1. Title Page Photo
“In short, the animal and vegetable lines,
diverging widely above, join below in a loop.”
loop.”
—Asa Gray (Brainyquote.com)
Ecosystems and Biomes
• Two organizing principles
are ecosystem and biome.
• Ecosystem: A Concept for
All Scales
– Ecosystem —the totality of
interactions among organisms
and the environment in the
area of consideration.
• Encompasses both the living
and nonliving portion and how
energy flows among them.
• Weakness—there is an
almost infinite variety in the
magnitude of ecosystems that
can be studied:
– Range includes whole
Earth itself to drop of water.
Ecosystems and Biomes
• Biome: A Scale for All
Biogeographers
– Biome—a large,
recognizable
assemblage of plants
and animals in
functional interaction
with its environment.
– Most appropriate scale
for understanding
world distribution
patterns.
1

2. Ecosystems and Biomes
• Eleven major types
– Often significant and even
predictable relationships
exist between the biota
(particularly the flora) of a
biome and the associated
climate and soil types.
• Ecotone—the transition
zone between biotic
communities in which the
typical species of one
community intermingle or
interdigitate with those of
Marsh/mangrove ecotone with fire, freeze,
another. and hurricane damage. Taken September
20, 2001
Terrestrial Flora
• Geographers interested in
natural vegetation of
landscape for three
reasons:
1. Plants are likely to dominate
a landscape (except where
terrain is rugged, climate is
harsh, or humans have
intervened);
2. Vegetation is a sensitive
indicator of other
environmental attributes;
3. Vegetation is often
instrumental to human
settlement and activities.
Characteristics of Plants
• Most very hardy.
• High survival potential
dependent on:
– Subsurface root system
– Reproductive mechanism
• Perennial—plant that can
live more than a single
year despite seasonal
climatic variations.
• Annual—plant that
perishes during times of
climatic stress but leaves
behind a reservoir of seeds
to germinate during the
next favorable period.
2

3. Characteristics of Plants
• Common
characteristics:
– Roots (to gather
nutrients and moisture
and to anchor plant);
– Stems and branches
(to support and
transport nutrients);
– Leaves (to collect solar
energy, exchange
gases, and transpire
water);
– Reproductive organs.
Floristic Terminology
• Categorizing by
reproduction:
– Through spores
Spores
• Those that reproduce by
spores are in two major
groups:
– Bryophytes—spore-
bearing plants such as
mosses and liverworts;
never dominated in
history, but can be very
Bryophytes
important in some
localized situations.
– Pteridophytes—spore-
bearing plants such as
ferns, horsetails, and
clubmosses; used to
dominate continental
vegetation, but no more.
Pteridophytes
Floristic Terminology
– Through seeds Seeds
• Those that reproduce by
seeds are in two major
groups: Gymnosperms
– Gymnosperms—seed-
reproducing plants that carry
their seeds in cones; also Angiosperms
known as conifers.
» Used to be more
important, in geologic
past.
– Angiosperms—plants that
have seeds encased in
some sort of protective
body, such as a fruit, a nut,
or a seedpod.
» Have dominated
planet vegetation for
last 50 million to 60
million years.
3

4. – Other terms
Trees
Gymnosperms
Softwood
Coniferous
Needleleaf
Angiosperms
Hardwood
Deciduous
Broadleaf
– Fig. 11-3
Floristic Terminology
• Categorizing by stem or trunk
composition:
– Woody plant—plant that has stem
composed of hard fibrous material;
refers mostly to trees and shrubs.
– Herbaceous—refers to plants that
have soft stems; mostly grasses,
forbs, and lichens.
• Categorizing by leaf retention:
– Deciduous—refers to trees that
experience an annual period in
which all leaves die and usually fall
from the tree, due either to a cold or
dry season.
– Evergreen—a tree or shrub that
sheds its leaves on a sporadic or
successive basis, but at any given
time appears to be fully leaved.
Floristic Terminology
• Categorizing by leaf
shape:
– Broadleaf—tree that has
flat and expansive leaves.
• Majority are deciduous.
• In rainy tropics, everything
is evergreen.
– Needleleaf—refers to trees
adorned with thin slivers of
tough, leathery, waxy
needles rather than typical
leaves.
• Almost all are evergreen.
4

5. Floristic Terminology
• Categorizing by
supposed structure—but
this is unsatisfactory.
– Hardwood—angiosperm
tree that is usually broad-
leaved and deciduous.
Wood has a relatively
complicated structure, but
is not always hard.
– Softwood —gymnosperm
tree; nearly all such trees
are needle-leaved
evergreens with wood of
simple cellular structure but
not always soft.
Environmental Adaptations
• Two prominent adaptation strategies of
plants to protect against environmental
stress are
– Xerophytic adaptations
– Hygrophytic adaptations
Environmental Adaptations
• Xerophytic—refers to
plants structurally
adapting to withstand
protracted dry
conditions.
– Roots, stems, leaves,
reproductive cycle can
all adapt in various
ways.
• Succulent—plant that
has fleshy stem that
stores water.
5

6. Environmental Adaptations
• Hygrophytic—refers to
plants structurally
adapting to withstand
protracted wet
conditions.
• Hygrophytic
Adapatation
– Hygrophyte—plant that
requires a saturated or
semi-saturated
environment (frequent
soakings with water).
Environmental Adaptations
• Likely to have extensive root
system for anchoring in soft
ground.
• Usually relies on buoyancy of
water for support rather than
stem.
• Many have weak, pliable stems
so can withstand currents.
• Hydrophytes are often grouped in
with this category.
– Hydrophyte—a “water-loving” plant
that is adapted to live in more or less
permanently immersed in water.
Environmental Adaptations
• Hygrophytic Adapatation
– Hygrophyte—plant that requires a
saturated or semi-saturated
environment (frequent soakings with
water).
– Likely to have extensive root system
for anchoring in soft ground.
– Usually relies on buoyancy of water
for support rather than stem.
– Many have weak, pliable stems so
can withstand currents.
• Hydrophytes are often grouped in
with this category.
– Hydrophyte—a “water-loving” plant
that is adapted to live in more or less
permanently immersed in water.
6

7. The Critical Role of Competition
• Competition is key
in which plants grow
where.
– Even though all
conditions (climatic,
edaphic, etc.) are
favorable, a plant
Kudzu Vine
may not take hold in
one area because of
competition.
Spatial Groupings of Plants
• Geographers usually
more concerned with
spatial groupings than
individual plants.
– Groups based on
dominant members,
dominant appearance,
or both.
Spatial Groupings of Plants
• Floristic pattern of Earth is
impermanent.
• Change can be slow and
orderly, as in lake infilling.
• Change can be abrupt and
chaotic, as in wildfire.
– Climax vegetation—a stable
plant association of relatively
constant composition that
develops at the end of a long
succession of changes.
7

8. Spatial Groupings of Plants
• Is an association in
equilibrium with prevailing
environmental conditions.
• Should persist until
environmental
disturbance/change
occurs.
• Seral association—various
stages leading up to
climax vegetation.
Spatial Groupings of Plants
• Geographers can face significant difficulties in
recognizing spatial groupings.
• As one tries to identify patterns and recognize
relationships, must make generalizations.
– When associations are portrayed on maps,
boundaries usually represent approximations.
– Human interference plays a major role.
– Because of human impact, climax vegetation is now
the exception rather than rule.
• Maps often ignore human interference, so are
actually maps of theoretical natural vegetation.
Spatial Groupings of Plants
• Many ways to classify
plant associations.
– Geographers usually
place emphasis on
structure and
appearance of
dominant plants.
– Major associations
include forests,
woodlands,
shrublands,
grasslands, deserts,
tundra, and wetlands.
8

9. – Fig. 11-7
Spatial Groupings of Plants
• Forest—an assemblage of trees growing closely together so that
their individual leaf canopies generally overlap.
– Likely to become climax association in any area where moisture is
adequate and growing season isn’t very short.
• Woodland—tree-dominated association in which the trees are
spaced more widely apart than those of forests and do not have
interlacing canopies.
• Shrubland —plant association dominated by relatively short
woody plants.
– Wide latitudinal range but usually restricted to semiarid or arid areas.
Spatial Groupings of Plants
• Grassland—plant association dominated by grasses and forbs.
– Prominent types are savanna, prairie, and steppe.
– Associated with semiarid and subhumid climates.
• Desert—actually a climate, not an association per se, but is typified
by plants widely scattered on bare ground.
• Tundra—a complex mix of very low-growing plants, including
grasses, forbs, dwarf shrubs, mosses, and lichens, but no trees.
– Only in the perennially cold climates of high latitudes or high altitudes.
9

10. Spatial Groupings of Plants
• Wetland—landscape
characterized by
shallow, standing
water all or most of the
year, with vegetation
rising above the water
level.
– Have much more
limited geographic Carson River, NV
extent than any other
above associations.
Spatial Groupings of Plants
• Various plant associations will exist in
relatively narrow zones when mountain
slopes have significant elevational
changes in short horizontal distances.
– Vertical zonation—the horizontal layering
of different plant associations on a
mountainside or hillside.
• Elevation changes are counterpart of
latitude changes.
• Treeline elevation varies with latitude.
• Southern and Northern hemispheres
experience different elevation–latitude
relationship, with Southern Hemisphere
having lower treelines.
• Reason for discrepancy is not understood
yet.
• Can have significant local variations
caused by a variety of local
environmental conditions.
– Vertical Zonation
• Most apparent in mountains due to changes in
elevations over short distances
– Fig. 11-10
10

11. Spatial Groupings of Plants
• Exposure to sunlight is often a critical determinant of
vegetation composition.
– Adret slope—Sun slope; slope where Sun’s rays arrive at a
relatively direct angle.
• Relatively hot and dry, and its vegetation is sparser and smaller
than that on adjacent slopes with different exposures.
• Likely to have species composition different from adjacent slopes.
– Ubac slope—a slope where sunlight strikes at a low angle and
hence is much less effective in heating and evaporating than on
the adret slope, thus producing more luxuriant vegetation of a
richer diversity.
• Difference between adret and ubac decreases with increasing
latitude.
• Valley-bottom locations can have vegetation composition
significantly different from slopes running to it.
– Local Variations
• Exposure to sunlight
– Mountainous landscapes
– Fig. 11-13
– Local Variation (continued)
• Valley-bottom location
– Fig. 11-14
11

12. Spatial Groupings of Plants
• Riparian vegetation—
streamside growth,
particularly prominent
in relatively dry
regions, where stream
courses may be lined
with trees, although no
other trees are to be
found in the
landscape.
Terrestrial Fauna
• Animals occur in much greater
variety than plants over Earth.
• Animals, however, tend to be
much less prominent than plants
in the landscape.
• They tend to be secretive and
inconspicuous.
• Also, environmental relationships
are much less clearly evidenced
by animals than plants.
• Their inconspicuousness makes it
more difficult to study them, and
their mobility had lead to greater
environmental adaptability among
them.
Characteristics of Animals
• Variety of animal life
is so great that it is
difficult to find many
unifying
characteristics.
– Two universal traits
(though these aren’t
always immediately
recognizable):
1. Mobility The tree of life at Animal Kingdom
2. Need to eat plants
and/or other animals
12

13. • Characteristics of Animals
– Great diversity
– Two universal features
• Motile
• Heterotrophs
– Consumers (incapable of manufacturing
food from air, water and sunlight like
plants do)
– Fig. 11-15, 16, 19a, 21, & 27
Kinds of Animals
• Size and habits are not valid indicators of animal’s significance to
geographic study.
• Minute and seemingly inconsequential organisms can play important roles.
• Examples are carriers of disease, providers of scarce nutrients.
• More than 90% of all animal species are invertebrates (without backbones).
• Arthropods most prominent (insects, spiders, centipedes, millipedes,
crustaceans).
• Five groups of vertebrates, those with backbone:
– Fish, amphibians, reptiles, birds, and mammals.
• Kinds of Animals
– Invertebrates
– Vertebrates
• Fishes
• Amphibians
• Reptiles
• Birds
• Mammals
– Fig. 11-15, 16, 19a, 21, 27 & 11-17
13

14. Kinds of Animals
• Most mammals are
placentals, having
young grow and develop
in mother’s body.
– About 135 species are
marsupials, in which
mothers carry young, not
fully developed at birth, in
pouches.
– Two species are
monotremes—lay eggs.
• Echidna and duckbill
platypus.
Environmental Adaptations
• Three different kinds of evolutionary
adaptation by animals:
1. Physiological
2. Behavioral
3. Reproductive
Example of Animal Adaptations to
Desert Life
• Faunal diversity can be
astounding in desert areas
where water is permanent or
prolonged.
• Even in areas where open
water is not available, there
are pockets of localized
favorable habitat that permit
remnant populations to
survive.
• Most animals are completely
nocturnal.
• Animals are more conspicuous
when cooler, such as at night
and winter.
• Some animals follow rains in
nomadic fashion.
• Most prominently displayed by
birds.
14

15. Example of Animal Adaptations to
Desert Life
• Some spend significant time
underground.
• Some bury selves to survive long dry
spells, such as freshwater crayfish and
crabs.
• Text provides detailed discussion of
anatomical and physiological
adaptations.
• A few species of rodents can exist from
birth to death without ever taking a
drink.
• Get moisture from food.
• Some species display ability to delay
reproductive processes over long dry
periods until more favorable conditions
occur.
• Australian desert kangaroos can delay
implantation of fertilized blastocyst, so it
remains in inactive state in uterus until
better weather conditions occur.
Competition Among Animals
• Competition can be
both direct and
indirect.
• Indirect—rivalry for
space and resources.
• Direct—antagonism of
predation.
• Many create social
groups among own
species.
Competition Among Animals
• Some across species, such as
communal relationship among
zebras, wildebeest and impalas in
East African savannas.
• Individual animals are concerned
either largely or entirely with own
survival.
• Some animal species concerned
with survival of mates.
• Some concerned with survival of
young (more common as maternal
instinct, though some paternal too).
• Still fewer concerned with survival
for group.
15

16. Cooperation among Animals
• Symbiosis—association of two
dissimilar organisms, in which
they live together in some
fashion.
• Mutualism—symbiotic
relationship in which the
association is mutually
beneficial to both organisms.
• Commensalism—symbiotic
relationship in which the
association is neither Symbiosis
beneficial nor injurious to
either.
• Parasitism—symbiotic
relationship, in which the
association benefits one, but
harms the other; that is, one
lives on or in the other, to Mutualism Commensalism Parasitism
detriment of the host.
Zoogeographic Regions
• Animals’ distribution
patterns more
complex and irregular
because of their
mobility.
• The broad
distributions of
animals nevertheless
do reflect a general
distribution of energy
and food diversity.
Zoogeographic Regions
• Nine zoogeographic regions are generally
recognized.
• Represent average conditions and cannot
portray some common pattern in which
different groups of animals fit precisely.
• Map on page 329.
16

17.  Zoogeographic Regions
• Reflective of the general distribution of energy
and richness of food chemistry
– Fig. 11-23
Zoogeographic Regions
• Ethiopian Region
– Has most diverse vertebrate
fauna and greatest number
of mammalian families.
• Oriental Region
– Similar to Ethiopian but with
less diversity (save for birds
and reptiles; large number of
venomous snakes).
• Palearctic Region
– Poorer fauna than previous
two;
– Probably function of higher
latitudes and more rigorous
climate.
• Palearctic Region
– Separated from rest of Eurasia by mountains
– Few endemic species, fewer species than in tropics
– Fig. 11-23
17

18. • Nearctic Region
– Non-tropical portions of North America
– Similar to Palearctic due to Bering land bridge
– Fig. 11-23
Zoogeographic Regions
• Nearctic Region
– Faunal assemblage relatively poor (save for
being well-represented with reptiles).
– Largely a transitional zone between
Palearctic and Neotropical groups.
– Great similarity to Palearctic, so that some
group together into superregion, Holoarctic.
– Reflects how faunal dispersal occurred via
Bering land bridge in geologic past.
• Neotropical Region
– Has rich and distinctive faunal assemblage:
– Variety of habitats and isolation from other
regions;
– Has a larger number of endemic mammal
families than any other region;
– Bird fauna is exceedingly diverse and
conspicuous.
Zoogeographic Regions
• Madagascar Region
– Dominated by relic
assemblage of unusual
forms.
– Primitive primates (lemurs).
• New Zealand region
– Fauna dominated by birds
(mostly flightless).
– Almost no terrestrial
vertebrates.
– No mammals and only a
few reptiles and
amphibians.
18

19. Zoogeographic Regions
• Pacific Islands Region
– Limited faunal assemblage.
• Australian Region
– Has most distinctive fauna of any region.
– Lack of variety is made up by animals’ uniqueness.
– The Unique Biota of Australia
– More than 90% of the native tree species in Australia are of the
single genus, Eucalyptus.
• Above should either be “a single genus, Euc” or “the single genus
Euc” (no comma)
– These trees, which there are greater than 400 species of, are
native only to Australia.
– The shrubs and bushes of Australia are dominated by a single
genus, Acacia.
– The dominance of this genus is attributed to isolation.
– Australia Region
• Australia and
adjacent islands
• Most distinctive
fauna of any region
due to the region’s
lengthy isolation
– Few placental
mammals
• Its unique biota are
also primarily a
result of isolation – Fig. 11-17: Kangaroo. Fig. 11-18:
Monotremes (egg-laying mammals)
Echidna and duckbill platypus.
Zoogeographic Regions
• Australian fauna is also unique
because of isolation.
– Australian fauna is dominated by a
single primitive mammalian order,
marsupials.
– The continent is also the only home to
the primitive monotremes.
– Marsupials and monotremes were
able to flourish in relative isolation
from competitive and predatory
pressures that influenced animal
evolution in other parts of the world.
– As such, indigenous placental
mammals are lacking on the
continent.
19

20. The Major Biomes
• Named for dominant vegetation, but
encompasses fauna as well as
interrelationships with soil, climate, and
topography.
 Major Biomes
• Summary of each
biome follows…
– Distribution (map)
– Climate types
– Main vegetation
types
– Limiting factors to
flora and fauna
– Fig. 11-25
(left panel, p. 330)
– Fig. 11-25 (right panel, p. 331)
20

21. The Major Biomes
• Tropical Rainforest
– Selva — tropical rainforest; a
distinctive assemblage of tropical
vegetation that is dominated by a
great variety of tall, high-crowned
trees.
• Probably most complex of all
terrestrial ecosystems.
– Distribution closely related to
climate.
– Consistent rainfall and relatively
high temperatures.
– Layered structure, with second
layer being a branch canopy
formed by the high trees that crest
above the canopy.
– Undergrowth relatively sparse
because of lack of light.
– Interior is region of heavy shade,
high humidity, windless air,
continuous warmth, aroma of
mold and decomposition.
– Fauna is largely arboreal—tree
dwelling.
– Canopy serves as principal food
source.
The Major Biomes
• Tropical Deciduous Forest
– Not closely correlated with
specific climatic types;
distribution more irregular and
fragmented.
– Compared to rainforest,
canopy is less dense, trees
are shorter, and there is less
diversity of tree species (but
greater variety of shrubs and
other lesser plants).
– Response to either less total
precipitation or less periodic
precipitation.
– Many trees shed leaves at
same time, so more sunlight
can penetrate.
– Produces classic jungle
conditions.
The Major Biomes
• Tropical Scrub
– Widespread in drier portions of
A climatic realm (covers
extensive areas in tropics and
subtropics).
– Dominated by low-growing
scraggly trees and tall bushes,
usually with extensive
understory of grasses.
– Plant species diversity less
than that in tropical rainforest
and tropical deciduous.
– Faunal diversity very different
from tropical rainforest and
tropical deciduous.
– Moderately rich assemblage of
ground-dwelling mammals and
reptiles, and of birds and
insects.
21

22. The Major Biomes
• Tropical Savanna
– Distribution of biome doesn’t
exactly correlate with distribution
of tropical savanna climate.
– Incomplete correlation most
noticeable where seasonal rainfall
contrasts are greatest (which is
associated with annual shifting of
the intertropical convergence zone
[ITCZ]).
– Dominated by tall grasses.
– Some regions actually former
tropical deciduous forest and even
tropical rainforest, but humans
converted it through fires and by
grazing domestic animals.
– Has a very pronounced seasonal
rhythm: wet season, dry season,
and wildfire season.
– Savanna fauna varies according
to continent.
– Africa has most remarkable,
diverse large wildlife.
– Latin America has only sparse
population of large wildlife.
The Major Biomes
• Desert
– Occurs extensively in
midlatitude locations in Asia,
North America, and South
America with a fairly close
correlation to Bwh and Bwk
climates.
– Vegetation surprisingly
variable.
– Shrubs are typical, with
succulents common in drier
parts.
– Trees can be found,
particularly in Australia.
– Most deserts have
moderately diverse faunal
assemblage.
– Variety of large mammals is
limited.
The Major Biomes
• Mediterranean Woodland and
Shrub
– Six widely scattered and relatively
small areas in midlatitudes.
– Have pronounced dry-summer
wet-winter precipitation.
– Dominant vegetation associations
are physically similar, but
taxonomically quite varied.
– Dominated by dense growth of
woody shrubs, but also have open
grassy woodlands.
– Plant species vary from region to
region, but in all, the trees and
shrubs are primarily broadleaf
evergreens.
– Many plants are adapted to rapid
recovery after wildfire.
– Fauna not particularly distinctive.
– Seed-eating, burrowing rodents
common.
– General overlap of animals
between this biome and adjacent
ones.
22

23. The Major Biomes
• Midlatitude Grassland
– Locational coincidence between
this biome and steppe climatic
type is very pronounced in
Northern Hemisphere.
– Less distinct climatic correlations
in Southern Hemisphere.
– Occurs widely in midlatitudes of
North America and Eurasia.
– Low precipitation and/or frequency
of fire prevent growth of tree or
shrub seedlings.
– Characteristics of grasses
depends on moisture: taller in
wetter area (prairie), shorter in
dryer (steppe), and sometimes not
continuous, but grow in discrete
tufts.
– Before human encroachment,
fauna comprised of large numbers
of relatively few species, with
migratory larger herbivores.
The Major Biomes
• Midlatitude Deciduous Forest
– Used to be far more extensive
in all Northern Hemisphere
continents and to some extent
in tracts in Southern
Hemisphere.
– Humans have cleared away
large portions for agriculture.
– Fairly dense growth of tall
broadleaf trees with complete
canopy in summer.
– Winter very different, with
seasonal fall of leaves.
– Tree species vary greatly from
region to region.
– Generally has the richest
assemblage of fauna in
midlatitudes.
– Seasonal variation to fauna
(hibernation and migration).
The Major Biomes
• Boreal Forest
– An extensive needleleaf forest in subarctic
regions of North America and Eurasia; also
called taiga.
– One of most extensive biomes, occupying
vast expanse of northern North America and
Eurasia.
– Close correlation with subarctic climatic type.
– Has perhaps simplest assemblage of plants.
– Most trees are conifers, though in some
places deciduous trees interrupt the
coniferous cover.
– Trees become spindlier, short, and openly
spaced in north.
– Bogs and swamps numerous because of
permanently frozen subsoil and derangement
of normal surface drainage from past
glaciers.
– Faunal diversity limited because of limited
food supply.
– Populations of some species can fluctuate
enormously in space of year or so.
– Insects absent in winter but superabundant in
brief summer.
23

24. The Major Biomes
• Tundra
– Distribution along northern
edge of Northern
Hemisphere continents.
– Essentially a cold desert or
grassland.
– No trees, but considerable
mixture of species
(grasses, mosses, lichens,
flowering herbs, and a
scattering of low shrubs).
– Dominant animal life
consists of bird and insects
during summer.
– Few species of mammals
and freshwater fishes and
almost no reptiles or
amphibians.
The Major Biomes
• Alpine Tundra
– Found in many
high-elevation
regions.
– Above timberline
there is sparse
vegetation cover,
consisting mostly of
herbaceous plants,
grasses, and low
shrubs.
Human Modification of Natural
Distribution Patterns
• Human activities severely alter natural
distribution patterns of biota.
• Humans directly influence biotic
distributions in three ways:
1. Physical removal of organisms
2. Habitat modification
3. Artificial translocation of organisms
24

25. Physical Removal of Organisms
• Humans severely
modify landscape,
affecting both plants
and animal
inhabitants.
• Cut down, plow up,
pave over, burn out,
– Fig. 11-41. Central
America – one of highest
poison, shoot, trap,
rates of deforestation otherwise eradicate.
(due mainly to
expansion of cattle
ranching)
Habitat Modification
• Humans affect native
plants and animals by
changing their habitat.
• Humans change soil
environment through
farming, grazing,
engineering, and
construction.
• Humans degrade
atmospheric environment
through pollution.
• Humans impound, divert,
• Removal for agriculture often
and pollute waters.
• results in soil erosion and
• low crop yields as well as
• wildlife habitat destruction.
Tropical Rainforest Removal
• One of Earth’s most serious environmental problems, as
of last decade or so.
• Rate of deforestation = 51 acres (21 hectares) per
minute.
• More than half of original African rainforest is now gone,
about 45% of Asia’s and close to 40% of Latin
America’s.
• Current situation varies in five major rainforest regions.
• In mid-1980s, extinction rates = about 1 species per day.
• In mid 1990s, extinction rates = about 2 species per
hour.
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26. Tropical Rainforest Removal
• Loss of forest also contributes to:
– Accelerated soil erosion
– Drought
– Flooding
– Water-quality degradation
– Declining agricultural productivity
– Greater poverty for rural inhabitants
– Increasing atmospheric carbon dioxide (greenhouse
effect).
– Anticipated economic benefits are usually illusory.
Tropical Rainforest Removal
• Continuous heavy (and expensive) fertilization necessary for
sustainable agriculture.
• Losing potential valuable resources—pharmaceutical products, new
food crops, natural insecticides, industrial material, and crop
hybridizations (for resisting disease, insects, parasites, and other
environmental stresses).
• Development of agroforestry (the planting of crops with trees) to
counteract some of the destruction.
• UNESCO project to set aside reserves to protect biodiversity.
• At present about 300 preserves have been established in more than
75 countries, encompassing 12 million hectares.
• Artificial Translocation of Organisms
Tropical Rainforest Removal
• Humans have introduced many
wild plants and animals into
“new” habitats.
• Exotic species—organism that
is introduced into “new” habitats
in which it did not naturally
occur.
• Sometimes deliberate,
sometimes accidental.
• Exotics have had great impacts
(cats on flightless bird
populations in New Zealand,
European flea in all parts of Walking Catfish, Florida
world).
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27. Biotic Rearrangement: The Sad
Case of Florida
• Human actions in introducing exotic
(nonnative) species result in usually one of
two extremes:
• Either exotic dies out in a short time; or
• It flourishes extraordinarily.
• When flourishes, can occasionally have a
salutary effect, but many cases either
unsatisfactory or absolutely disastrous.
Biotic Rearrangement: The Sad
Case of Florida
• Florida presents perhaps the most frightening case
study.
• In last decade or so, state has experienced one of
highest in-migration of people anywhere.
• Has created massive disruptions in ecosystems, and
exotics are most likely to prosper when ecosystem is
unstable.
• Artificial drainage provides routes for easy dispersal of
aquatic organisms.
• Has become the major world center for animal-import
industry.
• Has become almost as important in plant import industry.
• Inevitable that many escape (some are turned loose).
Biotic Rearrangement: The Sad
Case of Florida
• Dozens of species of exotic plants
have become widespread, and
most are expanding their ranges.
• Spread of melaleuca tree has
changed swamps to forests.
• Aquatic weeds infest more than half
a million acres of waters.
• Many exotic animal species well
established and some spreading
rapidly.
• Exotic fish more numerous and
pose even more serious problems,
competing with native species.
• Greatest present and potential Salt Cedars
threat is so-called walking catfish
from Southeast Asia.
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28. Focus: Desert Adaptations of the
Amazing Camel
• Dromedary (one-humped) camel has developed
the most remarkable series of adjustments to
desert environment.
• Anatomical adaptations include
• Light-colored and shiny summer coat reflects hot
sunlight.
• Deeply cleft upper lip allows moisture loss from
nose to be recycled back into mouth.
• Nostrils are horizontal slits that keep sand and
dust out.
Focus: Desert Adaptations of the
Amazing Camel
• Eyes set beneath shaggy brows for shade, and double
eyelids to protect eyes from sand.
• Broad and elastic feet for good traction and protection
against the hot sand.
• Physiological adaptations include
• Highly fluctuating body temperatures that allow them to
conserve moisture through minimal perspiration.
• Little production of urine and little moisture voided in
their feces.
• Can stand long periods without water and can rapidly
rehydrate when drinking.
• They cannot, however, store moisture in their hump.
People and the Environment:
Rainforest Loss in Brazil
• Brazil contains about one-third of the planet’s tropical rainforest.
• Settlement over the last 50 years in the forest has led to large tracts
of it being cleared for settlement and logging.
• This clearing has been facilitated by the construction of the Cuiabá-
Port Velho highway.
• By the late 1980s deforestation had increased substantially, and by
2001 the amount removed was extraordinary.
• In 2004, more than 26,000 square kilometers of rainforest were lost.
• Much of the land is cleared for grazing land, which is then
abandoned after a couple of years due to the poor fertility of tropical
soils.
• This is leading to habitat and species loss in the region.
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