Transcript Ecosystems and Communities

Ecosystems and
Communities
Abiotic and Biotic Factors
 What
are abiotic factors?
 What are some examples of abiotic
factors?
 What
are biotic factors?
 What are examples of biotic factors?
Abiotic Factors
 Physical
or nonliving factors that
shape ecosystems.
 Temperature
 Moisture
 Wind
 Nutrient availability
 Soil type
 Sunlight
Biotic Factors
 The
biological influences on
organisms in an ecosystem.
 All the living organisms in an area.
The Niche
 The
physical and biological conditions
in which an organism lives and the
way that organism uses those
conditions.
 Includes:
– What it eats?
– How it gets the food it eats?
– What organisms use it for food?
Community Interactions
 Competition
– Occurs when organisms try to use a
resource at the same time in the same
place
– A resource could be water, nutrients,
light, food or space
Community Interactions
 Competition
often leads to a winner
and a loser.
 Competitive exclusion principle
– No two species can occupy the same
niche in the same habitat at the same
time
Community Interactions
 Predation
– One organism captures and feeds on
another organism
 Predator/prey
relationships
– Predator-does the killing and eating
 Wolf
– Prey-the food organism
 Deer
Community Interactions
 Symbiosis
– Any relationship in which two species
live closely together
 Mutualism
 Commensalism
 Parasitism
Community Interactions

Mutualism– Both species benefit from the relationship
– Flowers and insects

Commensalism
– One species benefits and the other is not
helped or harmed
– Barnacles and whales
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Parasitism
– One species benefits while the other is harmed
– Tick and dog
Ecological Succession
 Is
a series of predictable changes
that occurs in a community over
 Two main types: primary and
secondary
Primary Succession
 Begins
in a lifeless
area with no soil as
in a lava flow.
 Starts with bacteria,
then to lichens and
mosses, on to
grasses and so on.
 The first species to
populate the area are
called pioneer
species.
Secondary Succession
A disturbance has
destroyed the
community but left
the soil.
 Old field succession
is an example.

Biomes
A
major terrestrial or aquatic life
zone
 Characterized by soil, climate, plants
and animals
Biomes and Climate
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The climate of a region determines what can
survive in that region.
Main components of climate are temperature and
precipitation
Climate diagram
Terrestrial Biomes
 Are
grouped based on their
vegetation type.
 Geographic distribution of plants
depends on amount of available
water and on the temperature.
How many terrestrial biomes are
there?
Although there is some disagreement among scientists on
how to divide up the Earth’s biomes, most can agree on
the following eight:
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Tropical Rainforest
Tropical Savanna
Desert
Chaparral
Grassland
Temperate Deciduous Forest
Temperate Boreal Forest
Tundra
Tropical Rainforest
Typically found near the
equator
 Receives more than 200
cm of rain annually
 Temperatures typically
fall between 20oC and
25oC for the entire year
 As many as 50% of all
the world’s animal
species may be found
here
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Chaparral
Also called the
Temperate Woodland
and Shrubland
 Found between 32o and
40o latitude on the
west coast of
continents
 Receives between 35
and 70 cm of rain,
usually in the winter
 Extremely resistant to
drought and weather
events
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Savanna
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Grasslands with a few
scattered trees
Experience a wet and dry
season
Hot temperatures
Annual rainfall is between 50
and 127 cm
More species of grazing
mammals than any other
biome
Desert
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Typically found between
25o and 40o latitude
Receives less than 25 cm
of rain each year
Temperatures typically
range between 20oC and
25oC but some extreme
deserts can reach
temperatures higher than
38oC and lower than –15oC
Grassland
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Because of the dry climate,
trees are found only near
water sources such as
streams
Usually receives between
50 and 90 cm of rainfall
each year
Summer temperatures can
reach up to 38oC, and
winter temperatures can
fall to –40oC
Temperate Deciduous Forest
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Moderate climate
Most trees will lose their leaves
in the winter
Temperatures range between –
30oC and 30oC
Averages from 75 to 150 cm of
precipitation
Well developed understory
Coniferous Forest
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Also known as Taiga
Typically found between 45o and
60o North latitude
Cold climate with summer rains
Very few reptiles
Limited understory
Snow is primary form of
precipitation (40 – 100 cm
annually)
Tundra
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Means treeless or marshy
plain
Characterized by permafrost –
permanently frozen soil
starting as high as a few
centimeters below the surface
– which severely limits plant
growth
Winter temperatures average
–34oC while summer
temperatures usually average
below 10oC
Low precipitation (15–25 cm
per year) but ground is
Aquatic Biomes
 Occur
about 75% of Earth’s surface
 Determined by their salinity
 Freshwater biomes have less than
1% salinity
 Marine biomes are about 3% or more
Freshwater Biomes
 Cover
less than 1% of Earth and
have about 0.01% of Earths water.
 But about 6% of all living species are
here
 Plus we depend on this biome for
drinking water, crop irrigation,
sanitation and industry.
Lakes and Ponds
 Standing
bodies of water that can be
very small farm ponds to the Great
Lakes.
 Living organisms are distributed by
the depth of the body of water and
by the distance to shore.
Lake and Pond Layers
Photic Zone: light
is available for
photosynthesis
Aphotic zone:
light levels are
too low for
photosynthsis
Benthic zone:
the bottom of the
lake or pond
Rivers and Streams
 Flowing
bodies of water
 Characteristics change between its
source and the point it empties into a
larger body of water (lake or ocean)
 Source: water is cold, low in
nutrients and clear, runs fast
 Downstream: water gets warmer,
slows down
 Greatly affected by human activity.
Rivers and Streams
Wetlands
 Transitional
biome between aquatic
and terrestrial biomes
 Freshwater: bogs, swamps and
marshes
 Covered at least part of the time
with water
 Provide flood control by storing water
 Improve water quality by trapping
pollutants and organic compounds in
sediments
Wetlands
Marine Biome
 Varies
by depth
 Some areas receive sunlights; some
don’t
 Photic and Aphotic zones
 Photic: extends down to a maximum
of 200 m
 Aphotic: 200m and beyond
Marine Layers
Marine Layers
 In
photic zones
– Photosynthesis is done by
phytoplankton and multicellular algae
Marine Organisms
Intertidal Zone
 Where
ocean meets land
 Waves pound the shore at high tide
 Exposed to wind and sun at low tide
Estuary
 Transitional
area between rivers and
ocean
 Saltiness varies from nearly
freshwater to the same as the ocean