Transcript ch7 and 10 ppt part I

CHAPTERS 7 AND 10
Biomes And Terrestrial Biodiversity
BIOMES
• Large terrestrial regions with similar
characteristics- latitude is a key
• Climate is the most important factor in
defining a biome
• Precipitation is the main limiting factor for
vegetation found in a biome
(joshua tree is a xerophyte- lives without
much water - another example is the
bromeliad)
Natural Capital: Average Precipitation and Average
Temperature as Limiting Factors
There Are Three Major Types of Deserts
• Tropical deserts ex. Sahara-hot and dry
• Temperate deserts ex. Mojave
• Cold deserts ex. Gobi
• Fragile ecosystem
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Slow plant growth
Low species diversity
Slow nutrient recycling
Lack of water
Soil takes a while to recover
Desert Biomes
• Occur in interiors of continents
• Intense heat and evaporation during
the day and cooler nights due to rapid heat loss
• Little vegetation- plants have deep roots, roots that
spread out, spines, waxy leaves, no leaves, store
water in tissue (succulent), open pores at night
• Animals- long ears or legs to dissipate heat, thick
skin, small in size, sleep during the day
Threats to Deserts
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Overgrazing
Erosion/desertification
SUVs breaking the surface crust
Climate - change caused drought
Human population growth
Mining
There Are Three Major Types of Grasslands
• Tropical- Savanna
• Grazing animals
• Browsing animals
• Temperate
– Tall-grass prairies
– Short-grass prairies
-Winds blow continuously
• Arctic tundra: fragile biome
– Treeless plains, covered with ice and snow except
for about 8 weeks during summer when most plant
growth occurs
– Soils forms 17,000 ya
• Alpine tundra- occurs above limit of tree
growth but below permanent snow line.
Receives more sunlight than arctic tundra
Grasslands…
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Occur mostly in the interiors of continents
Experience seasonal drought
Are grazed by large herbivores
Experience occasional fires
Monoculture Crop Replacing Biologically Diverse Temperate
Grassland
Permafrost- underground soil which
is permanently frozen. Only the top layer
thaws.
• Found In The Arctic TUNDRA
• Permafrost keeps most snow melt from
draining into the ground. Many shallow
lakes, marshes, bog and ponds form.
Mosquitoes, black flies and other
insects serve as food for migratory birds
that nest and breed here.
Temperate Shrubland:
Nice Climate, Risky Place to Live
• Chaparral
• Near the sea: nice climateS. California, Mediterranean,
Central Chile
• Prone to fires in the dry
season and mudslides in
the rainy
season
There Are Three Major Types of Forests
• Tropical rain forests
– High temperature and moisture
– Stratification of specialized plant and animal
niches- high biodiversity
– Little ground level vegetation
– Rapid recycling of scarce soil nutrients
– Broadleaf, evergreen trees
– High net primary productivity
• Temperate deciduous forests
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Temperature and moisture
Broad-leaf trees
Slow rate of decomposition: significance
Nutrient-rich soil
• Evergreen coniferous forests: boreal and taigas
– Temperature and moisture
– Few species of cone: bearing trees
– Slow decomposition: significance
• Coastal coniferous forest- Scandanavia
• Temperate rain forests- Pacific NW (Olympic
National Rain Forest)
Why are Forests Important?
• Traditional medicines come from the forest
(80% of the population uses)
• Many chemicals are used in medicines
• Are habitats to 2/3 of all terrestrial species
• ¼ of world’s people depend on for their
livelihoods
Reintroducing
Gray Wolves to Yellowstone
• Around 1800-350,000 wolves over 48 states
• 1850–1900: decline due to human activity
(shot, poisoned, or trapped)
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U.S. Endangered Species Act: 1973 –only 100 wolves remained
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1995–1996: relocation of gray wolves to Yellowstone Park
– Helped to restore the biodiversity
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2008: Gray wolf is still endangered in many states, but not Alaska, Idaho,
Montana and several other states. The recovery is considered a great success
for the ESA.
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Is considered a keystone species- preys on elk that keeps many plant
populations in check (and then beavers and songbirds). Provide uneaten meat
for scavengers (vultures, bears, bald eagles, foxes…)
Sustaining Terrestrial Biodiversity
• Forests account for about 30% of Earth’s land
• Classified by age and structure
• Old-growth or primary forest –not disturbed for
200+ years
– 36% of world’s forests-high biodiversity
• Second-growth forest –secondary succession
– 60% of world’s forests
• Tree plantation, tree farm or commercial forest
(managed forest)
– 4% of world’s forests-low biodiversity
(1 or 2 species)
• May supply most of the industrial wood
in the future
Russia, Canada, Brazil, Indonesia, Papua New Guinea
• Most of the world’s forests are in
Russia, Canada, Brazil, Indonesia, Papua New
Guinea
• Most of the world’s tree plantations are in
China, India and the US
• Rubber tree plantation in China
Transitional Page
Unsustainable Logging is a Major Threat to
Forest Ecosystems
• Increased erosion
• Sediment runoff into waterways
• Habitat fragmentation
• Loss of biodiversity
• Invasion by
– Nonnative pests
– Disease
• Major tree harvesting methods:
– Selective cutting
– Clear-cutting
– Strip cutting
Building Roads into Previously Inaccessible Forests
Natural Capital Degradation
Building roads into inaccessible forests causes
destruction, and degradation
Major Tree Harvesting Methods
Advantages and Disadvantages of Clear-Cutting
Forests