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Ecology
• study of the interactions
of organisms with their
environments
– Biotic factors
• Organisms
• Populations
• Communities
– Abiotic factors
Abiotic factors
• Non-living components
– atmosphere is the gaseous
earth
• Nitrogen 78%, oxygen 21%,
& other gases, including
carbon dioxide (at 0.03%)
– hydrosphere is the aqueous
earth
• Surface water (rivers, lakes,
oceans, etc.), Water vapor,
Ice, Subterranean water
stores (aquifers)
– lithosphere is the rocky earth
• Rock, Soil, Sediment, Dust,
etc.
– Energy in its many forms
• Solar, Chemical, Mechanical
– In combination: temp., wind,
climate, etc
• Ecosystem
– Interactions of
living (biotic)
communities and
nonliving (abiotic)
physical and
chemical factors
• Biosphere
– Global ecosystem
• All of Earth’s
ecosystems
Limits of the biosphere
• Every interaction, at any
level, has consequences
– E.g. everything we do
affects the people that we
interact with and vice versa
– E.g. DDT a popular & very
effective pesticide of the
1950s
• Indirectly affected birds,
insects, waterways, milk,
etc
• Perhaps no part of the
biosphere is untouched
Rachel Carson, Silent Spring
Marine Ecosystems (oceans & seas)
Freshwater ecosystems
• Lentic systems
– Lakes & ponds
• Lotic systems
– Flowing water as in
rivers and streams
• Influenced by
nutrient levels and
productivity
Estuarine systems
•
Estuaries -- coastal areas
where saline and fresh
water mix
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Salinity highly variable
among the most productive
of all ecosystems
rapidly dwindling--primarily
due to development.
prone to eutrophication from
river flow contaminated with
fertilizer run-off and livestock
manure
Wetlands
•
•
Highly variable
Transitional
– Btwn aquatic & land
•
Examples
– Perpetually wet
mossy bogs and
tropical swamps
– Seasonally wet
vernal pools
– Estuaries
Terrestrial ecosystems or Biomes
•
Named for the dominant vegetation
–
•
Influenced by certain limiting abiotic factors
–
–
–
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•
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not necessarily the most common species, but most important to the
ecosystem
Temperature
Water availability
Soil type
General climate
Distribution affected
by latitude & altitude
Described by amount
of productivity
–
(total biomass)
Deciduous forests -- broadleaf forest, drop
leaves in winter; summers hot and humid;
winters cold; soil excellent; diversity
moderate
Coniferous forests -- evergreen forest, summers
more temperate; winters cold (except for some
coastal examples); soil poor; diversity low to
moderate; broad forests called Taiga, some
are fire adapted
Chaparral -- “scrub forest”; typical of
Southern Cal; summers hot and dry;
winters moderate and wetter; soil poor;
diversity low to moderate, tend to be fire
adapted
Temperate grasslands -- summers hot and
humid; winters cold; soil excellent;
diversity moderate to high; these are the
croplands of the world, are fire adapted
Tropical grasslands -- hotter than temperate
grasslands, droughts more severe;
sometimes called Savannah, are fire
adapted
Desert – very hot, very dry, poor soil, low
diversity
Tundra -- cold windy winters; short windy
summers; may have permafrost; plants
very low to ground, minimal root system
due to permafrost or minimal soil; soil
poor; diversity low
Tropical rain forest -- hot & humid; massive
rainfall; diversity high; soil poor (erodes
quickly, and nutrients tied up in biomass)