Download Chapter 20 Community Interactions

Ecosystems and
Communities
Chapter 20
The role of Climate
 What
is climate?
– Temperature, precipitation, other
environmental factors combine to
produce weather and climate.
Greenhouse Effect


This is a natural
situation!!
Carbon dioxide,
methane, water
vapor and other
gases trap heat
energy and
maintain the
Earth’s
temperature range
The Effect of Latitude on climate
 How
does the position of the sun in
the sky effect climate? (see the next
slide for the answer)
The Earth has three main climate
zones:
polar
temperate
tropical
Different latitudes have different
angles of heating, affecting climate
Heat Transport in the Biosphere

Unequal heating and cooling drives winds
and ocean currents.
What Shapes an Ecosystem?
 Key
concept: Biotic and abiotic
factors determine the survival and
growth of and organism and the
productivity of the ecosystem in
which the organism lives.

Biotic Factors
– All living things in
an ecosystem

Abiotic Factors
–
–
–
–
–
–
–
Temperature,
Precipitation
Humidity
Wind
Nutrient availability
Soil type
Sunlight
The Niche
 An
organisms occupation in its
environment is it’s niche.
 This includes the following factors
– Type of food
– How it obtains food
– Which other species use the organism
as food
– Physical conditions.
WARNING
WARNING
No two species
can share the
same niche in the
same habitat.
Community Interactions
 Community
interaction, such as
competition, predation and various
forms of symbiosis can powerfully
affect an ecosystem

Competition
– Happen when two
organisms try to
use the same
resource in the
same place at the
same time
– A Resource is:
water, nutrients,
light food, or space.

Competitive
Exclusion Principle
– No two species can
occupy the same
niche in the same
habitat at the same
time!!!
Predation

An interaction in which one organism
captures and feeds on another.
Symbiosis: Living together closely
Mutualism:
both species
benefit
+/+
Commensalism
One
member
benefits and
the other is
neither
helped nor
harmed
+/0
Parasitism
 One
organism
lives on or
inside another
organisms and
harms it.
+/-
Patterns in Communities
 Species
richness
– The number of
species in the
community
– A simple count of
the species in a
community
 Species
evenness
– The relative
abundance of
each species.
– How common
each species is.
Latitude and species richness
 Species
richness
varies with
distance from
equator—closer
to equator =
more species
 Habitat
size:
greater the area
will contain more
species than a
small area.
 Species
interactions will
affect species
richness
 Species richness
influences how a
community
responds to a
disturbance.
Ecological Succession
 Ecosystems
are constantly changing
in response to natural and human
disturbances.
 As
an ecosystem changes, older
inhabitants gradually die out and
new organisms move in, causing
further changes in the community
The series of predictable changes
that occur in a community over
time.

Primary succession
– Succession that
occurs on surfaces
where no soil
exists.
Primary succession
 Occurs
on the surfaces formed as
volcanic activity builds new islands or
covers the land with lava or volcanic
ash.
 Also occurs on bare rock exposed
when glaciers melt.
 The first species to populate an area:
pioneer species
Secondary Succession
A
disturbance of some kind that
changes an existing community
without removing the soil.
 Caused by farming, wildfires
 The series of predictable changes
ends with a mature, stable
community called a climax
community
Climax community
Secondary Succession
Biomes
 There
are at least 10 different
biomes.
 Each
of these biomes is defined by a
unique set of abiotic factors and has
a characteristic ecological community
What is this biome?
What biome is this?
Name That Biome!!
What biome is this?
Last but not least…
Water, water everywhere…
 Aquatic
ecosystems are determined
primarily by the depth, temperature,
flow, and chemistry of the overlying
water.
Freshwater ecosystems
 Flowing
water: rivers and streams
 Standing water: lakes and ponds
 Wetlands: marshes and swamps
 Estuaries: where rivers meet the
sea.
– Contain a mixture of fresh and salt
water
– Salt marshes and mangrove swamps
are examples.
Marine Ecosystems
 Divided
into two zones based on the
amount of light penetration.
– Photic zone: well-lit upper layer down to
about 200 meters. Photosynthesis
possible.
– Aphotic zone: permanently dark. Only
producers in this zone are
chemoautotrophs.
Marine ecosystems continued.
 Scientists
also divide the ocean into
zones based on the depth and
distance from shore.
– Intertidal: subject to tides
– Coastal ocean: from the low tide mark
to the edge of the continental shelf.
Contain coral reefs in tropical areas.
Marine ecosystems cont.
 Open
Ocean: from the continental
shelf and extends outward
– Largest marine zone
– Organisms in the deep open ocean have
adapted to great pressure, freezing
temperatures and no light
Benthic Zone: the ocean floor.