Biomes
Biomes
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• Animals and plants have narrow
ranges of tolerance to abiotic factors
What defines a biome?
Where are the ‘lines’ drawn?
What are the major controlling factors?
What about aquatic ‘biomes’
• This in part determines the biotic
components of biomes. These are
broad geographic regions determined
by temperature and rainfall, and
described by their plant communities
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Figure 50.2 Patterns of distribution in the biosphere
Tolerance limits
Figure 3.2
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Figure 50.3 A climograph for some major kinds of ecosystems (biomes) in North
America
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World biome map
Figure 5.3
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Figure 50.16a-d Examples of terrestrial biomes: maps
Biome climate graphs
Figure 5.4
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Figure 50.16e-h Examples of terrestrial biomes: maps
Biomes
Figure 50.16b Savanna
Figure 50.16c Desert. Organ Pipe State Park (top), Joshua Tree National Park
(bottom left), Death Valley
(bottom right)
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Figure 50.16a Tropical forests
Figure 50.16h Tundra. Denali National Park (left), reindeer (right)
Figure 50.16e Temperate grassland
Figure 50.16f Temperate deciduous forest, Great Smokey Mountains National Park
Figure 50.14 Marine biomes
Figure 50.9 The distribution of major aquatic biomes
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Figure 50.13 Zonation in the marine environment
Biomes
Figure 50.8 Lake stratification and seasonal turnover
Figure 50.10 Zonation in a lake
Figure 50.11 Freshwater ecosystems. Oligotrophic lake (left), eutrophic lake (right)
Sea surface temperature
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Salinity
Currents
Aquatic Biomes
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Some Key Points
Temperature
Currents
Nutrients
Salinity
Oxygen
Depth
Sunlight
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Animals interact with biotic and abiotic factors in ways which shape
their survival and distributions
Biomes are delineated by abiotic factors, but biotic factors play a role
too.
Biomes are described by plant communities which are ‘controlled’ by
temperature and precipitation
Oceans are different: currents and salinity/oxygen distribution have a
major impact - productivity
Organisms have tolerance ranges to abiotic factors - both long term
and short term effects.
• Physical as well as chemical boundaries
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Biodiversity “hot spots”
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Natural medicinal products
Figure 5.20
5-6
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Biodiversity
Human disturbance
• Species diversity: number of different
species
• Genetic diversity: ensuring a healthy
gene pool-problems with bottlenecks
• Ecological diversity: numbers of ‘habitat
types’ - relates directly with species
diversity
• But WHY is it important??
5-9
Extinction
Extinction
Human accelerated extinction
• Most major mass extinction in the last 65 mill yrs
is now (cretaceous), by us.
• 40-100 sp. going extinct every day: unparalleled
• 1000-10000 times natural background rate what’s cause?
• possibly 20% of current species extinct in next 30
yrs - more than have been named yet!
• Fastest moving aspect of global change
• Irreversible
Natural extinction
• Extinction is a natural process. As
earth changes, so does it’s flora and
fauna.
• Periods of mass extinctions and
radiations (diversity)
• Extinction has to keep up w/
speciation. (~1 per 1000 yrs.)
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Extinction
Mass extinctions
What causes extinctions?
• Natural events - climate change, etc.
• Habitat loss and disturbance
• Commercial hunting and poaching
• Predator and pest control
• Pets/decorative plants
• Introduction of non-natives
• Population growth, affluence and
poverty
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Extinction
Reproductive strategies
What makes a species extinction prone?
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Critical population size
Passenger pigeon-now extinct
Specialists vrs. Generalists
Animal size (large)
Range (small)
Trophic position (high)
Tolerance to humans
Behavioral patterns
3-10
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U.S. wetland acreage
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Endangered species
Figure 5.24
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Protected lands
Figure 5.33
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