Ch. 6 Earth’s Ecosystem
Lesson 1 – Main Idea: Any place that life
exists & interacts with its environment is
an ecosystem. Forests, deserts,
grasslands, & oceans are some
ecosystems.
Community Interactions
Living things depends on one another & on
nonliving things such as air, water, & soil.
An ecosystem consists of all the different
living & nonliving things in the year. A
healthy ecosystem supports all its living
things year after year.
The living parts of an ecosystem are called
biotic factors. Biotic factors include all of
the animals, plants, & microorganisms.
Community Interactions – Cont.
The nonliving parts of an ecosystem are its abiotic
factors. Abiotic factors include temperature,
precipitation, wind, soil, & all other nonliving parts
of the environment. The plants, animals, &
microorganisms of the ecosystem depend on one
another & the abiotic condition to stay alive.
Living things survive in all sorts of Ecosystems.
Living things depend on an ecosystem’s climate –
the average weather conditions from year to year.
Look at graphs on pg. B38 &39
What are the 2 parts of an
ecosystem?
 Biotic factors
 Abiotic factors
What are three abiotic
factors in an ecosystem? –
Test question
Temperature, precipitation, wind, soil,
water, rocks, sunlight.
Land Biomes
 Most species are best adapted to survive in
the conditions of their native biome. A
biome is a large group of similar
ecosystems with similar climates & living
things.
 The 6 main land biomes are: tundra, taiga,
grassland, temperate forest, tropical rain
forest, & desert.
 Look at the diagram on pg. B40
Tundra
The tundra is a cold biome w/ no trees. It
covers more than 10% of Earth’s land. Most
of it is located just south of the northern
polar ice cap. The tundra summer is short,
but the Sun shines almost constantly. Even
during the warmest summer days there is a
thick layer of ice just below the soil surface
called permafrost.
Tundra – Cont.
Short grasses, mosses, 7 shrubs grow in the
shallow layer of soil above the permafrost.
Lemmings, artic foxes, snowy owls, & musk
oxen live in the tundra year-round.
Adaptations, such as extra-thick coats of
fur or feathers, help them survive the harsh
coniditions.
Taiga (TY guh)
The taiga is an evergreen forest biome just
south of the tundra. The taiga is warmer &
wetter than the tundra.
Birth, fir, spruce, & hemlock trees grow in the
taiga. During the summer, ferns & mosses
grow in bogs. Grasses, shrubs, & flowering
plants grow on dry land.
These plants support many different animals.
Herbivores of the taiga include many:
insects, birds, squirrels, porcupines, deer,
elk, & moose.
Taiga – Cont.
Wolves, bears, & lynx depend on the
herbivores for food.
Residents of the taiga are adapted to survive
the cold. Most taiga animals spend their
summers storing up food & fat for the cold
winters. Some spend much of the winter in
hibernation, a type of deep sleep. This
helps them conserve energy & stay warm.
What is the difference
between a tundra & a taiga?
 The taiga is warmer & wetter than the
tundra. While trees grow in the taiga,
only low grasses, mosses & shrubs can
grow in the tundra.
Grassland
Grasslands are places that get enough rain for
grasses to survive. Long dry spells & fires
keep most trees from surviving.
Grasslands are found on every continent
except Antarctica. Some grasslands are
very cold, some are very hot, & some are
temperate- meaning cold winter & hot
summers. Most have wet & dry seasons.
Grassland animals must be either very quick
or good at hiding to survive.
Temperate Forest
Plants & animals flourish in temperate forests
because there is plentiful rainfall & sunlight.
Forests grow in areas that are warm for part
of the year & receive enough rainfall to
support trees.
Temperate forests are located south of the
taiga in the northern hemisphere & in many
other parts of the world. Temperate forest
winters are not as harsh as taiga winters &
summers are warmer.
What is the difference
between grasslands &
temperate forests?
There is more rainfall in the temperate
forest, so it supports trees. Grasslands
do not support trees.
Tropical Rain Forest
Tropical rain forests are found close to the
equator. This warm, wet biome has
tremendous biodiversity, which means that it
supports many species.
Competition in the rain forest is fierce! Plants
& trees compete for sunlight by growing
broad leaves all year long. The tallest trees
form a canopy of leaves over the forest that
absorbs most of the sunlight. When a leaf
drops, microorganisms quickly break it down
into soil. Plants absorb the nutrients quickly.
Desert
Deserts are places that receive little or no
rainfall. Because of their extreme dry
climate, deserts support few living things.
The desert biome is home to the toughest
plants & animals. They must have special
adaptations to survive.
Ocean Biome
Water covers almost ¾ of Earth’s surface. Water
biomes include freshwater biomes & saltwater
biomes, which include the ocean biome. As in land
biomes, the ocean biome depends on organisms
that use photosynthesis. Most food in the world’s
oceans comes from tiny algae & plankton near the
surface.
Different areas of the ocean, called zones, have
organisms suited to the conditions of each area.
The 3 zones are: intertidal, neritic, & oceanic
zones
Explain why many types of
plants & animals can live &
find niches in an ocean
environment. – Essay
Question
With different depths, different amounts of
sunlight, different temperatures, &
different current strengths, the ocean
provides many different habitats.
Ch. 6 Lesson 2
Every species in a ecosystem has a
niche, which includes the species’
relationships with the biotic & abiotic
factors of the ecosystem.
Niche
Each organism in an ecosystem has its own
niche or role in that ecosystem.
A species’ niche is its relationships with the
biotic & abiotic factors of the ecosystem.
In includes where it lives, & how it raises its
young.
Part of an animal’s niche is defined by what
it eats & what eats it.
Niche – Cont.
A predator is an animal, such as a bobcat,
that eats other animals, such as a rabbit.
The animal that is eaten – the rabbit – is the
prey.
Both predators & prey are adapted for their
niches. A bobcat can run fast & can easily
see & smell prey. Rabbits can also run fast
& their fur usually blends into it
surroundings.
Generalist
Some species are generalist, meaning they
occupy a broad niche. For example,
raccoons are predators that eat almost
anything. They dine on nuts, berries, birds,
fish, & even garbage.
Specialist
An organism with a specific niche will eat
only one kind of food.
Like the Wood Warbler’s, 5 different birds can
live in the same tree, because they all eat
different food, produce young at different
times, and live in different sections of the
tree.
An animal, such as a raccoon, that eats
many types of food is called a
generalist. An animal, such as a giraffe,
that eats just one type of food is called
a specialist. Which type of animal, the
generalist or specialist, would be better
adapted for survival in a changing
ecosystem? Why? – Essay Question
Generalists would be better adapted to a changed
ecosystem, because if one food source
disappeared they would have other sources of
food. A specialist would not be able to survive if its
main food source disappeared.
Food Web
A food chain describes the transfer of energy
from producers to consumers. A group of
overlapping food chain forms a food web. A
food web shows the feeding relationships,
or transfer of energy, within an ecosystem.
Although each ecosystem has a different food
web, all food webs have the same parts:
herbivores, carnivores, omnivores and
decomposers.
Food Web Organized
At the bottom of the food web is producers.
Next is the herbivores which are plant-eating
animals. Herbivores are primary
consumers, the 1st animal in any food chain.
Followed by carnivores & omnivores. Animals
that eat herbivores are called carnivores.
Carnivores are also consumers, but they
get their energy from eating other animals
that they hunt.
Food Web Organized
Omnivores get energy by eating both plants &
other animals.
Decomposers are organisms that feed on
dead plants & animals, breaking them down
into nutrients that enrich the soil.
This transfer of nutrients from plants to
animals to decomposers & back to plants,
occurs in every ecosystem.
Look at Desert Food Web diagram on Pg. B51
Healthy Ecosystems
In healthy ecosystems, populations of each
species are relatively stable. Each
population is big enough to reproduce &
small enough so that it does not use up all of
its food resources.
One important role in most ecosystems is the
top carnivore, such as eagles & lions. These
animals indicate that an ecosystem is
healthy, because they cannot survive without
healthy numbers of other plant & animal
populations.
Look at the Diagram on pg. B51 –
The snake in the picture is called
what part of the food web? What
would happen in this ecosystem if
all of the snakes died out? – Essay
Question
The snake is a carnivore. Because it eats
birds, small herbivores, and no plants. If all
of the snakes in the ecosystem died out,
then its prey, which are birds & small
animals, might increase in numbers.
Describe the relationship
between a predictor & its
prey. – essay question
In a predator-prey relationship, the predator
hunts & eats its prey.
Biomagnification
Read textbook pg. B52
Biomagnification – a biological process that
describes how an insecticide such as DDT
becomes concentrated in animals such as
hawks. – test question
Ch. 6 Lesson 3
Symbiosis describes a close
relationship between two different
species. – Test Question. Symbiotic
relationships include mutualism,
commensalism, & parasitism.
Mutualism
Mutualism is when 2 species both benefit
from the relationship between them.
Example: Clownfish & anemones. Anemones
use stinging tentacles to capture passing
creatures. The clownfish are immune to the
anemones stings so they live within the
anemones. The anemone keeps the
clownfish safe from predators. In return, the
clownfish keeps the anemones tentacles
clean & chases away “tentacle eating” fish.
They have a benefit/benefit relationship.
Commensalism
Commensalism is a relationship between 2
species in which one species benefits, while
the other species is neither harmed nor
helped.
Example: A robin builds a nest in an oak tree.
The robin gains a safe place to lay its eggs,
with no effect on the oak.
This is a benefits 1 specie/ neither helps or
harms species 2.
Parasitism
Parasitism is a relationship in which one organism
lives with another organism & harms it in some
way.
The harming organism is called a parasite.
(Tapeworm).
The harmed organism is called the host. (Humans or
animals)
By consuming from a living host, the parasite
maintains a constant food supply instead of only a
few meals.
Many parasites transmit diseases to their host.
Example: Lyme disease from ticks.
Examples of Parasites
Flea
Tick
More Examples
Tapeworm
Leech
Tapeworms
A tapeworm reproduces through a complex life
cycle. Its fertilized eggs are released into the
host’s intestines & eventually leaves the host’s
body in feces. The eggs may be eaten by
another animal, typically from contaminated
water or food. In the second host, the eggs
hatch into larvae & travel to muscle cells. There
they form inactive structures called cysts.
Humans & other animals become infected
when they eat cyst-laden meat.
Symbiosis with Humans
Large numbers of bacteria live in your large
intestines. These bacteria live on food that
has not been digested. Some of these
bacteria produce vitamin K & other
substances that human need. This is an
example of mutualism. This is a good
symbiosis relationship.
Humans can contract malaria which is a parasite
that kills about 2 million people a year. Most
of these people are from poor countries.
Is the relationship between
mosquitoes & humans a
parasitic relationship or a
predator – prey
relationship?
Essay Question.
It is a parasitic relationship because one
organism (mosquito) is helped & the other
organism (human) is harmed.