Download ENVI 30 Environmental Issues

Fig. 52.18
I.
Ecology
A.
Biotic Factors
1.
Competition
2.
Predation
3.
Disease
4.
Parasitism
Fig. 52.20
I.
Ecology
B.
Abiotic Factors
1.
Temperature
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2.
Temperature and temperature variation extremely
important
Cells may rupture at very cold temperatures
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Why don’t trees freeze and explode?
Proteins denature at sustained high temperatures
(usually >45 oC)
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Some bacteria can survive at >90 oC
Water
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Essential to life
Availability varies
Terrestrial organisms always fighting desiccation
Aquatic organisms struggling with osmotic stress
I.
Ecology
B.
Abiotic Factors
3.
Sunlight
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4.
Wind
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5.
Amplifies temperature variation through evaporation and
convection
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Ex: Wind chill factor
Affects rates of water loss, growth forms of plants
Rocks and Soil
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Provides vast majority of energy for living systems
Affects distributions of terrestrial organisms
Affects depth distributions and sensory systems of aquatic
organisms
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Intensity and spectrum change with depth
May affect behavior
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Ex: DVM, activity patterns
Physical structure, pH, mineral composition, organic content
Aquatic sediments affect water chemistry
First four factors (temperature, water, light, wind) are major
components of climate (long-term patterns)
I.
Ecology
C.
Climate Effects
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Affects geographic distribution (range) of
species
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Affects survival, reproduction, dispersal
Silver-Washed Fritillary (Argynnis paphia)
Fig. 52.8
II.
Population Ecology
A.
Density and Dispersion
1.
Density
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Number of individuals + size of habitat
May be influenced by resource availability,
disturbance
May vary over time
How do we measure organismal densities?
1) Complete census
2) Subsample (quadrats, transects, single taxon)
3) Indicators of density (tracks, scat)
4) Mark-recapture
Not static over time