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Ecology Basics
6 major terrestrial biomes
• TRF
• Desert
• Tundra
• Deciduous Forest
• Coniferous Forest
• Grasslands
• Elevation
• Precipitation
• Substrate
Aquatic biomes
• Biomes that occur in the water differ
from terrestrial biomes.
• The major distinction in aquatic (water)
biomes is whether or not the biome is
comprised of salt or fresh water.
• Therefore the 2 main aquatic biomes
are fresh water biomes and marine
biomes.(Salt containing)
Special Aquatic Biomes
• Estuaries are special aquatic biomes as they occur
any where freshwater meets saltwater.
• Does Arizona have any estuaries?
Marine Zones are based on 2
main traits.
• Depth (which
impacts)
– Light
– Pressure
– Temperature
• Contact with
coast (which
impacts
habitat)
Specific Marine Sub-zones
A)Intertidal/Neretic – highly photic has
contact with coast
B) Open Sea/Oceanic – photic but no
contact with the coast
C) Open Sea/Pelagic - non-photic no
contact with land
D) Deep sea/Benthic - non-photic, cold
temps and high pressure
Clean up crew!
• Detritivores- (Detritus feeders) aka
scavengers-EX:
– Larger –will be regulated on energy
pyramid (as secondary consumer)
because of size.
• Decomposers- EX:
– Smaller-does not get regulated on energy
pyramid because of size.
• BOTH heterotrophs that feed on nonliving organic matter…..
Ecological Population
Dynamics
Biotic potential
• The maximum number of offspring an
organism can produce is its biotic
potential.
• What keeps organisms from reaching
their full biotic potential?
• Environmental limits (not enough food,
water, shelter or things like disease,
predation). These limits are called
environmental resistance.
Population Growth Models
Exponential model
• idealized
• Called “r populations”
(J-curve)
Logistic model
• realized
• Called “K populations”
(S-curve)
Which one happens most
often? Why?
Strategies to increase biotic
potential
• r-selected
•
•
•
•
•
(opportunistic)
Short maturation &
lifespan
Many (smaller)
offspring
No/little parental care
High death rate
EX:?
• K-selected
(equilibrial)
• Long maturation &
lifespan
• Few (larger)offspring;
• Extensive parental care
• Low death rate
• EX:?
Population limiting factorsEnvironmental resistance!
• Density-dependent
factors: • limited food water,
shelter •predation • disease
• Density-independent
factors •weather/climate
• These factors lead to K*
• (*K=The max number of
individuals an area can
sustain/Carrying capacity)
• Biotic potential vs
Environmental resistance!
(All life must deal with this)
• Leads to adaptation
Chemical Cycling
Chemical Cycling
Biogeochemical cycles: the various nutrient
circuits, which involve both abiotic and
biotic components of an ecosystem
•
•
•
•
Water
Carbon
Nitrogen
Phosphorous
.
Nitrogen Cycle
• Nitrogen enters the atmosphere, in gaseous form
N2. It has to be transformed into a usable form for
organisms to use.
• Nitrogen fixing bacteria convert N2 into NH4 in a
process called nitrogen fixation.
• NH4 is also produced by decomposers when
breaking down organic matter in a process called
ammonification.
• Different bacteria take NH4 and covert it into nitrite
(NO2-) and nitrate (NO3-) in a process called
nitrification. (This allows producers to use the
nitrogen now, assimilation)
• Denitrifying bacteria convert nitrate (NO3-) back
to N2 for release back into the atmosphere.
Phosphorous
Key Terms
Leaching
Weathering
Runoff
Chemical
Precipitation
Sedimentation
Are ecosystems static or
dynamic?
Big Changes in the system
• Primary
succession- going
from nothing (no
soil)to pioneering
community to
climax
community.
• Why would there
be nothing???
– Melting glaciers
– Volcanic
eruptions
– Landslides
– Strip mines
• Secondary Succession - Re-establish an
ecosystem after a disturbance
• What could be a possible disturbance?
– Flood
– Fire