gle
mo
st p
rod
uct
ive
spec
ies
gro
wn
in
iso
lati
on
.
Alt
ho
ug
h t
his
po
int
is s
till
deb
ated
, rec
ent
wo
rk a
t C
edar
C
reek
an
d e
lsew
her
e h
as p
rovi
ded
evi
den
ce o
f o
very
ield
ing
, su
pp
ort
ing
th
e cl
aim
th
at s
pec
ies
rich
nes
s o
f co
mm
un
itie
s en
-h
ance
s co
mm
un
ity
pro
du
ctiv
ity
and
sta
bil
ity.
Sp
eci
es
rich
ne
ss is
in!
ue
nce
d
by
eco
syst
em
ch
ara
cte
rist
ics
A n
um
ber
of
fact
ors
are
kn
ow
n o
r h
ypo
thes
ized
to
aff
ect
spe-
cies
ric
hn
ess
in a
co
mm
un
ity.
We
dis
cuss
ed s
om
e in
ch
apte
r 5
7,
such
as
loss
of
keys
ton
e sp
ecie
s an
d m
od
erat
e p
hys
ical
dis
tur-
ban
ce. H
ere
we
dis
cuss
th
ree
mo
re: p
rim
ary
pro
du
ctiv
ity,
hab
i-ta
t h
eter
og
enei
ty, a
nd
cli
mat
ic f
acto
rs.
Pri
ma
ry p
rod
uct
ivit
y
Eco
syst
ems
dif
fer
sub
stan
tial
ly i
n p
rim
ary
pro
du
ctiv
ity
(see
fi
gu
re 5
8.1
1).
So
me
evid
ence
in
dic
ates
th
at s
pec
ies
rich
nes
s is
re
late
d t
o p
rim
ary
pro
du
ctiv
ity,
bu
t th
e re
lati
on
ship
bet
wee
n
them
is
no
t li
nea
r. I
n a
nu
mb
er o
f ca
ses,
fo
r ex
amp
le,
eco
sys-
tem
s w
ith
in
term
edia
te l
evel
s o
f p
rod
uct
ivit
y te
nd
to
hav
e th
e g
reat
est
nu
mb
er o
f sp
ecie
s (f
igu
re 5
8.2
0a)
.
Wh
y th
is i
s so
is
deb
ated
. On
e p
oss
ibil
ity
is t
hat
lev
els
of
pro
du
ctiv
ity
are
lin
ked
wit
h n
um
ber
s o
f co
nsu
mer
s. A
pp
lyin
g
this
co
nce
pt
to p
lan
t sp
ecie
s ri
chn
ess,
th
e ar
gu
men
t is
th
at a
t lo
w p
rod
uct
ivit
y, t
her
e ar
e fe
w h
erb
ivo
res,
an
d s
up
erio
r co
m-
pet
ito
rs a
mo
ng
th
e p
lan
ts a
re a
ble
to
eli
min
ate
mo
st o
ther
pla
nt
spec
ies.
In
co
ntr
ast,
at
hig
h p
rod
uct
ivit
y so
man
y h
erb
ivo
res
are
pre
sen
t th
at o
nly
th
e p
lan
t sp
ecie
s m
ost
res
ista
nt
to g
razi
ng
su
rviv
e, r
edu
cin
g s
pec
ies
div
ersi
ty. A
s a
resu
lt, t
he
gre
ates
t n
um
-b
ers
of
pla
nt
spec
ies
coex
ist
at in
term
edia
te le
vels
of
pro
du
ctiv
-it
y an
d h
erb
ivo
ry.
Ha
bit
at
he
tero
ge
ne
ity
Sp
atia
lly
het
ero
gen
eou
s ab
ioti
c en
viro
nm
ents
are
th
ose
th
at
con
sist
of
man
y h
abit
at t
ypes
—su
ch a
s so
il t
ypes
, fo
r ex
amp
le.
Th
ese
het
ero
gen
eou
s en
viro
nm
ents
can
be
exp
ecte
d t
o a
cco
m-
mo
dat
e m
ore
sp
ecie
s o
f p
lan
ts t
han
sp
atia
lly
ho
mo
gen
eou
s en
-vi
ron
men
ts.
Wh
at’s
mo
re,
the
spec
ies
rich
nes
s o
f an
imal
s ca
n
be
exp
ecte
d t
o r
efle
ct t
he
spec
ies
rich
nes
s o
f p
lan
ts p
rese
nt.
An
12
24
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
Num
ber
of
specie
s
0–
50
50–
100
100–
150
150–
200
200–
250
250–
300
300–
350
350–
400
400–
450
450–
500
500–
550
550–
600
600–
650
650–
700
Fig
ure
58
.21
A l
ati
tud
ina
l cl
ine
in
sp
eci
es
rich
ne
ss.
Am
on
g N
ort
h a
nd
Cen
tral
Am
eric
an b
ird
s, a
mar
ked
incr
ease
in
th
e n
um
ber
of
spec
ies
occ
urs
mo
vin
g t
ow
ard
th
e tr
op
ics.
Few
er t
han
10
0 s
pec
ies
are
fou
nd
at
arct
ic l
atit
ud
es, b
ut
mo
re t
han
60
0 s
pec
ies
live
in
so
uth
ern
Cen
tral
Am
eric
a.
exam
ple
of
this
lat
ter
effe
ct i
s se
en i
n f
igu
re 5
8.2
0b:
Th
e n
um
-b
er o
f li
zard
sp
ecie
s at
var
iou
s si
tes
in t
he
Am
eric
an S
ou
thw
est
mir
rors
th
e lo
cal
stru
ctu
ral
div
ersi
ty o
f th
e p
lan
ts.
Cli
ma
tic
fact
ors
Th
e ro
le o
f cl
imat
ic f
acto
rs i
s m
ore
dif
ficu
lt t
o p
red
ict.
On
th
e o
ne
han
d,
mo
re s
pec
ies
mig
ht
be
exp
ecte
d t
o c
oex
ist
in a
sea
-so
nal
en
viro
nm
ent
than
in
a c
on
stan
t o
ne
bec
ause
a c
han
gin
g
clim
ate
may
fav
or
dif
fere
nt
spec
ies
at d
iffe
ren
t ti
mes
of
the
year
. O
n t
he
oth
er h
and
, st
able
en
viro
nm
ents
are
ab
le t
o s
up
-p
ort
sp
ecia
lize
d s
pec
ies
that
wo
uld
be
un
able
to
su
rviv
e w
her
e co
nd
itio
ns
flu
ctu
ate.
Th
e n
um
ber
of
mam
mal
sp
ecie
s at
lo
ca-
tio
ns
alo
ng
th
e W
est
Co
ast
of
No
rth
Am
eric
a is
in
vers
ely
cor-
rela
ted
wit
h t
he
amo
un
t o
f lo
cal
tem
per
atu
re v
aria
tio
n—
the
wid
er t
he
vari
atio
n, t
he
few
er m
amm
alia
n s
pec
ies—
sup
po
rtin
g
the
latt
er l
ine
of
arg
um
ent
(fig
ure
58
.20
c).
Tro
pic
al r
eg
ion
s h
av
e t
he
hig
he
st d
ive
rsit
y,
alt
ho
ug
h r
ea
son
s a
re u
ncl
ea
r
Sin
ce b
efo
re D
arw
in, b
iolo
gis
ts h
ave
reco
gn
ized
th
at m
ore
dif
-fe
ren
t ki
nd
s o
f an
imal
s an
d p
lan
ts i
nh
abit
th
e tr
op
ics
than
th
e te
mp
erat
e re
gio
ns.
Fo
r m
any
typ
es o
f o
rgan
ism
s, t
her
e is
a
stea
dy
incr
ease
in s
pec
ies
rich
nes
s fr
om
th
e ar
ctic
to
th
e tr
op
ics.
C
alle
d a
sp
eci
es
div
ers
ity
clin
e, t
his
bio
geo
gra
ph
ic g
rad
ien
t in
n
um
ber
s o
f sp
ecie
s co
rrel
ated
wit
h l
atit
ud
e h
as b
een
rep
ort
ed
for
pla
nts
an
d a
nim
als,
incl
ud
ing
bir
ds
(fig
ure
58
.21
), m
amm
als,
an
d r
epti
les.
F
or
the
bet
ter
par
t o
f a
cen
tury
, ec
olo
gis
ts h
ave
pu
zzle
d
ove
r th
e sp
ecie
s d
iver
sity
cli
ne
fro
m t
he
arct
ic t
o t
he
tro
pic
s.
Th
e d
iffi
cult
y h
as n
ot
bee
n i
n f
orm
ing
a r
easo
nab
le h
ypo
thes
is
of
wh
y m
ore
sp
ecie
s ex
ist
in t
he
tro
pic
s, b
ut
rath
er i
n s
ort
ing
th
rou
gh
th
ese
man
y re
aso
nab
le h
ypo
thes
es. H
ere,
we
con
sid
er
five
of
the
mo
st c
om
mo
nly
dis
cuss
ed s
ug
ges
tio
ns.
Ev
olu
tio
na
ry a
ge
of
tro
pic
al r
eg
ion
s
Sci
enti
sts
hav
e fr
equ
entl
y p
rop
ose
d t
hat
th
e tr
op
ics
hav
e m
ore
sp
ecie
s th
an t
emp
erat
e re
gio
ns
bec
ause
th
e tr
op
ics
hav
e ex
iste
d
ove
r lo
ng
, un
inte
rru
pte
d p
erio
ds
of
evo
luti
on
ary
tim
e, w
her
eas
tem
per
ate
reg
ion
s h
ave
bee
n s
ub
ject
to
rep
eate
d g
laci
atio
ns.
T
he
gre
ater
ag
e o
f tr
op
ical
co
mm
un
itie
s w
ou
ld h
ave
allo
wed
co
mp
lex
po
pu
lati
on
in
tera
ctio
ns
to c
oev
olv
e w
ith
in t
hem
, fo
s-te
rin
g a
gre
ater
var
iety
of
pla
nts
an
d a
nim
als.
R
ecen
t w
ork
su
gg
ests
th
at t
he
lon
g-t
erm
sta
bil
ity
of
tro
p-
ical
co
mm
un
itie
s h
as b
een
gre
atly
exa
gg
erat
ed,
ho
wev
er.
An
ex
amin
atio
n o
f p
oll
en w
ith
in u
nd
istu
rbed
so
il c
ore
s re
veal
s th
at
du
rin
g g
laci
atio
ns,
th
e tr
op
ical
fo
rest
s co
ntr
acte
d t
o a
few
sm
all
refu
ges
su
rro
un
ded
by
gra
ssla
nd
. Th
is s
ug
ges
ts t
hat
th
e tr
op
ics
hav
e n
ot
had
a c
on
tin
uo
us
reco
rd o
f sp
ecie
s ri
chn
ess
ove
r lo
ng
p
erio
ds
of
evo
luti
on
ary
tim
e.
Incr
ea
sed
pro
du
ctiv
ity
A s
eco
nd
oft
en-a
dva
nce
d h
ypo
thes
is i
s th
at t
he
tro
pic
s co
n-
tain
mo
re s
pec
ies
bec
ause
th
is p
art
of
the
Ear
th r
ecei
ves
mo
re
sola
r ra
dia
tio
n t
han
do
tem
per
ate
reg
ion
s. T
he
arg
um
ent
is
that
mo
re s
ola
r en
erg
y, c
ou
ple
d t
o a
yea
r-ro
un
d g
row
ing
sea
-so
n,
gre
atly
in
crea
ses
the
ove
rall
ph
oto
syn
thet
ic a
ctiv
ity
of
tro
pic
al p
lan
ts.
If
we
visu
aliz
e th
e tr
op
ical
fo
rest
’s t
ota
l re
sou
rces
as
a p
ie, a
nd
its
sp
ecie
s n
ich
es a
s sl
ices
of
the
pie
, we
can
see
th
at a
la
rger
pie
acc
om
mo
dat
es m
ore
sli
ces.
Bu
t as
no
ted
ear
lier
, m
any
fiel
d s
tud
ies
hav
e in
dic
ated
th
at s
pec
ies
rich
nes
s is
hig
h-
est
at in
term
edia
te le
vels
of
pro
du
ctiv
ity.
Acc
ord
ing
ly, i
ncr
eas-
ing
p
rod
uct
ivit
y w
ou
ld
be
exp
ecte
d
to
lead
to
lo
wer
, n
ot
hig
her
, sp
ecie
s ri
chn
ess.
Sta
bil
ity/
con
sta
ncy
of
con
dit
ion
s
Sea
son
al v
aria
tio
n, t
ho
ug
h i
t d
oes
exi
st i
n t
he
tro
pic
s, i
s g
ener
-al
ly s
ub
stan
tial
ly le
ss t
han
in t
emp
erat
e ar
eas.
Th
is r
edu
ced
sea
-so
nal
ity
mig
ht
enco
ura
ge
spec
iali
zati
on
, wit
h n
ich
es s
ub
div
ided
to
par
titi
on
res
ou
rces
an
d s
o a
void
co
mp
etit
ion
. Th
e ex
pec
ted
re
sult
wo
uld
be
a la
rger
nu
mb
er o
f m
ore
sp
ecia
lize
d s
pec
ies
in
the
tro
pic
s, w
hic
h i
s w
hat
we
see.
Man
y fi
eld
tes
ts o
f th
is h
y-p
oth
esis
hav
e b
een
car
ried
ou
t, a
nd
alm
ost
all
su
pp
ort
it,
re-
po
rtin
g
larg
er
nu
mb
ers
of
nar
row
er
nic
hes
in
tr
op
ical
co
mm
un
itie
s th
an i
n t
emp
erat
e ar
eas.
Pre
da
tio
n
Man
y re
po
rts
ind
icat
e th
at p
red
atio
n m
ay b
e m
ore
in
ten
se i
n
the
tro
pic
s. I
n t
heo
ry, m
ore
in
ten
se p
red
atio
n c
ou
ld r
edu
ce t
he
imp
ort
ance
of
com
pet
itio
n,
per
mit
tin
g g
reat
er n
ich
e o
verl
ap
and
th
us
pro
mo
tin
g g
reat
er s
pec
ies
rich
nes
s.
Sp
ati
al h
ete
rog
en
eit
y
As
no
ted
ear
lier
, sp
atia
l h
eter
og
enei
ty p
rom
ote
s sp
ecie
s ri
ch-
nes
s. T
rop
ical
fo
rest
s, b
y vi
rtu
e o
f th
eir
com
ple
xity
, cre
ate
a va
-ri
ety
of
mic
roh
abit
ats
and
so
may
fo
ster
lar
ger
nu
mb
ers
of
spec
ies.
Per
hap
s th
e lo
ng
ver
tica
l co
lum
n o
f ve
get
atio
n t
hro
ug
h
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
22
5w
ww
.ra
ve
nb
iolo
gy
.co
m
Apago PDF Enhancer
a.
b.
c.
Rate
Rate
Colo
niz
ation r
ate
of
new
specie
s
Extinction
rate
of
isla
nd
specie
s
Num
ber
of
Specie
s
Colonization Rate
Extinction Rate
Isla
nd far
from
main
land S
mall
isla
nd L
arg
eis
land
Number of Bird Species
Isla
nd S
ize (
km
2)
Num
ber
of
Specie
s
Isla
nd n
ear
main
land
100
10
1000
10,0
00
100,0
00
10
100
1000
More
than 3
200 k
m f
rom
New
Guin
ea
800–
3200 k
m f
rom
New
Guin
ea
Less t
han 8
00 k
m f
rom
New
Guin
ea
Fig
ure
58
.22
Th
e e
qu
ilib
riu
m m
od
el
of
isla
nd
bio
ge
og
rap
hy
. a.
Isla
nd
sp
ecie
s ri
chn
ess
reac
hes
an
eq
uil
ibri
um
(b
lack
do
t) w
hen
the
colo
niz
atio
n r
ate
of
new
sp
ecie
s eq
ual
s th
e ex
tin
ctio
n r
ate
of
spec
ies
on
th
e is
lan
d. b.
Th
e eq
uil
ibri
um
sh
ifts
dep
end
ing
on
th
e ra
te o
f
colo
niz
atio
n, th
e si
ze o
f an
isl
and
, an
d i
ts d
ista
nce
to
so
urc
es o
f co
lon
ists
. S
pec
ies
rich
nes
s is
po
siti
vely
co
rrel
ated
wit
h i
slan
d s
ize
and
in
vers
ely
corr
elat
ed w
ith
dis
tan
ce f
rom
th
e m
ain
lan
d. S
mal
ler
isla
nd
s h
ave
hig
her
ext
inct
ion
rat
es, sh
ifti
ng
th
e eq
uil
ibri
um
po
int
to t
he
left
. S
imil
arly
,
mo
re d
ista
nt
isla
nd
s h
ave
low
er c
olo
niz
atio
n r
ates
, ag
ain
sh
ifti
ng
th
e eq
uil
ibri
um
po
int
left
war
d. c.
Th
e ef
fect
of
dis
tan
ce f
rom
a l
arg
er i
slan
d,
wh
ich
can
be
the
sou
rce
of
colo
niz
ing
sp
ecie
s, i
s re
adil
y ap
par
ent.
Mo
re d
ista
nt
isla
nd
s h
ave
few
er A
sian
Pac
i! c
bir
d s
pec
ies
than
do
nea
rer
isla
nd
s o
f th
e sa
me
size
.
Th
e e
qu
ilib
riu
m m
od
el p
rop
ose
s th
at
ex
tin
ctio
n a
nd
co
lon
iza
tio
n r
ea
ch
a b
ala
nce
po
int
Mac
Art
hu
r an
d W
ilso
n r
easo
ned
th
at s
pec
ies
are
con
stan
tly
be-
ing
dis
per
sed
to
isl
and
s, s
o i
slan
ds
hav
e a
ten
den
cy t
o a
ccu
mu
-la
te m
ore
an
d m
ore
sp
ecie
s. A
t th
e sa
me
tim
e th
at n
ew s
pec
ies
are
add
ed, h
ow
ever
, oth
er s
pec
ies
are
lost
by
exti
nct
ion
. As
the
nu
mb
er o
f sp
ecie
s o
n a
n i
nit
iall
y em
pty
isl
and
in
crea
ses,
th
e ra
te o
f co
lon
izat
ion
mu
st d
ecre
ase
as t
he
po
ol o
f p
ote
nti
al c
olo
-n
izin
g s
pec
ies
no
t al
read
y p
rese
nt
on
th
e is
lan
d b
eco
mes
de-
ple
ted
. A
t th
e sa
me
tim
e,
the
rate
o
f ex
tin
ctio
n
sho
uld
in
crea
se—
the
mo
re s
pec
ies
on
an
isl
and
, th
e g
reat
er t
he
like
li-
ho
od
th
at a
ny
giv
en s
pec
ies
wil
l p
eris
h.
A
s a
resu
lt, a
t so
me
po
int,
th
e n
um
ber
of
exti
nct
ion
s an
d
colo
niz
atio
ns
sho
uld
be
equ
al, a
nd
th
e n
um
ber
of s
pec
ies
sho
uld
th
en r
emai
n c
on
stan
t. E
very
isl
and
of
a g
iven
siz
e, t
hen
, h
as a
ch
arac
teri
stic
eq
uil
ibri
um
nu
mb
er o
f sp
ecie
s th
at t
end
s to
per
-si
st t
hro
ug
h t
ime
(th
e in
ters
ecti
on
po
int
in f
igu
re 5
8.2
2a)
—th
ou
gh
th
e sp
ecie
s co
mp
osi
tio
n w
ill
chan
ge
as s
om
e sp
ecie
s b
eco
me
exti
nct
an
d n
ew s
pec
ies
colo
niz
e.
Mac
Art
hu
r an
d
Wil
son
’s
equ
ilib
riu
m
mo
del
p
rop
ose
s th
at i
slan
d s
pec
ies
rich
nes
s is
a d
ynam
ic e
qu
ilib
riu
m b
etw
een
co
lon
izat
ion
an
d e
xtin
ctio
n. B
oth
isl
and
siz
e an
d d
ista
nce
fro
m
the
mai
nla
nd
wo
uld
aff
ect
colo
niz
atio
n a
nd
ext
inct
ion
. W
e w
ou
ld e
xpec
t sm
alle
r is
lan
ds
to h
ave
hig
her
rat
es o
f ex
tin
ctio
n
bec
ause
th
eir
po
pu
lati
on
siz
es w
ou
ld,
on
ave
rag
e, b
e sm
alle
r.
Als
o, w
e w
ou
ld e
xpec
t fe
wer
co
lon
izer
s to
rea
ch i
slan
ds
that
lie
fa
rth
er f
rom
th
e m
ain
lan
d.
Th
us,
sm
all
isla
nd
s fa
r fr
om
th
e m
ain
lan
d w
ou
ld h
ave
the
few
est
spec
ies;
lar
ge
isla
nd
s n
ear
the
mai
nla
nd
wo
uld
hav
e th
e m
ost
(fi
gu
re 5
8.2
2b)
.
Th
e p
red
icti
on
s o
f th
is s
imp
le m
od
el b
ear
ou
t w
ell
in
fiel
d d
ata.
Asi
an P
acif
ic b
ird
sp
ecie
s (f
igu
re 5
8.2
2c)
exh
ibit
a
po
siti
ve c
orr
elat
ion
of
spec
ies
rich
nes
s w
ith
isl
and
siz
e, b
ut
a n
egat
ive
corr
elat
ion
of
spec
ies
rich
nes
s w
ith
dis
tan
ce f
rom
th
e so
urc
e o
f co
lon
ists
.
wh
ich
lig
ht
pas
ses
in a
tro
pic
al f
ore
st p
rod
uce
s a
wid
e ra
ng
e o
f li
gh
t fr
equ
enci
es a
nd
in
ten
siti
es,
crea
tin
g a
gre
ater
var
iety
of
lig
ht
envi
ron
men
ts a
nd
so
pro
mo
tin
g s
pec
ies
div
ersi
ty.
Le
arn
ing
Ou
tco
me
s R
ev
iew
58
.4An
eco
syst
em is
sta
ble
if it
rem
ains
rela
tive
ly c
onst
ant i
n co
mpo
siti
on a
nd is
able
to re
sist
dis
turb
ance
. Exp
erim
enta
l fi e
ld s
tudi
es s
uppo
rt th
e co
nclu
sion
that
spe
cies
-ric
h co
mm
unit
ies
are
bett
er a
ble
to re
sist
inva
sion
by
new
spec
ies,
as
wel
l as
have
incr
ease
d bi
omas
s pr
oduc
tion
at t
he p
rim
ary
leve
l,
alth
ough
not
all
ecol
ogis
ts a
gree
wit
h th
ese
conc
lusi
ons.
Spe
cies
rich
ness
is g
reat
est i
n th
e tr
opic
s, a
nd th
e re
ason
s m
ay in
clud
e ha
bita
t var
iati
on,
incr
ease
d su
nlig
ht, a
nd lo
ng-t
erm
clim
ate
and
seas
onal
sta
bilit
y.
■
W
ha
t m
igh
t b
e th
e e
ffe
cts
on
pri
ma
ry p
rod
uct
ivit
y if
air
p
oll
uti
on
de
cre
ase
d t
he
am
ou
nt
of
sun
lig
ht
rea
chin
g
Ea
rth
’s s
urf
ace
?
58
.5
Isla
nd
Bio
geo
gra
ph
y
Le
arn
ing
Ou
tco
me
s
De
scri
be
the
spe
cie
s–a
rea
re
lati
on
ship
.1.
Exp
lain
ho
w a
rea
an
d is
ola
tio
n a
ffe
ct r
ate
s o
f 2
. co
lon
iza
tio
n a
nd
ex
tin
ctio
n.
On
e o
f th
e m
ost
rel
iab
le p
atte
rns
in e
colo
gy
is t
he
ob
serv
atio
n
that
lar
ger
isl
and
s co
nta
in m
ore
sp
ecie
s th
an d
o s
mal
ler
is-
lan
ds.
In
19
67
, Ro
ber
t M
acA
rth
ur
of
Pri
nce
ton
Un
iver
sity
an
d
Ed
war
d O
. W
ilso
n o
f H
arva
rd U
niv
ersi
ty p
rop
ose
d t
hat
th
is
spec
ies–
area
rel
atio
nsh
ip w
as a
res
ult
of
the
effe
ct o
f g
eo-
gra
ph
ic a
rea
and
iso
lati
on
on
th
e li
keli
ho
od
of
spec
ies
exti
nc-
tio
n a
nd
co
lon
izat
ion
.
12
26
p
art
VII
I Ec
olo
gy
an
d B
eha
vio
r
Apago PDF Enhancer
Th
e e
qu
ilib
riu
m m
od
el i
s st
ill b
ein
g t
est
ed
Wil
son
an
d D
an S
imb
erlo
ff, t
hen
a g
rad
uat
e st
ud
ent,
per
form
ed
init
ial s
tud
ies
in t
he
mid
-1960s
on
sm
all m
angro
ve is
lan
ds
in t
he
Flo
rid
a ke
ys. T
hes
e is
lan
ds
wer
e ce
nsu
sed
, cle
ared
of
anim
al li
fe
by
fum
igat
ion
, an
d t
hen
all
ow
ed t
o r
eco
lon
ize,
wit
h c
ensu
ses
bei
ng p
erfo
rmed
at
regu
lar
inte
rval
s. T
hes
e an
d o
ther
su
ch f
ield
st
ud
ies
hav
e te
nd
ed t
o s
up
po
rt t
he
equ
ilib
riu
m m
od
el.
L
on
g-t
erm
exp
erim
enta
l fi
eld
stu
die
s, h
ow
ever
, ar
e su
g-
ges
tin
g t
hat
th
e si
tuat
ion
is
mo
re c
om
pli
cate
d t
han
Mac
Art
hu
r an
d W
ilso
n e
nvi
sio
ned
. T
hei
r m
od
el p
red
icts
a h
igh
lev
el o
f sp
ecie
s tu
rno
ver
as s
om
e sp
ecie
s p
eris
h a
nd
oth
ers
arri
ve.
Bu
t st
ud
ies
of
isla
nd
bir
ds
and
sp
ider
s in
dic
ate
that
ver
y li
ttle
tu
rn-
ove
r o
ccu
rs f
rom
yea
r to
yea
r. T
ho
se s
pec
ies
that
do
co
me
and
g
o,
mo
reo
ver,
co
mp
rise
a s
ub
set
of
spec
ies
that
nev
er a
ttai
n
hig
h p
op
ula
tio
ns.
A s
ub
stan
tial
pro
po
rtio
n o
f th
e sp
ecie
s ap
-p
ear
to m
ain
tain
hig
h p
op
ula
tio
ns
and
rar
ely
go
ext
inct
.
T
hes
e st
ud
ies
hav
e b
een
go
ing
on
fo
r a
rela
tive
ly s
ho
rt
per
iod
of
tim
e. I
t is
po
ssib
le t
hat
ove
r p
erio
ds
of
cen
turi
es, t
he
equ
ilib
riu
m m
od
el i
s a
go
od
des
crip
tio
n o
f w
hat
det
erm
ines
is
lan
d s
pec
ies
rich
nes
s.
Le
arn
ing
Ou
tco
me
s R
ev
iew
58
.5Th
e sp
ecie
s–ar
ea re
lati
onsh
ip is
an
obse
rvat
ion
that
an
isla
nd o
f lar
ger a
rea
cont
ains
mor
e sp
ecie
s. S
peci
es ri
chne
ss o
n is
land
s ap
pear
s to
be
a dy
nam
ic
equi
libri
um b
etw
een
colo
niza
tion
and
ext
inct
ion.
Dis
tanc
e fr
om a
mai
nlan
d
also
aff
ects
the
rate
s of
col
oniz
atio
n an
d ex
tinc
tion
, and
ther
efor
e fe
wer
spec
ies
wou
ld b
e fo
und
on s
mal
l, is
olat
ed is
land
s fa
r fro
m a
mai
nlan
d.
■
U
nd
er
wh
at
circ
um
sta
nce
s w
ou
ld a
sm
all
er
isla
nd
be
e
xpe
cte
d t
o h
ave
mo
re s
pe
cie
s th
an
a la
rge
r is
lan
d?
58
.1
Bio
ge
och
em
ica
l Cy
cle
s
Th
e a
tom
ic c
on
stit
ue
nts
of
ma
tte
r cy
cle
wit
hin
eco
syst
em
s.
Th
e at
om
s o
f ch
emic
al e
lem
ents
mo
ve t
hro
ug
h e
cosy
stem
s in
b
iog
eoch
emic
al c
ycle
s.
Ca
rbo
n, t
he
ba
sis
of
org
an
ic c
om
po
un
ds,
cyc
les
thro
ug
h
mo
st e
cosy
ste
ms.
Th
e ca
rbo
n c
ycle
usu
ally
in
volv
es c
arb
on
dio
xid
e, w
hic
h i
s !
xed
th
rou
gh
ph
oto
syn
thes
is a
nd
rel
ease
d b
y re
spir
atio
n. C
arb
on
is
also
p
rese
nt
as b
icar
bo
nat
e io
ns
and
as
met
han
e. B
urn
ing
of
foss
il f
uel
s h
as c
reat
ed a
n i
mb
alan
ce i
n t
he
carb
on
cyc
le (
see
! g
ure
58
.1).
Th
e a
vail
ab
ilit
y o
f w
ate
r is
fu
nd
am
en
tal t
o t
err
est
ria
l eco
syst
em
s.
Wat
er e
nte
rs t
he
atm
osp
her
e vi
a ev
apo
rati
on
an
d t
ran
spir
atio
n a
nd
re
turn
s to
th
e E
arth
’s s
urf
ace
as p
reci
pit
atio
n. I
t is
bro
ken
do
wn
d
uri
ng
ph
oto
syn
thes
is a
nd
als
o p
rod
uce
d d
uri
ng
cel
lula
r re
spir
atio
n.
Mu
ch o
f th
e E
arth
’s w
ater
, in
clu
din
g t
he
gro
un
dw
ater
in
aq
uif
ers,
is
po
llu
ted
, an
d h
um
an a
ctiv
itie
s al
ter
the
wat
er s
up
ply
of
eco
syst
ems
(see
! g
ure
58
.2).
Th
e n
itro
ge
n c
ycle
de
pe
nd
s o
n n
itro
ge
n "
xati
on
by
mic
rob
es.
Nit
roge
n is
usu
ally
th
e el
emen
t in
sh
ort
est
sup
ply
eve
n t
ho
ugh
N2
mak
es u
p 7
8% o
f th
e at
mo
sph
ere.
Nit
roge
n m
ust
be
con
vert
ed in
to
usa
ble
fo
rms
by
nit
roge
n-!
xin
g m
icro
org
anis
ms.
Hu
man
use
of
nit
rate
s in
fer
tili
zers
has
do
ub
led
th
e av
aila
ble
nit
roge
n (
see
! gu
re 5
8.4)
.
Ph
osp
ho
rus
cycl
es
thro
ug
h t
err
est
ria
l an
d a
qu
ati
c e
cosy
ste
ms,
bu
t n
ot
the
atm
osp
he
re.
Ph
osp
ho
rus,
an
oth
er l
imit
ing
nu
trie
nt,
is
rele
ased
by
wea
ther
ing
o
f ro
cks;
it
# o
ws
into
th
e o
cean
s w
her
e it
is
dep
osi
ted
in
dee
p-s
ea
sed
imen
ts. H
um
ans
also
use
ph
osp
hat
es a
s fe
rtil
izer
s (s
ee !
gu
re 5
8.5
).
Lim
itin
g n
utr
ien
ts in
eco
syst
em
s a
re t
ho
se in
sh
ort
su
pp
ly r
ela
tiv
e
to n
ee
d.
Th
e cy
cle
of
a li
mit
ing
nu
trie
nt,
su
ch a
s n
itro
gen
, det
erm
ines
th
e ra
te
at w
hic
h t
he
nu
trie
nt
is m
ade
avai
lab
le f
or
use
.
Bio
ge
och
em
ica
l cyc
lin
g in
a f
ore
st e
cosy
ste
m h
as
be
en
st
ud
ied
exp
eri
me
nta
lly.
On
go
ing
exp
erim
ents
in
dic
ate
that
sev
ere
dis
turb
ance
of
an
eco
syst
em r
esu
lts
in m
iner
al d
eple
tio
n a
nd
ru
no
ff o
f w
ater
.
58
.2
Th
e F
low
of
En
erg
y in
Eco
syst
em
s
En
erg
y ca
n n
eit
he
r b
e c
rea
ted
no
r d
est
roye
d, b
ut
cha
ng
es
form
.
En
erg
y ex
ists
in
fo
rms
such
as
lig
ht,
sto
red
ch
emic
al-b
on
d e
ner
gy,
m
oti
on
, an
d h
eat.
In
an
y co
nve
rsio
n, s
om
e en
erg
y is
lo
st.
Liv
ing
org
an
ism
s ca
n u
se m
an
y fo
rms
of
en
erg
y, b
ut
no
t h
ea
t.
Th
e S
eco
nd
Law
of
Th
erm
od
ynam
ics
stat
es t
hat
wh
enev
er
org
anis
ms
use
ch
emic
al-b
on
d o
r li
gh
t en
erg
y, s
om
e o
f it
is
inev
itab
ly
con
vert
ed t
o h
eat
and
can
no
t b
e re
trie
ved
.
En
erg
y #
ow
s th
rou
gh
tro
ph
ic le
ve
ls o
f e
cosy
ste
ms.
Org
anic
co
mp
ou
nd
s ar
e sy
nth
esiz
ed b
y au
totr
op
hs
and
are
uti
lize
d
by
bo
th a
uto
tro
ph
s an
d h
eter
otr
op
hs.
As
ener
gy
pas
ses
fro
m
org
anis
m t
o o
rgan
ism
, eac
h l
evel
is
term
ed a
tro
ph
ic l
evel
, an
d t
he
seq
uen
ce t
hro
ug
h p
rog
ress
ive
tro
ph
ic l
evel
s is
cal
led
a f
oo
d c
hai
n
(see
! g
ure
58
.8).
Th
e b
ase
tro
ph
ic l
evel
in
clu
des
th
e p
rim
ary
pro
du
cers
; h
erb
ivo
res
that
co
nsu
me
pri
mar
y p
rod
uce
rs a
re t
he
nex
t le
vel.
Th
ey i
n t
urn
ar
e ea
ten
by
pri
mar
ily
carn
ivo
res,
wh
ich
may
be
con
sum
ed b
y se
con
dar
y ca
rniv
ore
s. D
etri
tivo
res
feed
on
was
te a
nd
th
e re
mai
ns
of
dea
d o
rgan
ism
s.
On
ly a
bo
ut
1%
of
the
sola
r en
erg
y th
at i
mp
ing
es o
n t
he
Ear
th i
s ca
ptu
red
by
ph
oto
syn
thes
is. A
s en
erg
y m
ove
s th
rou
gh
eac
h t
rop
hic
le
vel,
very
lit
tle
(ap
pro
xim
atel
y 1
0%
) re
mai
ns
fro
m t
he
pre
ced
ing
tr
op
hic
lev
el (
see
! g
ure
58
.10
).
Th
e n
um
be
r o
f tr
op
hic
lev
els
is li
mit
ed
by
en
erg
y a
vail
ab
ilit
y.
Th
e ex
po
nen
tial
dec
lin
e o
f en
erg
y b
etw
een
tro
ph
ic l
evel
s li
mit
s th
e le
ng
th o
f fo
od
ch
ain
s an
d t
he
nu
mb
ers
of
top
car
niv
ore
s th
at c
an
be
sup
po
rted
.
Ch
ap
ter
Re
vie
w
cha
pte
r 5
8
Dyn
am
ics
of E
cosy
stem
s 1
22
7w
ww
.ra
ve
nb
iolo
gy
.co
m