Chapter 3
Ecology, ecosystems
and food webs
Ecology
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Groupings
Organism – single living thing
Species – several of same type of organism
Population – several of same species
interacting
Community – several populations interacting in
a certain area
Ecosystem – community interacting with each
other and the environment
Biosphere
Ecosystems
Communities
Populations
Organisms
Fig. 4.2, p. 72
Parts of the planet
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Planet as a solid – inner/outer core, mantle,
crust
Lithosphere is the crust and asthenosphere
Hydrosphere is the water regions
Atmosphere is the 5 layers of air
–
–
Troposphere (11 miles) 78% N2, 21% O2, 1% Ar
Stratosphere (11 – 30 mi) O3, blocks UV
Atmosphere
Biosphere
Vegetation and animals
Soil
Crust
Rock
core
Lithosphere
Mantle
Crust
Crust
(soil and rock)
Biosphere
(Living and dead
organisms)
Hydrosphere
(water)
Lithosphere
(crust, top of upper mantle)
Atmosphere
(air)
Fig. 4.6, p. 74
Incoming solar energy
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34% reflected by clouds
42% heats earth and atmosphere
23% evaporates water
1% creates wind
<1% photosynthesis
Solar
radiation
Energy in = Energy out
Reflected by
atmosphere (34%)
Radiated by
atmosphere
as heat (66%)
UV radiation
Absorbed
by ozone
Lower Stratosphere
(ozone layer)
Visible
Greenhouse
light
Troposphere
effect
Heat
Absorbed
by the earth
Heat radiated
by the earth
Earth
Fig. 4.8, p. 75
Greenhouse effect
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Solar energy (light) that reaches the earth is
converted into short wave radiation (heat)
infrared.
This infrared radiation has a hard time passing
through the gasses in our atmosphere thereby
trapping heat and keep the planet about 30
degrees (Celsius) warmer
Important gasses – H2O, CO2, CH4, N2O, O3
Biomes
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Large regions characterized by a distinct
climate and adapted vegetation
Remember climate is weather patterns over a
long period of time, usually several decades
Because certain plants are adapted to a
particular biome, so too are certain animals
which depend on those plants for food
Biomes
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There are not distinct boundaries between
biomes, rather there are ecotones.
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An ecotone is a blending of biomes and
generally carries a greater quantity and variety
of species
Components of Ecosystems
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Abiotic – nonliving
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Sunlight
Temperature
Precipitation
Wind
Latitude
Soil
Salinity (aquatic)
Terrestrial Ecosystems
Aquatic Life Zones
• Sunlight
• Light penetration
• Temperature
• Water currents
• Precipitation
• Dissolved nutrient
concentrations
(especially N and P)
• Wind
• Latitude (distance from
equator)
• Suspended solids
• Altitude (distance above
sea level)
• Fire frequency
• Soil
Fig. 4.13, p. 79
Components of Ecosystems
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Range of tolerance – how much of an abiotic
factor can an organism withstand
Limiting factor – the one factor that is holding
back a population from reaching its biotic
potential (max growth)
Important limiting factors in aquatic systems
–
Dissolved oxygen, salinity, temperature, light,
nutrients, etc.
Lower limit
of tolerance
Few
organisms
Abundance of organisms
Few
organisms
No
organisms
Population size
No
organisms
Upper limit
of tolerance
Zone of
Zone of
intolerance physiological stress
Low
Optimum range
Temperature
Zone of
Zone of
physiological stress intolerance
High
Fig. 4.14, p. 79
Food webs (chains)
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Producers (autotrophs) plants
–
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Using chemosynthesis (some bacteria)
Using photosynthesis (plants)
6 CO2 + 6 H2O + sun (yields) C6H12O6 + 6 O2
Plants convert only about 1-5% of the light they
absorb into chemical energy, and absorb only about
half the light that strikes them
Herbivores
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Primary consumers – eat producers (oh the
humanity)
–
Teeth designed for grinding
Carnivores
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Secondary consumers – meat eaters only
Feed on primary consumers (herbivores)
Teeth designed for tearing (large canines and
sharp molars) cats for example
Omnivore
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Tertiary consumer – eat anything, feeding on
other carnivores makes them tertiary
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We are omnivores, just look at our teeth,
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but we really should eat more veggies and less
meat (in my opinion)
The other consumers
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Scavengers – feed on dead organism they did not kill,
but found dead
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Detritivores – feed on parts of dead organisms
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Decomposers – bacteria and fungi, break down small
detritus into raw nutrients
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Biodegradable means can be broken down by
decomposers
Aerobic respiration
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Normal cellular process for most organisms
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Convert sugar and oxygen into energy leaving
water and carbon dioxide as products
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C6H12O6 + 6O2 yields 6 CO2 + 6 H2O + energy
Anaerobic Respiration
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Also called fermentation
The breakdown of glucose without oxygen
present
Produces: methane, ethyl alcohol, acetic acid,
and hydrogen sulfide
Food chains
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Trophic level – feeding level
First trophic level – plants
Second trophic level – primary consumers
Third trophic level – secondary consumers
Fourth trophic level – tertiary consumers
Remember heat is lost in every transfer
between trophic levels
Pyramid of energy flow
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Only about 10% of the usable energy transfers
between trophic levels (5-20%)
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For this reason we must rely on the transfer of
solar energy from producers to consumers
This is why it is so important to care for the
plants of this planet
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Biomass
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Organic matter produced by producers
(photosynthesis)
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Total dry weight of organic matter in plants and
animals in an ecosystem
Biomass Productivity
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Highest net biomass productivity per square
meter is in wetlands, estuaries, and rain forests
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Highest gross (but lowest per sq. meter) is the
open ocean. Because of its size it has a lot of
algae that add up to high productivity
Nutrient cycles
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Atmospheric – Carbon and Nitrogen
Sedimentary – Phosphorus and Sulfur
Hydrologic cycle – water cycle helps to
transport many nutrients
Hydrologic cycle
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Evaporation/transpiration
Condensation
Precipitation
Infiltration
Percolation
Runoff
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Powered by the Sun and gravity
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Carbon cycle
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Atmosphere
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Photosynthesis/respiration
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Fossil fuels
Limestone
Dissolved in the ocean
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Nitrogen cycle (very important)
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Nitrogen in the air
Nitrogen fixation by bacteria to ammonia
Nitrification by bacteria to nitrite NO2Nitrification by bacteria to nitrate NO3Assimilation by plants
Ammonification of dead organic material by
bacteria and fungi
Denitrification of nitrate by bacteria back to
atmosphere
Phosphorus cycle
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Very slow
Limited amount found in the soil
Limiting factor for plant growth
Excess causes prolific plant growth (algal
blooms in water)
We add phosphates to detergents/fertilizers
Sulfur cycle
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Passed as sulfates (salts) mostly
Hydrogen sulfide (swamps/volcanoes)
Sulfur dioxide (volcanoes)
Ammonium sulfate (sea spray)
Reacts in atmosphere to create hydrogen
sulfate (H2SO4) sulfuric acid (acid rain)
Ecosystem services
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Waste removal
Soil formation
Water purification
Air purification
Climate control
Recycling vital chemicals
Renewable energy
pest control
biodiversity
matter resources
aesthetic pleasure
Achieve sustainability
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Use renewable energy (especially solar)
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Recycle chemical matter
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REALIZE WE LIVE IN A CLOSED SYSTEM!
The END!!!