CHAPTERS 7 AND 10Biomes 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– Slow plant growth– Low species diversity– Slow nutrient recycling– Lack of water– Soil takes a while to recover

• 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

Desert Biomes

Threats to Deserts

• 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…

• 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 climate-

S. 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– 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)

• U.S. Endangered Species Act: 1973 –only 100 wolves remained

• 1995–1996: relocation of gray wolves to Yellowstone Park – Helped to restore the biodiversity

• 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.

• 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 inRussia, 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

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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 ForestsNatural Capital Degradation

Building roads into inaccessible forests causes destruction, and degradation

Major Tree Harvesting Methods

Advantages and Disadvantages of Clear-Cutting Forests