Download Secondary succession

Changes to the Environment
Succession
Primary Succession
Secondary Succession
Changes to Ecosystems
Role Of Humans
Changes to the Environment
Learning Objectives
• Compare and contrast the different types of ecological
succession
• Distinguish between the different environmental factors
that affect species
• Relate how limited resources affect population growth
Succession
• Populations interact to form a constantly changing
community
• Populations must adapt to changing conditions
• Ecological succession – the orderly change in the makeup
of a community over time
Succession
• Pioneer community –
the first inhabitants of a
new community
• Climax community – an
established community
that generally undergoes
little change
Succession
• Climax community gradually replaces pioneer community
Pioneer Community
Climax Community
Harsh environment
Favorable environment
Increasing biomass
Stable biomass
Inefficient energy consumption
Efficient energy consumption
Nutrient loss
Nutrient cycling
Low species diversity
High species diversity
Fluctuations common
Fluctuations uncommon
Primary Succession
• Primary succession – occurs in newly formed areas where
no organisms existed before
– Occurs where there is no soil
– Autotrophic prokaryotes are first to inhabit
Primary Succession
• Volcanic Eruption
1. Lichens and
mosses colonize
rocks
2. Lichens dissolve
rock, forming soil
3. As lichens/mosses
die, they add
organic matter to
the soil
4. Rich soil supports small animals, insects, and more plants
5. Barren rock becomes a terrestrial ecosystem
Secondary Succession
• Secondary succession – occurs after a preexisting climax
community has been partially or completely destroyed
– Natural disasters
– Land cleared for harvest or construction
– Occurs where soil is already present
Secondary Succession
• Abandoned cleared field
1. Weeds are pioneer
species
2. Dying weeds add
nutrients to the soil
3. New plants thrive,
creating shade
4. Pine forest becomes the
climax community
Secondary Succession
Primary Succession
Secondary Succession
No soil
Soil present
Pioneer species: autotrophic
prokaryotes, lichens, mosses
Pioneer species: herbaceous plants
Changes to Ecosystems
• Populations depend on
each other
• Kelp forest ecosystem
1. Sea otters eat sea urchins;
sea urchins eat sea kelp
2. If a disease kills the sea
otters, the sea urchin
population will increase
3. The sea urchins will
destroy the kelp forest
4. With no food, sea urchin
population declines
• Change that affects one
population can destroy
the entire ecosystem
Changes to Ecosystems
• Survival of a species
– Dependent on
maintaining population
size
– Must adapt to changes in
limiting factors
• Food
• Water
• Space
– Affects biodiversity
• Biodiversity – includes
the variation in life
within a given species,
ecosystem, biome or on
earth, along with the
complex interactions
occurring among species
– Currently decreasing
– Decline affects all life
Role of Humans
• Clearing land
– Destroys ecosystems
– Removes trees that
absorb CO2
• Coal-burning machines
– Releases CO2
• Increased CO2
– Greenhouse effect
– Global climate change
– Loss of biodiversity
Role of Humans
• Biomagnification – an
effect in which the
concentration of
pollutants in a food
chain dramatically
increases with each step
up in trophic level
Role of Humans
• Dams
– Displace communities
– Increase water-borne
diseases
– Trigger earthquakes
– Increase greenhouse
gasses
– Block fish migrations
– Increase erosion
– Cause loss of species
Role of Humans
• Burning of fossil fuels
– Releases CO2 and
nitrogen
– Greenhouse effect
– Global warming
– Acid rain
• Affects soil and water
• Kills plants
Role of Humans
• Excessive irrigation
– Erosion depletes
nitrogen from soil
– Poor plant growth
• Fertilizers
–
–
–
–
Excess nitrogen
Affects soil and water
Algal blooms reduce O2
Kills aquatic life
Role of Humans
• Decrease biodiversity
– Overhunting
– Introduced animals
• Spread disease
• Decimate natural
populations