Kinds of
Ecosystems
Chapter 4
“In all things of nature there is something of the marvelous.”
Aristotle, Greek Philosopher
Biomes of the World
• Earth is covered by hundreds of types of
ecosystems which are grouped into a few
biomes
• Biomes have distinctive climates, plants
and organisms; they are named for their
plant life but the main determinant is the
climate (temperature, precipitation,
humidity, winds)
4.1 Forests
Tropical Rainforests
• Occur in a belt around the Earth near the equator
• Always humid and warm; get about 250 cm (100 in)
of rain per year
• Get strong sunlight year-round; maintains a climate
with little seasonal variation in temperature.
• Ideal climate for growing plants; nourishes more plant
species than any other biome (1 hectare temperate
forest contains 10 species of trees/ same area of
tropical rainforest contain over 100 species)
• Soil is not rich, usually thin and poor; rapid decay of
plants and animals return nutrients to soil---used up
by plants or washed away by rainfall
• Trees form aboveground roots—growing sideways
from the trees, providing extra support
Rainforest: Plant Adaptations
• Plants grow in layers; trees more than 30 m
(100 ft) tall form a dense canopy-absorbs at
least 95% of the sunlight
• Little light reaches below the canopy
(understory); only trees and shrubs adapted
to shade can grow (ex: herbs with large flat
leaves)
• When trees fall, tree seedlings adapted to
grow quickly outcompete other seedlings
• Orchids and monkey ladder vines use the
tall tree trunks for support high in the canopy
Rainforest: Animal Adaptations
• Incredible diversity of vegetation may have led to
the evolution of the greatest diversity of animals
anywhere on Earth
• Little competition; most animals are specialists and
are adapted for a specific purpose
ex: antwrens – variety of species that eat insects at
different layers; flowering plants that can be pollinated by only
one species of insect, bat or bird
• Some animals have developed elaborate methods
for escaping predators; others have equally
evolved methods of capturing their prey
ex: insects (butterfly) that looks like a leaf or twig; frogs
that blend perfectly with plants; poisons on their skin with
bright colors to warn predators
Threats to Rainforests
• Used to cover 20% of Earth’s surface; today,
only about 7%
• Every year tropical rainforests are stripped by
logging operations or cleared for farming or
cattle grazing (the size of North and South
Carolina combined)
• As they disappear, so do the habitats, plants
and animals become extinct
• Traditions and cultures are lost as native people
are displaced
• Help save the rainforests by looking for rainforest friendly products and support
organizations that preserve tropical forests
Temperate Rain Forest
• Found in North and South America, Australia and
New Zealand
• Pacific Northwest is home of the only North
American temperate rainforest
• 300 ft tall evergreen trees (Sitka spruce, Douglas
fir) dominate the forest; mosses, lichens and ferns
are abundant
• Moisture pervades everything; cool, humid forest
• Located at 48° north latitude; rarely freezes (Pacific
Ocean moderates the temperature)
Temperate Deciduous Forests
• Occur between 30° and 50° north latitude;
seasonal variations can be extreme and growing
season is from 4 to 6 months
• Trees drop their leaves in the fall; summer
temperatures can soar to 35° C ( 95° F); winter
temperatures plummet below freezing
• Deciduous forests are moist receiving 75-250 cm
(30-100 in) of precipitation
• Rain and snow help decompose dead organic
matter (leaves) contributing to the deep, rich soil
Deciduous Forests: Plant Adaptations
• Plants grow in layers; forest canopy is dominated
by tall trees (maple, oak, birch)
• Small trees, shrubs, bushes grow in the understory
• Forest floor gets more light than the rain forest
floor, thus more ferns, herbs and mosses grow
there
• Plants are adapted to survive seasonal changes;
seeds, bulbs and rhizomes become dormant in the
ground, trees lose their leaves
• In spring, as sunlight increases and temperatures
increase, leaves re-emerge on trees, seeds
germinate and rhizomes and roots put forth new
shoots
Deciduous Forests: Animal Adaptations
• Animals are adapted to forage the forest
plants for food and shelter
• Squirrels eat nuts, seeds and fruits; bears
eat leaves and berries, deer eat leaves from
trees and shrubs; birds nest in the tops of
trees
• Birds are migratory—fly south in the winter
to avoid the harsh weather; return in spring
• Animals that stay use various strategies for
survival—bears and squirrels become
inactive; insects enter a state of very low
metabolic activity
Taiga
• Aka: boreal forest; has rough terrain and the
forest floor is sparsely vegetated
• Trees seem barren until you look up to see the
green tops
• Located across the northern hemisphere just
below the Arctic Circle; winters are 6 to 10
months and extremely cold with subfreezing
temperatures that plummet to -20°C (-4°F).
• The frost-free growing season may be as short
as 50 days depending on the latitude;
enhanced only by constant daylight during the
summer months
Taiga: Plant Adaptations
• Trees whose seeds develop cones (conifers, such
as, pine, hemlock, fir, spruce) do not shed their
needle-shaped leaves; narrow shape leaves and
waxy coating retain water when moisture in the
ground in frozen
• The shape (pointed) of the tree helps it shed snow;
otherwise the snow would crush the tree
• Conifer needles (contain acidic substances), acidify
the soil when they fall, preventing other plants from
growing; blueberries, a few ferns and mosses can
survive the acidic soil
• Climate and acidity hinder decomposition which
results in slow soil formation
Taiga: Animal Adaptations
• This biome is dotted with lakes and
swamps in the summer, attracting birds
that feed on insects, fish or other wetland
organisms
• Birds migrate south in the winter; shrews
and voles burrow underground; moose
and arctic hare eat whatever vegetation
they can find; lynx, wolves and foxes eat
the hare and shed their brown summer fur
and re-grow a thick white fur in the winter
4.2: Grasslands, Chaparral, Deserts and Tundra
• Climates with less rainfall:
forests  savannas, grasslands, chaparrals  deserts
• As precipitation decreases, so does the
diversity of species present
• Number of different species is smaller,
individuals of each species is even smaller
• Another type of “desert” is present far to
the north. It is called the tundra. Very little
precipitation occurs here and temperatures
stay very cold year round
Savannas
• West African plains contain the greatest
collection of grazing animals on Earth and
the predators that hunt them
• Found near the tropics, near the equator
• Not many trees, too little rainfall (only at
certain times of the year)
• Grass fires may sweep across savannas in
the dry season
Savannas: Animal Adaptations
• Migratory lifestyle of the large, grazing
herbivores.
• Animals follow the rains to newly sprouted
grasses
• Predatory animals follow their mobile food
source
• Give birth during rainy season when food
is more abundant and survival is greatest
• Avoid competition by eating vegetation at
different heights
Savannas: Plant Adaptations
• Savanna trees and grasses have large
underground root systems that survive
fires so plants regrow quickly after fires
and survive long dry seasons
• Course savanna grasses have vertical
leaves
• Trees and shrubs have thorns or razor
sharp leaves – deter herbivores
Temperate Grasslands: Prairies, Steppes and Pampas
• Grasslands have the most fertile soil of any biome
• Many grasslands have been replaced with crops of
corn, soybean and wheat
• Grasslands at one time covered 42% of the total
land surface on Earth; today, they cover only about
12%
• Found on interiors of continents where there is too
little rainfall for trees to grow
• Mountains play a crucial role in maintaining
grasslands by blocking rain clouds thus maintaining
low rainfalls
• Sizzling summer temperatures make grasslands a
tinderbox; fire is common in grasslands
Temperate Grasslands: Plant Adaptations
• Prairie grasses are perennials, surviving
from year to year
• Root systems form dense mats the survive
drought and fire and hold the soil in place
• Rainfall determines what type of grasses
will grow in an area
• Few trees will survive on the grasslands
because of drought, fire and constant
battering of winds
Temperate Grasslands: Animal Adaptations
• Grazing animals (pronghorn antelope and
American Buffalo) have large, flat back
teeth for chewing coarse prairie grasses
• Grazers cope with severe winters by
growing thick coats of fur which they shed
in spring
• Badgers, prairie dogs, owls live in
protected underground burrows; these
burrows shield them from fire, the
elements and predators
Threats to Temperate Grasslands
• Cultivation and overgrazing have changed
the grasslands
• Grain crops have replaced native grasses
and cannot hold the soil in place as well
because their roots are shallow, resulting
in soil erosion
• Overgrazed animals are constantly
chewing down the grasses hindering them
from regenerating or holding the soil, thus
furthering soil erosion
Chaparral
• Occurs in the mid-latitudes (30 degrees
north and south of the equator)
• Lies primarily in coastal areas that have
Mediterranean climates
• Known for their hot, dry summers; mild,
wet winters; and slight variations in
seasonal temperatures
Chaparral: Plant Adaptations
• Mostly low-lying evergreen shrubs and
small trees
ex: chamise, manzanita, shrub oak, olive trees and
cooking herbs like sage and bay
• Plants have small, leathery leaves that
resist water loss; they contain oils that
promote burning
• Natural fires destroy trees allowing light
and space for smaller plants
• Plants are well adapted and can regrow
from small bits of surviving tissue
Chaparral: Animal Adaptations
• Common adaptation is camouflage –
shape or coloring that allows them to blend
with their environment
• Quail, lizards, chipmunks and mule deer
have brownish gray coats that allows them
to move through the brush
• Animals have adapted to seasonal
differences for food
ex: scrub jay (bird) has a beak adapted for a
varied diet (insects, seeds, other birds’ eggs
and baby birds)
Threats to the Chaparral
• Biggest threat worldwide is human
development
• This biome has lots of sun, access to
oceans and mild year-round climates
which is inviting to humans
Deserts
• They are the driest places on Earth,
receiving less than 25 cm (10 in) of
precipitation a year
• Hot deserts occur closer to the equator
than cold deserts
• Often occur in the rain shadow of
mountains (leeward side of the mountain)
Deserts: Plant Adaptations
• Plants in the desert have adaptations for
obtaining and conserving water
• Succulents and cacti have thick, fleshy stems
and leaves that store water; have waxy
coating to prevent water loss
• Spines deter thirsty animals from eating plant’s
juicy flesh
• Roots are shallow and spread out widely
• Plants are adapted to drought, will die when it
is too dry, drop their seeds which lie dormant
until the next rainfall when they germinate,
grow and bloom before the soil becomes dry
again (drought-resistance)
Deserts: Animal Adaptations
• Reptiles (gila monsters, rattlesnakes) have
thick, scaly skins that prevent water loss
• Amphibians (spadefoot toad) survive
scorching desert summers by burying
themselves in the ground and sleeping
through the dry season (estivating)
• Insects and spiders are covered with body
armor to help them retain water
• Most animals are activate at night or at
dusk, when the air is cooler
Threats to the Desert
• In the American West, residential
development encroaches upon the desert
areas
• Off-road and all-terrain vehicles kill desert
vegetation, destroying habitats of
endangered animals (desert tortoise)
• Humans removing desert plants endanger
plant populations
Tundra
• Lies north of the Arctic Circle; has no tall
trees
• Frozen soil supports mostly tough grasses
and shrubs
• Summers are short; only a few inches of
the soil thaws; becomes dotted with bogs
and swamps during the thaw periods;
makes an ideal breeding ground for huge
numbers of swarming insects (mosquitoes,
blackflies) and birds that feed on them
• Under soil lies the permafrost
(permanently frozen soil)
Tundra: Plant Adaptations
• Mosses and lichens cover acres of rocks
(don’t need soil to grow)
• Where soil (thin) exists, plants have shallow,
wide roots which anchor them against arctic
winds
• Flowering plants (moss campion, gentian) are
tiny and hug the ground for warmth and to stay
out of the wind
• Woody plants and perennials (willow, junipers)
have evolved dwarf forms and grow flat or
trailing
• Plants grow and flower quickly (short
summers)
Tundra: Animal Adaptations
• Millions of migratory birds breed during the
short summer because of the abundant
food supply (plants, mollusks, worms,
insects)
• Caribou and reindeer migrate; wolves prey
on the caribou, deer, moose, lemmings,
mice and rabbits.
• Rodents burrow underground during
winter
• Year-round residents (arctic fox) have
white fur in winter; coats are extremely
well insulated (musk ox)
Threats to the Tundra
• One of the most fragile biomes on Earth
• Food chains are relatively simple and can
be disrupted easily
• Conditions are so extreme, land is easily
damaged and slow to recover.
• Oil extraction and transport across land
has brought humans to the area, which
has disturbed the delicate balance of the
biome
4.3 Freshwater Ecosystems
• Includes sluggish waters of lakes and
ponds, moving waters of rivers and
streams and areas where land and water
come together
• Contains relatively little dissolved salt
• Plant and animal life depends on depth of
water; how fast water moves; amount of
sunlight, mineral nutrients, oxygen
Lakes and Ponds
• Littoral zone – where aquatic life close to shore is
diverse and abundant; nutrient-rich area
• Further out, where there is still sunlight for
photosynthesis, live the phytoplankton (plants) and
zooplankton (tiny animals)
• Deep lakes and ponds (too little light) contain a few fish
adapted to cooler water and bacteria (decompose the
dead plants and animals)
• Benthic Zone – bottom of a body of water; inhabited
by decomposers, insect larvae, clams
• Lakes with large amounts of plant matter are
eutrophic (plants and algae grow in large quantities;
bacteria break down dead matter using up oxygen;
diversity of species decline).
Lakes and Ponds: Plant and Animal Adaptations
• Along the shore (cattail, reeds) are rooted in
the bottom mud, leaves emerge above water
• Deep water contain floating plants (pond lilies)
• Water beetles use hairs under their bodies to
trap surface air to breathe during dives for food
• Catfish sense with whiskers
• Fish are adapted to certain temperature
ranges: lake trout (cold water); bass (warmer
waters)
• Amphibians will burrow in mud in lakes that
partially freeze
Wetlands
• Areas that are covered by water for at least part of
the year
• Two main types:
Marshes: contain non-woody plants
Swamps: contain woody plants or shrubs
• Perform several important environmental functions:
serve as spawning and feeding grounds for game
fish; providing homes for native and migratory
wildlife (including endangered and threatened
species); vegetation traps carbon which would
otherwise be released back into the atmosphere as
carbon dioxide; removes pollutants from water;
controls flooding; produces products such as
cranberries, blueberries, peat moss
Wetlands: Marshes
• Shallow waters contain reeds, rushes and
cattails; deep waters (benthic) contain plants,
decomposers and scavengers
• Grebe and ducks (waterfowl) have beaks
adapted for eating marsh vegetation
• Herons have spear like beaks to catch small
fish and frogs
• Attract nesting birds (blackbirds)
• Kinds of marshes: (determined by salinity)
Brackish: slight salinity
Tidal: saltier water
• Florida Everglades is largest freshwater marsh in
U.S.
Wetlands: Swamps
• Occur on flat, poorly drained land, near
streams
• Dominated by shrubs or water-tolerant
trees (red maple, cedar, oak, cypress –
depending on latitude and climate)
• Mangrove swamps occur in warm climates
near ocean (more saline water)
• Ideal habitat for amphibians (green frog,
salamanders) and attract birds (wood
ducks) that nest in hollow trees
Threats to Wetlands
• Used to be considered wastelands (breeding
grounds for pesky insects) so people “improve”
them by draining and clearing them for farms,
residential or commercial development
• However, we now view them as purifiers
(wastewater and absorbers of hazardous flood
waters)
• Vital habitats for wildlife for breeding (herons,
storks, other birds)
• Home to many amphibians and reptiles (alligators,
crocodiles)
• Federal government now prohibits the destruction
of wetland areas
Rivers
• Originate from snowmelt in mountains
• Headwaters-water is usually very cold and
highly oxygenated; runs swiftly; shallow
• As it moves down the mountain, it
broadens; water is warmer, loses oxygen
and flows more slowly
• Characteristics vary depending on land
and climate
• Runoff wash nutrients and sediment from
surrounding land into a river, thus affecting
growth and health of organisms in the river
Rivers: Plant and Animal Adaptations
• Near headwaters, mosses anchor themselves to
the rocks
• Mayflies use hooks on their legs to cling to any
stable surface
• Trout (streamlined bodies, powerful swimmers) and
minnows are adapted to live in the cold, highly
oxygenated water
• Downstream – catfish, carp (adapted to glide over
river bottom) prefer warmer, calmer water
• Freshwater aquatic plants (crowfoot) set roots in
soil; many have arrowhead shaped leaves
depending on the speed of the water
Threats to Rivers
• Industries use river water in manufacturing
processes and as a receptacle for waste
• People have used rivers to dump sewage and
garbage
• These practices have polluted the rivers with
toxins; killing river organisms and making the fish
inedible
• Runoff from the land is putting pesticides and other
poisons into the rivers and coats the riverbeds with
toxic sediments
• Dams alter river flows and destroy fish habitats
4.4 Marine Ecosystems
• The oceans of the world contain a wide
variety of plants and animal communities
• The types of organisms present in marine
ecosystems depend on temperature and
the amount of sunlight and nutrients are
available.
Estuaries
• An ecosystem where fresh water from
rivers mixes with the salt water from the
ocean; mineral rich soil; a nutrient trap; in
shallow areas, marsh grass grows
• One week each spring, huge snowshoe
crab crawl out of the ocean onto the
beaches of the Delaware Bay to mate and
lay their eggs. Shorebirds wait for them
and millions of migrating birds will stop
there to gorge on the eggs
Estuaries: Plant and Animal Adaptations
• Among the most productive ecosystems;
contain plenty of light, nutrients for plants
• Rivers supply nutrients washed from the land;
water is shallow; sunlight reaches the bottom
• Can support large amounts of plants,
phytoplankton and zooplankton which provide
food for larger animals (fish, dolphins,
manatees, seals, other mammals)
• Oysters, barnacles, clams live anchored to
marsh grass or on the bottom and filter algae
and debris out of the water
• Organisms can tolerate variations in salinity
Threats to Estuaries
• Many of the world’s major ports are built on
estuaries; seven of the ten largest urban areas
(Tokyo, New York, Shanghai, Calcutta,
Buenos Aires, Rio de Janeiro, Bombay)
• Were used as dumping grounds, especially in
California; now, plans are to restore them to
estuary wetlands
• Industrial waste, agricultural runoff, pesticides,
fertilizers damage estuaries
• Most of the pollutants will break down over
time, but estuaries cannot cope with the large
amounts produced by humans
Coral Reefs
• Limestone islands in the sea that are built
by coral animals called polyps (very slow
growing); thousands of species of plants
and animals live in the cracks and
crevices; among the most diverse
ecosystems on Earth
• Corals live in only warm salt water; a lot of
light for photosynthesis; shallow, tropical
seas
• Only outer layer of coral is living
Coral Reefs: Animal Adaptations
• Coral Polyps are predators that never
chase their prey; use stinging tentacles to
capture small animals that float or swim
too close
• Provide habitats for a variety of tropical
fish, snails, clams, sponges
• Parrotfish have teeth fused into their beaks
which they use to scrape algae and corals
off the reefs to eat
Threats to Coral Reefs
• If they get too hot or too cold, or fresh water drains
into the water surrounding the reef, corals cannot
produce limestone.
• If it is too muddy, too polluted, too high in nutrients,
algae will die or grow out of control and smother
the corals
• Oil spills, sewage, pesticides, silt runoff are linked
to coral-reef destruction
• Overfishing can devastate fish populations,
upsetting the balance
• Reef cannot repair itself after being destroyed by
careless divers, shipwrecks, anchors, people
breaking off pieces
The Ocean
• Covers nearly ¾ of Earth’s surface
• Plants only grow where there are nutrients
and light; most life is in shallow water
around the edges of continents; abundant
with plants and animals in these areas
• Open ocean, phytoplankton grows near
the surface (sunlight) if there are nutrients;
one of the least productive of all
ecosystems
• The depths of the ocean are dark and
most of the food consists of dead
organisms (falling from the surface)
Ocean: Plant Adaptations
• No flowering plants except around the
edges
• Food for herbivores in the open ocean are
phytoplankton (floating by being buoyant
or having long spines; whip-like flagella; oil
droplets)
• When they die, they sink to the bottom
Ocean: Animal Adaptations
• Smallest herbivores are the zooplankton (jellyfish, tiny
shrimp, fish larvae) which live near the surface; others
(oysters, lobsters) live at the bottom
• Dozens of fish, as well as seals and whales (mammals) feed
on plankton
• Evolved sleek, tapered shapes for moving through dense
water; silvery color (protective camouflage); buoyancy
devices to stay at one level (sharks –oily livers; bony fish –
gas-filled swim bladders; mammals – lungs
• Sunlight penetrates about 100 m (330 ft) into the sea; no
light below that (decomposers, filter feeders and organisms
that eat them live here)
• Poor visibility at these depths so organisms use “light” to
communicate (luminous) or sound (whales – “songs”;
dolphins – clicks and calls
Threats to the Ocean
• Pollution – comes from the land; same as the
pollutants on the land (fertilizers causing toxic algal
blooms; industrial waste; sewage discharged into
rivers, particularly from nuclear power plants)
• Overfishing and some fishing methods have
destroyed fishing grounds, nets entangling every
living thing bigger than the holes (most of the catch
are not used and are thrown back, dead); marine
mammals drown; fishing lines are discarded in the
ocean and strangle fish, seal
• All of these things are reducing reproduction thus
endangering many species
Polar Ecosystems
• Ice covered North and South Pole are
considered marine ecosystems because
most of the food supply is phytoplankton
• South Pole lies on the continent of
Antarctica and is covered with a
permanent icecap (melts only around the
edges); North Pole is not on land at all; lies
in the Arctic Ocean, frozen into a huge
iceberg throughout the year with little
icebergs floating around it
The Arctic
• Relatively shallow; rich in nutrients;
supports large populations of plankton
• This provides food for a diversity of fish,
whales, ocean birds (who prey on the fish),
seals
• The birds and seal bear their young on the
ice; they provide food for the few humans
that live there and for the polar bear
The Antarctic
• Only continent never colonized by humans
• Used mainly for research on the unusual
animals that live there
• Only a few plants live there
• Plankton forms basis of the food chain;
feeds fish, whales, penguins
Threats to Polar Ecosystems
• Contains reserves of minerals (oil) whose
extraction would disrupt this large
untouched ecosystem
• Conservationists want it made into a world
wildlife refuge
• Main threat is tourism (garbage left behind,
does not decay because it is so cold)
• They are working to solve that problem