Download ecosystem 2 apes nitro minus video

The Nitrogen Cycle
The nitrogen cycle
• Living things need
nitrogen to make
protein.
• They can not use the
nitrogen that is 78% of
the air
• The nitrogen in the air
must be changed to
before plants can use
it.
The nitrogen cycle
• Animals get
their
nitrogen by
eating
plants.
The nitrogen cycle (page 70)
Nitrogen fixation
• N2 (gas)NH3(ammonia)
• Cyanobacteria and
Nitrogen-fixing bacteria
living in these nodules on
plant roots can do this
conversion.
Nitrogen cycle…
• Assimilation
– Producers take up nitrogen
– Process in which consumers get nitrogen from
producers
• Ammonium NH4+ or nitrate NO3-
The nitrogen cycle
• The nitrogen-fixing
bacteria are essential
to maintain the
fertility of the soil.
• Without them food
yields would rapidly
fall.
• Considered limiting
factor
Nitrogen cycle…
• Ammonification
– Decomposers in soil and water break down
the biological nitrogen back into NH4+
Nitrogen Cycle…
• Nitrification
– Nitrifying bacteria convert ammonium, NH4+,
to nitrite, NO2- and then into nitrate, NO3-
Nitrogen cycle…
• Denitrification
– Denitrifying bacteria convert nitrate into
nitrous oxide and then nitrogen gas
Perhaps catchy way to remember…
fix NAAD ANPAN
Process
• Fix-nitrogen
fixation
• Nitrification
• Assimilation
• Ammonification
• Denitrification
Product
• Ammonia NH3
•
•
•
•
Nitrates
Proteins
Ammonia (nitrites)
Nitrogen
Phosphorus Cycle
• Very slow cycle.
• Almost all found in the ground.
• Cycle impacted by fertilizer and
laundry soap form 1940-90, dish
soap ‘til 2010
• Limiting agent in most ecosystemstherefor increase has big impact
excess can cause algal bloom
Phosphorus Cycle
Algal Bloom
• Algal blooms are the result of an
excess of nutrients, particularly
phosphorus and nitrogen.
• The excess of nutrients may
originate from fertilizers, these
nutrients can then enter watersheds
through water runoff.
• Creates hypoxic (low oxygen
conditions)
Algal bloom
Succession (Chapter 6)
• How ecosystems change over time.
– Change and replacement of species
• Gradual process (100-1000s of years)
• 2 Types
– Primary- occurs where no ecosystem existed
before.
– Secondary- occurs where ecosystem
previously existed. More common
Primary Succession
• Occur by
– Volcanic eruptions creating new islands
– Areas exposed when glaciers retreat
– Any area that did not have life prior
• Slower (several thousand years)
• First species present (pioneer) will be
bacteria and lichens
How it gets started
• Bacteria and lichens can start on bare
rocks and break them down.
• Water than enters rock to freeze and thaw
which breaks it further.
• Mosses decay and add to soil…more life
can start
Secondary Succession
• Created by
–Natural disaster wipes out existing
ecosystem and new one is started.
–Fire-manmade or lightening. Some
ecosystems depend on lightening.
–Old field succession is process
where abandoned farmland grows
back to forest.
Process of secondary succession
• First you have grasses
• Then small bushes, they choke out some
of the grasses
• Small trees start to grow and they choke
out some of the bushes
• Then trees get larger….
Ecosystems respond to disturbance
• Disturbance- An event caused by physical,
chemical or biological agents that results in
changes in population size or community
composition.
The Intermediate Disturbance Hypothesis
• The intermediate disturbance hypothesisstates that ecosystems experiencing
intermediate levels of disturbance are more
diverse than those with high or low
disturbance levels.
Resistance versus Resilience
• Resistance- A measure of how much a disturbance
can affect its flows of energy and matter.
• Resilience- The rate at which an ecosystem returns
to its original state after a disturbance.
• Restoration ecology- A new scientific discipline
that is interested in restoring damaged ecosystems.