Biomes Animals and plants have narrow What defines a biome ...ncrane/ES 10/BiodivbiomesF10.pdf ·...
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12/1/10 1 Biomes • What defines a biome? • Where are the ‘lines’ drawn? • What are the major controlling factors? • What about aquatic ‘biomes’ Biomes • Animals and plants have narrow ranges of tolerance to abiotic factors • 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 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Tolerance limits Figure 3.2 3-1 Figure 50.3 A climograph for some major kinds of ecosystems (biomes) in North America Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. World biome map Figure 5.3 5-1 Figure 50.9 The distribution of major aquatic biomes
Transcript of Biomes Animals and plants have narrow What defines a biome ...ncrane/ES 10/BiodivbiomesF10.pdf ·...
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Biomes • What defines a biome? • Where are the ‘lines’ drawn? • What are the major controlling factors? • What about aquatic ‘biomes’
Biomes • Animals and plants have narrow
ranges of tolerance to abiotic factors
• 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
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Tolerance limits Figure 3.2
3-1
Figure 50.3 A climograph for some major kinds of ecosystems (biomes) in North America
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
World biome map Figure 5.3
5-1
Figure 50.9 The distribution of major aquatic biomes
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Figure 50.13 Zonation in the marine environment Figure 50.8 Lake stratification and seasonal turnover
Figure 50.10 Zonation in a lake Currents
Aquatic Biomes • Temperature • Currents • Nutrients • Salinity • Oxygen • Depth • Sunlight
• Physical as well as chemical boundaries
Some Key Points • 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.
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Biodiversity “hot spots” Figure 5.20
5-6
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Natural medicinal products
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Biodiversity
• 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??
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Human disturbance
5-9
Extinction
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.)
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
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Extinction 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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Mass extinctions
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Extinction
What makes a species extinction prone?
• Critical population size • Specialists vrs. Generalists • Animal size (large) • Range (small) • Trophic position (high) • Tolerance to humans • Behavioral patterns
Passenger pigeon-now extinct
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Reproductive strategies
3-10
Carbon dioxide Temperature
Sea level Arctic ice
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320 ppm: occasional bleaching 320 ppm: occasional bleaching
CO2 in summary
345 ppm: sporadic mass bleaching
387 ppm: inevitable long-term decline
450 ppm: rapid decline, reefs cease to be biodiverse
600 ppm: acidification affecting all biota
800 ppm: mid Eocene extinction conditions
1000 ppm: reefs only geological structures. Sixth Mass Extinction
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U.S. wetland acreage Figure 5.24
5-10
Refugia and habitat fragmentation
Some organisms CAN survive in these refugia, but may never get out, or may emerge quite changed
Life on Earth • Living things cause change • Living things respond to change • Living things change their environments • Living and non-living components of our Earth
interact • Processes like global warming/climate change
follow large-scale patterns, but it is the composition of life on earth that can affect those patterns
• Ecological systems exist in balance - that balance can be disturbed, and its evolution from there can be difficult to predict.
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Endangered species
5-13
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Protected lands Figure 5.33
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