m
h
ra
of
v
i
a
ch
b
d
r
tween
biotic
realm
and
Bl)
in
the
Am
and
in
tem
bel
20°
As
Fig
ure
B2
sug
a
g
ma
of
lo
deser
biom
A
b
is
a
k
iom
ind
m
a
fe
o
l
w
n
i
map
of
tem
wo
lea
Earth
are
show
in
Figu
Bl.
su
an
de
b
C
ex
w
c
m
u
o
t
a
mes
of
thes
clim
zon
ten
Bl),
as
seen
from
spac
(Fig
betwe
this
view
from
FIGU
B
1G
distr
of
the
maj
land
bio
(So
lob
H.]
de
an
P.
O.
M
1996,
Phys
Geog
of
Glob
Env
New
Yo
Wi
Fig
27
29
-B
Fore
ore
\
BIOMES
\
1[~RTH/S
\
Similar
environments
lead to evo-
lution of organisms
similar in
form and function but not neces-
sarily in genetic heritage (see
Chapter 7 for the distinction
bebiomes).
For
example,
deserts
occur on all continents except
Antarctica. Major desert plants of
each continent often look similar
but have different genetic heritage (see discussion of deserts
later in this section). Deserts
form
a category
with
the
average
summer
cold or dry climates do not per-
tem-
perature
also measured
from
space (Figure B3). This pattern
can be seen from space using
satellite remote sensing (Figure
B8). Note, for example,
the correspondence
between
July average temperatures
above 30°C
(Figure B3) and deserts (Figure
Africa. And note the correspondence between
the location of
boreal
forests
precipitation,
of
ecosystem.
Major
biomes
close
relationship
environment
forms
between
and kinds
is illustrated
of life-
in Figure
B2.
The distribution
of biomes gives
Earth a distinctive
pattern (Figure
Note
III
the
!;;;;d Desert
!!!!!!!!!!!!I
lands
mz::J
correspondence
Tropical Rainforest
(includingmonsoonforestlDTropicalSavanna
B8).
Tundra
with
tween
climate
Warm,
wet
vegetation
correlations
and
climates
different
bio-
ent average rates of vegetation
production (Figure B4). Knowledge of climate can be used to
predict what kinds of vegetation
are likely to be found in a region. Vegetation is the form of
life most visible from space, but
other forms of life have similar
each
refined
Therefore
the
of
to more
The
combined
growth.
geographic relationships.
Knowledge of basic characteristics of the world's major bio-
and July average
of ecosystem.
Ecologists call this category the
DTemperateGrasslandDTemperateForest~Temperateshrub
II
Dice
il1
CHAJ>JER1BASICISSUESINENVIRONMENTALSCIENCES
114
be-
is important
dealing
with
for planning,
environmental
is-
vegetation.
favor
production,
high
introductions
of
new
species.
For
and bio-
correlation
to be highly productive-as
long
as other factors such as availabil-
ity of chemical elements that
plants require, are not limiting;
between
geography
of climate and geography of life
to forecast possible effects of
global warming on the geography of life. Biomes are usually
"
EB
1
FIGU
82
Simp
diag
of
the
rela
betw
pre
and
lat
an
Ea
m
l
b
H
l
a
H.].
deBli
and
P.
O.
Mull
1996
Phy
Geo
of
the
Glo
En
W
N
Y
F
2
p
2
i
e
name
for
the
dom
vege
Arc
tund
typ
hav
im
port
larg
ma
as
we
ga
in
so
ar
is
a
l
i
versu
warm
deser
sma
rod
and
ins
Al
low
rainfa
and
low
aver
temperatu
(Figu
BS).
(Fig
B1
and
B3
sugg
that
arcti
tund
perm
are
ma
be
per
sm
tre
ty
u
3
m
There
are
two
kind
of
tunvery
long
tim
to
rec
As
the
~
!Ii
~
II<
tude serves as an index of average temperature,
tion (e.g., coniferous forests as
opposed to grasslands), for the
dominant
the
shape
and
physiognomy)
nant
form
of the
organisms
(forest
(called
so "latitude" can be replaced by "average temperature"
latitudes, and alpine, which occurs at high elevations. The vegetation of both is similar, but the
dominant animals are different.
harsh, the vegetation
grades
from dwarf shrubs and grasslike
as
tica, where the major land or-
domi-
versus
shrub land), or for the dominant
climatic conditions (cold desert
important
small
mammals,
birds, and insects; in alpine tundras, the dominant animals are
plants to mosses and lichens,
and finally to bare rock surfaces
with occasional lichens. The extreme tundra occurs in Antarc-
that
grows
below
Tundra
Tundras are treeless plains that
occur under the harsh climates of
tundras
occupy comparatively
small, isolated
areas, whereas
arctic tundras cover the large territories required
for populations
of large mammals.
Parts of tundra have per-
in the
where
ture
northern
hemisphere
the July
is 15°C
average
or lower.)
occurs
tempera-
The
domi-
nant vegetation includes grasses
and their relatives (sedges),
mosses, lichens, flowering dwarf
shrubs, and mat-forming plants.
mafrost, which is permanently
frozen ground.
Such areas are
extremely
fragile ecologically;
when disturbed
by such activities as the development
of roads,
nently
changed
Taiga,
dra: arctic,
which
- --- --
occurs
at high
environment
within
the
rocks,
just
surface.
or Boreal
Forests
The taiga biome includes the
forests of the cold climates of
high latitudes and high altitudes.
Taiga forests are dominated by
conifers, especially spruces, firs,
and larches, and certain kinds of
pines. Aspens and birches are
important flowering trees (Figure
B6). Boreal forests are characterized by dense stands of relatively
or may take a
which
--
in this diagram. (Source:
becomes
more
make
form
walking
dense
shade
difficult.
and
Although
EAR
BIOM
FIGU
83
Mean
sea-l
air
temp
(OC
for
July
(So
H.]
de
an
P.
0
M
1966
Phys
Geog
of
the
Glo
Env
Wi
Ne
Yo
Fig
893
areas
relati
few
impo
amo
the
mo
eco
FIGU
84
Geog
of
vege
prod
The
diff
bio
are
ch
by
and
temp
decid
fore
are
high
pro
Thi
is
ano
wa
tha
we
ca
se
the
relati
betw
clim
and
biom
(So
H.]
deB
and
P.
O.
M
19
Ph
D
Lessl
boreal
forests
cover
very large
species of trees occur. There are
only about 20 major tree species
in North American boreal forests,
different
cal
average
Geography
rates
of the
of the production
Global
Environment,
for example.
Boreal
forests
ern areas
are
important
biomes as they are the
source of much lumber and
paper
pulp.
of vegetation.
Because
Tropical
Wiley,NewYork,Figure
the north-
forests,
temperate
26-3,p.
of North
America
and
Eurasia have been connected
by
land bridges during past ice
ages, the animals and vegetation
of this biome have been able to
rain forests,
281.)
",
PACIFIC
0'
I...""y;~
[I
OCEAN1500-2000gramsperm'Cd500-1499gramsperm'D110-499gramsperm'
Ji!j
JULY-"'~-~-.--,_."",-'"u".~-,..---u-----u-~~-~~--~---"--""'-
176
,.,I
E
B
1
fow
and
car
lan
bir
vo
in
de
T
l
d
o
such
as
owl
and
eag
sit
of
la
m
re
i
iary
D
turb
c
e
s
par
s
cuI
ad
y
gr
to
ar
sm
m
in
Wa
Can
Are
of
so
or
an
sm
p
dec
tree
com
spe
an
w
ce
T
a
tal
th
70
m
a
l
o
n
FIGU
85
Tund
biom
Arct
tunsprea
wide
Moo
for
exam
mam
(moo
deer
wolv
and
bears
smal
rode
(squ
rels
rabbi
carn
FIG
86
The
bor
for
and
am
acm
othboh
,
common
~-~~~~~~G'*
fires, storms,
insects-are
""
:
~p~
~
"'."
*,>,
f
,, ,
,
'\~"
,,
""
and outbreaks
of
common
in the bo-
part
taiga;
herbi-
from
the
deep
shade
of the
forest interior; there is less for
0
real forests. For example,
the entire million acres of the Bound-
feed
Minnesota
those
burns
over (through
somewhat
important
hardwood
warmer
than
economically for their
trees used for furni-
ture. Temperate deciduous
forests are among the biomes
most changed by human beings
because they occur in regions
long dominated by civilization.
In the temperate deciduous
forest, large mammals are less
Eurasia share both genetic heritage and similar shapes and
The
dominant
forests
include
animals
of
a few large
vores (foxes), many insects, and
migratory birds, especially water-
animals
that live in trees
(such
as
Temperate
Forests
forests occur in cli-
are maples, beeches, oaks, hickories, and chestnuts, typically
larger in stature than trees of the
boreal forest. These forests are
ple, are found in both continents. In this case, the boreal
forests of North America and
dominant
Temperate
mates
National
Park, Alaska,
avens in bloom.
The
squirrels) and those that feed on
those of the boreal forest. These
forests occur throughout North
America, Eurasia, and Japan and
have many genera in common.
Dominant vegetation includes tall
dra in Denali
with mountain
on.
numerous small fires) an average
of once each century, and individual forest stands are rarely
more than 90 years old.
Temperate
boreal
in the
.
form.
,'"~"
", "~ftt
,
than
$
(such as mice). Birds and insects
are abundant.
Rain
Forests
Temperate rain forests occur
under moderate temperature
regimes where the rainfall exceeds 250 em/year. Such rain
forests are rare but spectacular;
these are the giant forests (Figure B7). In the Northern Hemisphere, the dominant trees are
evergreen
conifers.
This biome
includes the redwood
forests of
California and Oregon, where
the tallest trees in the world
exist. It also includes forests of
the state of Washington and adjacent Canada, dominated by
such large trees as Douglas-firs
lived;
Douglas-firs
live
more
than
400 years. Temperate rain forests
also occur in the Southern Hemi-
EAR
BIOM
are
the
fore
of
we
Ne
of
us
fo
re
S
Am
oc
fr
N
E
co
di
to
w
pe
sh
la
o
A
d
low
ra
th
is
co
FIGU
87
Temp
rain
fore
biome
Moss
cove
Sitka
spru
in
dom
by
sm
tree
suc
as
FIGU
88
NAS
Land
imag
of
the
veg
of
Ear
fro
spa
(Fr
"T
En
E
am
sF
to
the
lOath
anniv
issue
Nati
Geo
Ma
198
Th
sam
m
cbe
ob
fr
G
H
a
178
sphere,
the best
known
of which
Zealand.
Temperate
rain forests
comparatively
low diversity
have
of
plants and animals, in part because the climatic conditions
tend to favor specialized species,
in part because the abundant
growth
of the dominant
vegeta-
oaks. The stands tend to be
open, allowing considerable
light to reach the ground. These
generally pleasant areas are
pines
are
typical
of many
perate woodlands
tem-
and, in North
land south to Georgia and the
Caribbean islands. Fires are a
tion produces a very deep shade
in which few other plants can
grow to provide
food for herbivores.
This
biome
economically;
is important
redwoods,
glas-firs, and western
major
crops.
North
Temperate
American
Olympic
National
Park,
a famous
exam-
timber
Woodlands
Goddard
Space
Flight
Center,
Code
forests, but the climate is slightly
drier. Temperate woodlands are
pinyon
623, Greenbelt,
pines
MD.)
species
are
Temperate
Under
adapted.
Shrub
still
drier
Lands
climates
tem-
Dou-
cedars are
Temperate woodlands occur
where the temperature patterns
are like those of deciduous
ple of the temperate rain forest of the
Pacific Northwest of North America.
many
and evergreen
tinctive
feature
of this
biome
is
the chaparral, a miniature
woodland dominated by dense
stands of shrubs that rarely exceed a few meters in height.
Chaparrals occur in Mediter-
ranean
climates,
in the cool
season.
climates
with
Chaparrals
are found along the coast of
California, in Chile, in South
Africa, and in the Mediterranean
E
B
1
mamm
reptil
and
smal
are
chara
the
scent
of
sage;
some
scien
tists
believ
the
arom
com
FIG
89
Tem
gra
bio
Th
Gr
A
P
w
o
dead
twigs
and
branc
As
a
result
stand
are
rarel
more
rates
can
incre
to
some
of
the
teb
ar
ab
an
s
to
be
ve
lo
in
nu
M
mes
occ
In
the
we
clitoo
moist
for
deser
A
m
ajo
rai
w
ra
re
ma
ch
el
n
south
Afric
and
the
pam
flowe
plant
many
of
whic
of
tree
with
a
f
squ
kil
ew
kind
of
plan
som
like
pal
low
ra
tr
sa
BIO
Man
spe
of
ani
tree
but
som
are
gro
region.
There
are
few
large
Typically,
the vegetation
is
distinctively
aromatic,
such as
pounds are a means of competition among the plants. Its
animals and plants have little
economic
value at present,
but
this biome is important
for wa-
tersheds and erosion control. Be-
cause they occur in climates desirable for settlement, chaparrals
are undergoing rapid change by
human activities. The vegetation
is adapted
to fires; many species
regenerate
rapidly, and some promote
abundant
fires by producing
fuel in the form of
than 50 years old. When intense
precipitation
follows fire, erosion
highest
known,
until
renewed
vegetation again protects the
slopes. Managing fires in chaparral is especially important because housing is often near the
fire-prone vegetation.
of the world's largest areas of temperate
ment of North America.
American West; the kangaroos of
Australia; and the antelope and
other large herbivores of Africa.
Temperatures
Temperate grasslands occur in
regions too dry for forests and
biome
in
terms
of
area
covered,
these grasslands include tl1e
great North American prairies
(Figure B9), the steppes of Eurasia, the plains of eastern and
of
South
America.
Dominant
species are grasses and other
are perennials
Rain
Forests
Where the average temperature
is high and relatively constant
throughout the year, tropical biomates
and
in climates
with
rain-
dwellers.
Insects
and other
settle-
inver-
a high diversity.
Rain forests
occur in some of the most remote
regions
main
poorly
of Earth
known;
and re-
many
undiscovered species are believed to exist there.
Except for dead organic
matter at the surface, soils tend
chemical
elements
(nutrients)
are
held in the living vegetation,
which has evolved to survive in
this
environment;
otherwise,
the year are found the tropical
rain forests of South and Central
America, northeastern Australia,
Indonesia, the Philippines, Borneo, Hawaii, and parts of
Malaysia. Species diversity is
high, with hundreds of species
with extensively
developed roots.
Soils often have a deep organic layer. The highest abundance and the greatest diversity
of large mammals are found in
grasslands: the wild horses,
asses, and antelope of Eurasia;
the once-huge herds of bison
that roamed the prairies of the
I
sim-
fallwelldistributedthroughout
Grasslands
moderate,
ilar to those of the temperate deciduous forests, and rainfall is
usually seasonal.
Tropical
Temperate
are
grasslands, prior to European
meters.
Typically,
some
trees
are
very tall, but there are many
trees
ers,
ferns,
occur;
remain
like
relatively
bromeliads
grow
on
mammals
small;
and
trees
tend
for
Tropical
Forests
life.
Seasonal
and Savannas
Tropical seasonal forests occur
where rainfall is high but very
seasonal, in India and Southeast
Asia, Africa, and South and Central America. In areas of even
oth-
some
nas-grasslands
(Figure
to live
sary
in
with
scattered
trees-are
found. These include
the savannas of Africa, which,
along with the grasslands, have
the greatest abundance of large
EAR
BIOM
FIGU
810
Trop
rain
fores
biom
The
veg
alo
the
Seg
Ri
mamm
rema
anyw
in
the
world
The
numb
of
plan
beco
very
pro
Di
ban
are
com
in
the
for
Austr
occu
at
low
latitu
FIG
811
Des
bio
De
lan
at
W
Sa
N
M
New
Mex
var
gre
in
the
am
of
ve
th
c
This
dese
is
rela
spa
bu
som
ha
no
180
illustrates
lowland
tropical
rain forests.
Asia. Most deseIts have a consid-
species
is high.
Disturbances, including
fires and the impact of herbivory
on the vegetation, are common
but may be necessary to maintain these areas as savannas; otherwise, they would revert to
woodlands in wetter areas or to
shrub lands in drier areas. Under
still drier climates, savannas are
replaced by shrub lands, characterized by small shrubs, a generally low abundance of vegetation, and a low density of
vertebrate
erable amount of specialized
vegetation, as well as specialized
vertebrate and invertebrate animals. Soils often have abundant
nutrients but little or no organic
matter and need only water to
of occasional fires, occasional
cold weather, and sudden, infrequent, and intense rains that
cause flooding.
There
large
dominant
are relatively
mammals
animals
in deserts.
of
few
The
warm
deserts are nonmammalian
veIte-
brates (snakes and reptiles).
'"
:
t..
..;;:;:-"P
-""~D~
in Borneo
animals.
Deserts
Deserts occur where the rainfall
is less than 50 em/year. Although
most deserts, such as the Sahara
of North Africa and the deserts
of the southwestern United
States (Figure Bll),
Mexico, and
cold deserts occur in the basin
J
and range area of Utah and
Nevada and in parts of western
~I
E
B
1
Mam
are
usua
smal
like
decay
takes
place
slow
and
only
FIG
B
1
We
bio
We
inc
2
ar
of
op
st
w
9.8(a)
and
(b).)
Swam
and
rangi
from
smal
trees
such
as
ians
few
mam
are
exc
larg
swa
of
wa
reg
chang
in
eleva
mak
a
small
trees
can
grow
in
lowe
sma
upla
are
Earth
land
area,
they
are
imbiosp
Over
geolo
time
breed
areas
for
many
ocea
anima
and
conta
man
inve
FIG
B
1
Fre
bio
Th
Gr
3
La
of
N
A
a
Min
Cas
Pic
Ro
Na
th
sh
trb
the kangaroo
mice
American
deserts.
of North
Wetlands
Wetlands include freshwater
swamps, marshes, bogs and saltwater marshes. All have standing
water: the water table is at the surface, and the ground is saturated
with water (Figure BIZ). Standing
water creates a special soil environment
with little oxygen,
111
~i
so
plants with specialized
roots can
survive. Bogs-wetlands
with a
stream input but no surface water
outlet-are
characterized
by float-
ing mats of vegetation.
marshes
are wetlands
(See Figure
with
III
and areas of herbs, grasses, shrubs, and trees that can withstand
frequent flooding.
of
warm
or
surface
inlets and outlets.
Dominant plants are small,
mangroves
persistent
coastal
wet-
lands to black spruces and
larches of the north, to shrubs,
sedges, and mosses. Small
great difference; on slight rises,
roots can obtain oxygen and
Dominant
animals
in fresh-
Fresh
water wetlands
are many species
of insects, birds, and amphibinhabitants
of this
biome.
Although
ponds,
Waters
freshwater
rivers,
and
lakes,
streams
make
up a very small portion of
Earth's surface, they are critical
for our water supply for homes,
industry, and agriculture and
play important ecological roles
(Figure B13). They are major
recreational resources but are
The
are famous for large reptiles and
snakes, as well as for a relatively
high diversity of mammals
where
topographic
variation
allows
easily polluted.
areas are patches of open water
with algae and mosses.
Although wetlands occupy
a relatively small portion of
Dominant
plants
portant in the biosphere. In the
oxygenless soils, bacteria survive
that cannot live in high-oxygen
atmospheres. These pacteria
carry out chemical reactions,
such as the production of
methane and hydrogen sulfide,
that have important effects in the
wetland
environments
produced
the vegetation that today is coal.
Saltwater marshes are important
tebrates.
Dominant
animals
in-
clude crabs and shellfish, such as
clams.
therefore
resource.
SaltWater
an
marshes
important
are
the
world's
most
famous
examples
of the
freshwater
biome.
In this
economic
the waters of the lake and the adjacent forests is clearly illustrated.
picture,
at
.
:
EAR
BIOM
in
shallo
areas
are
roote
flow
Open
water
have
many
smal
ope
wat
of
mu
of
the
In
so
ar
de
w
a
rusdes
wit
low
River
and
strea
are
imfro
sh
T
fe
u
mal
occ
but
at
low
den
abund
of
fish.
They
are
importa
as
breed
sites
for
man
dark
and
life
is
sca
Ho
wh
su
gi
cl
who
die
in
surf
wa
and
The
intert
biom
is
mad
up
Flow
Oce
Eco
Upw
flow
or
"up
of
FIG
814
Inte
bio
Ro
int
bi
on
th
A
co
and
today
some
majo
legal
coni:I:II
'.~~'"
182
are floating algae, referred
to as
phytoplankton,
Along shores and
ering plants, such as water lilies,
Animal life is often abundant
invertebrate
animals
(collectively
called zooplankton)-both
herbivores and carnivores. Many
species of finfish and shellfish
are found,
flicts continue about access to intertidal areas and harvesting of biological resources.
oceans.
These
productivity
portant in the biosphere
transporters
of materials
as major
from
vast areas
be low in nitrogen
and
tend
America, West Africa, and near
the Arctic and Antartic ice sheets,
to
and phospho-
low
diversity
nutrients
Benthos
("deeps")
is the bottom
portion of oceans.
Primary input
of food is dead organic matter
that falls from above; the waters
are too dark for photosynthesis,
so no plants
grow
there.
Upwellings
are
among
the
ocean
waters
are cold,
Hydrothermal
This
recently
Vents
discovered
biome
(see Chapter 4) occurs in deep
ocean, where plate tectonic
processes create vents of hot
water with a high concentration
of sulfur compounds. These sulfur
compounds provide an energy
basis for chemosynthetic bacteria,
fish.
these waters are nutrient rich because of numerous creatures
Intertidal
of areas exposed alternately to air
during low tide and ocean waters
during high tide (Figure B14).
Constant movement of waters
sink.
(See
North
America.
Chapter
8
worms,
and other
unusual
usually abundant and form a
major part of economic resources.
Near-shore areas are often important breeding grounds for many
species of fish and shellfish, often
of economic
significance.
This
near-shore
part of the oceanic environment
is most susceptible
to
pollution from land sources; as a
major recreational
area, it is subject to considerable
alteration
by
people. Some of the oldest enviconcern the rights
of this biome,
life-
forms. (See Chapter 8.) Water
pressure is high, and temperatures range from boiling point in
waters of vents to the frigid
(about 4°C) waters of deep ocean.
~
transports nutrients into and out
of these areas, which are usually
rich in life and are major economic resources. Large algae are
found here, from giant kelp of
temperate and cold waters to
algae of coral reefs in the tropics.
Attached shellfish and birds are
ronmentallaws
to use resources
zones
Benthos
Deep
significant
welling
most important regions for the
production of commercial fish.
and usually support an
commercially
brought
to the surface by winds
that push coastal waters away
of
algae. Many species of large ani-
land to ocean. Fresh waters are
economically important to people
for their drinking water, production of energy, fish, bird life, and
for recreation and transportation.
Estuaries-areas
at mouths
of rivers where river water mixes
with ocean waters-are
rich in
deep ocean waters brings nutrients to the surface, allowing
abundant
growth of algae and
animals that depend
on algae.
Upwellings
occur off the west
coast of North America, South
Called the pelagic region, the
open ocean biome includes
"Energy
.-
OpenOcean
t