Biodiversity
Environmental Science Unit 2
SEV2. Obtain, evaluate, and communicate information to construct
explanations of stability and change in Earth’s ecosystems.
Intro to Unit 2: Biodiversity
• Ecosystems are always changing.
• Living (Biotic) and Non-Living
(Abiotic) aspects of the ecosystem
change over time.
• Changes can happen quickly or take
a long time.
• Changes can occur in many ways.
• Even small changes can impact the
entire ecosystem.
Limiting Factors
• One of reasons that small
changes can have big impacts
is that ecosystems are limited.
• Limiting factors can be biotic
or abiotic resources.
• Examples: Temperature,
water, precipitation, nutrient
availability, food sources,
sunlight, disease, soil type,
salinity, dissolved oxygen
Carrying Capacity
• Due to limiting factors,
ecosystems have a carrying
capacity.
• The carrying capacity is the
amount or number of
organisms that an ecosystem
can support.
• The carrying capacity means
organisms within the ecosystem
must compete for resources.
Competition
• Competition is one way
organisms interact with
each other.
• Organisms compete for
food, water, shelter, mates,
and many other things.
• There are many more
types of interactions.
Stable Ecosystems
• The complexity of interactions
within an ecosystem keeps the
number of organisms
constant, so the ecosystem
can remain stable for a long
time.
• When small changes happen
to a stable ecosystem , the
ecosystem can recover.
Changing Ecosystems
• Large fluctuations in populations
can hurt the stability of an
ecosystem.
• Larger populations require more
resources and habitats can
change.
• These fluctuations can change
the makeup of the ecosystem.
Speciation
• When the environment changes,
the ecosystem can change.
• Species best suited for the new
environment become more
plentiful.
• Some species can diverge due to
species being separated for a long
time.
• An increase in biodiversity can
happen due to speciation.
• Biodiversity can decrease by
extinction.
Cyclic Changes
a.
Analyze and interpret data related
to short-term and long-term natural
cyclic fluctuations associated with
climate change.
Short-term examples include but are not limited
to El Niño and volcanism. Long-term examples
include but are not limited to variations in Earth’s
orbit such as Milankovitch cycles
Cyclic Changes
• Earth experiences short-term and
long-term natural cyclic
fluctuations.
• Short-term fluctuations affect
climate for months to years.
• Examples of short-term
fluctuations:
• El Nino
• Volcanism
El Niño
• El Niño leads to changes in the jet streams over North America.
• During El Niño:
• the northern part of North America is dryer
• the southern part of North America is wetter
• El Niño occurs every 2-7 years, but there is no set schedule
• It happens when trade winds reverse
• Normal trade winds blow from the east coast of North America towards
Europe
• When they reverse, they blow from Europe to North America
El Niño
• El Niño can
mean droughts,
floods, crop
failures, and
looming food
shortages.
Volcanism
• Volcanism is the eruption
of molten magma to the
Earth’s surface
• Volcanoes have a shortterm impact on the
climate due to the ash
and gases released into
the atmosphere.