Chapter 34: An Introduction to
Earth’s Diverse Environments
Factors that influence environments
• Abiotic: non living
factors/ examples:
water, air, rocks,
weather
• Biotic: living factors/
examples: animals,
grass, trees
Organization of ecosystem
• Organism 
population
community
ecosystem 
landscapes (an array of
ecosystems)
Environmental problems
• Overgrazing,
deforestation,
overcultivation of land
have caused soil erosion
• Manmade products get
into runoff  soil 
water supply
• Pesticides and DDT
sprayed on crops
Physical and chemical factors that
influence life in the biosphere
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Energy
Temperature
Nutrients
Aquatic factors
Terrestrial factors
Energy source
• Plants: sunlight
• Aquatic plants: sunlight
at the surface
• Dark environments:
inorganic chemicals
• Example: tube wormshas bacteria living in it
that use sulfide to
produce energy
Temperature
• Has a large effect on
metabolism
• Most organisms
perform metabolism
only at certain temps
• Snowy owl: can remain
considerably warmer
than its surroundings so
can be active at a wider
range of temps
Nutrients
• The distribution and abundance of
photosynthetic organisms depend on the
availability of inorganic nutrients
• Soil structure, pH and nutrient content also
effect the ecosystem
Other aquatic factors
• Must depend on oxygen
from water
• Trout: require high
levels of oxygen, cold
and fast moving water
has a higher oxygen
content
• Salinity
• Current
• tides
Other terrestrial factors
• Wind: increases an
organism’s rate of water
loss by evaporation so it
results in the increase
of evaporative cooling
• fire
Regional climate influences the
distribution of terrestrial communities
• Due to the Earth’s
curvature there is an
uneven distribution of
solar energy
• The sun’s rays strike the
equatorial areas most
directly
• Any particular area of
land or ocean near the
equator absorbs more
heat than areas in the
more northern or
southern lattitudes
Seasons
• The northern hemisphere
is tilted most towards the
sun in June so long days
of summer in that
hemisphere and in the
southern hemisphere
short days
• Tropics: the region
surrounding the equator
and has the least seasonal
variation in solar
radiation
How uneven heating causes rain and
wind
• High temps in the tropics evaporate water
from Earth’s surface. Heated by direct rays of
the sun, moist air at the equator rises creating
an area of calm or very light winds known as
doldrums
• As warm air rises, it cools and release much of
its water content creating the abundant
precipitation of most tropical regions
Trade winds
• After losing moisture, high altitude air masses
spread away from the equator until they cool
• The descending dry air absorbs moisture from
the land
• As dry air descends some spreads back to the
equator causing trade winds
Prevailing winds
• Result from the
combined effects of the
rising and falling of air
masses
• Slower moving surfaces
produces westerlies
wind that blows from
the west to the east
Ocean currents
• Unequal heating of
surface waters and the
location and shapes of
the continents creates
ocean currents
• Gulf stream circulates
warm water northward
from the Gulf of Mexico
and makes the climate on
the west coast of Great
Britain warmer during
winter than that coast of
New England
Mountains
• Air temperature
declines by about 6C
with every 1000-m
increase in elevation
• Biomes: types of
ecological associations
that occupy broad
geographic regions of
land or water
Aquatic biomes
• Pelagic realm: all open
water and seafloor (benthic
realm)
• Photic zone: depth of light
penetration
• Continental shelves: shallow
areas
• Aphotic zone: below photic
zone 200 m to 1000m/
sometimes called the
twilight zone
• Intertidal zone: where the
ocan meets land
Plankton
• Phytoplankton:
photosynthesis done by
algae and cyanobacteria
• Zooplankton: small
drifting animals
Coral reefs
• In the photic zone of
warm tropical waters
above continental
shelves
• Built up slowly by
successive generations
of coral animals and
multicellular algae
• Support a huge variety
of invertebrates and
fishes
estuary
• Occurs where a
freshwater stream or
river merges with the
ocean
• Among the most
productive biome on
Earth
• Crucial nesting and
feeding areas for
waterfowl
• Many fishes, crabs and
oyster feed and breed
here
Wetlands
• Transitional between an
aquatic and terrestrial
biome
• Covered with water either
permanently or
temporarily
• Supports the growth of
aquatic plant growth
• Mudflats and salt
marshes often border
wetlands
Freshwater biomes
• Lakes, ponds, rivers,
streams and varieties of
wetlands
• Light, temperature,
nitrogen, phosphorous
all affect these biomes
Terrestrial Biomes
Tropical forests
• Occur in equatorial areas
where the temperature is
warm and the days are
11-12 hours long year
round
• Scarce Rainfall (or a
prolonged dry season)
tropical dry forest prevail
and find a mixture of
thorny shrubs and
deciduous trees and
succulents
Tropical rain forest
• Rainfall is abundant
• Up to 300 species of trees
• Distinct layers: emergent trees
grow above a closed upper
canopy, one or tow layers of
lower trees, a shrub understory
and a sparse ground layer
• Little sunlight reaches the ground
• Many animals dwell in treesmonkeys, birds, insects, snakes,
bats and frogs
• Poor soil, high temps and rainfall
lead to rapid decomposition
Savannas
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Dominated by grasses and scattered
trees
Warm temps year round
30-50 cm rainfall per yr.
Poor soils and lack of moisture lead
to little trees
Grazing animals and frequent fires
caused by lightning inhibit trees
Grasses and forbs grow rapidly during
rainy season providing a good food
source for many animal species
Dominant herbivores are insects
especially ants and termites
Common: mice, moles, gophers,
snakes, ground squirrels, worms and
arthropods
African savannas: giraffes, zebras,
antelopes, lions and cheetahs
Deserts
• Driest of all terrestrial
biomes
• Low and unpredictable
rain fall
• Large deserts in central
Australia and northern
Africa
• Some are very hot and
others are relatively
cold
Deserts continued
• Cycles of growth and
reproduction in the
desert are keyed to
rainfall
• Driest: no perennial
vegetation
• Leaves of some plants
have a waxy coating to
prevent water loss
Deserts
• Desert animals are
adapted to drought and
extreme temps.
• Ants, many birds,
rodents, lizards, snakes,
hawks
Chaparral
• Dense, spiny shrubs
with tough evergreen
leaves
• Mild rainy winters and
hot dry summers
• Perennial shrubs
• Deer, fruit eating birds
and seed eating rodents
like lizards and snakes
Temperate grasslands
• Mostly treeless except
along rivers or streams
• Relatively cold winter temps
• 25-75 cm rainfall/year
• Large grazing animals: bison
and pronghorn of North
America and wild horses
and sheep of Asia
• Birds nests on ground and
some small mammals dig
burrows to escape
predators
Temperate broadleaf forests
• Sufficient moisture to
support the growth of large
trees
• Include most of the eastern
US, most of central Europe
and parts of eastern Asia
and Australia
• Deciduous trees: oak,
hickory, birch, beech maple
• High annual precipitation
• Invertebrates, mice, shrews,
squirrels, bobcats, foxes,
black bears, mountain lions
Coniferous forests
• Cone bearing evergreen
trees like spruce, pine, fir
and hemlock
• AKA tiaga
• Larges terrestrial biome
on Earth
• Long, cold winters and
short, wet summers
• Soil is thin and acidic
• Moose, elk, hares, bears,
wolves, grouse, and
migratory birds
Tundra
• Arctic tundra encircles
the North Pole
• Extremely cold with
little light
• Permafrost: continually
frozen subsoil
• Musk, oxen, caribou,
lemmings, arctic fox,
snowy owl
Water Cycle