Post on 24-Dec-2015
Key Concept 1: How Does Climate Affect the Nature and Locations of Biomes?
Differences in average annual precipitation and temperature lead to the formation of tropical, temperate, and cold deserts, grasslands, and forests, and largely determine their locations.
Climate Affects Where Organisms Can Live
Major biomes• Similar climate, soil, plants, animals throughout
world• Ecotone
Latitude and elevation
Annual precipitation• Deserts, grasslands, forests
Temperature• Tropical, temperate, polar
Fig. 7-10, p. 147
ColdPolar
TundraSubpolar
TemperateConiferous forest
Desert
Deciduous forest
GrasslandChaparral Tropical
Ho
t
DesertW
et Rain forest SavannaTropical
seasonal forest
Dry
Scrubland
There Are Three Major Types of Deserts
Tropical deserts Temperate deserts Cold deserts
Fragile ecosystems• Hundreds of years for soil to recover from
disturbances• Slow plant growth• Low species diversity• Slow nutrient recycling (Why?)• Lack of water
Staying Alive in the Desert Plant adaptations
• Drop leaves or no leaves• Storage of water and food in fleshy tissue
• Take in CO2 only at night
• Deep roots to tap into ground water• Waxy coating on leaves
Animal strategies and adaptations• Small, hide during the day• Dormant• Camel – stores massive amounts of water, doesn’t sweat• Don’t drink – water from break down of fats in seeds• Think coverings• Dry feces and urine
There Are Three Major Types of Grasslands
Tropical• Savanna• Grazing animals• Browsing animals
Temperate• Tall-grass prairies• Short-grass prairies
There Are Three Major Types of Grasslands Cold (arctic tundra) – treeless plains• Can be referred to as desert• Fragile biome• Nutrient poor soil • Melting of permafrost
• Release CH4 and CO2 into the atmosphere
Adaptations of plants and animals• Thick fur or feathers• Living underground• Low growing plants
Alpine tundra – below permafrost snow line on mountains, more sunlight, more flowers
Temperate Shrubland: Nice Climate, Risky Place to Live
Chaparral Near the sea: nice climate• Significant human impact
Prone to fires in the dry season Maintained by fire, plants adapt with fire-resistant
roots, produce seeds that sprout after fire, use nutrients released by the fire
Soil thin and not very fertile
There Are Three Major Types of Forests (Dominated by Trees)
TROPICAL Tropical rain forests• Warm temperatures, high humidity, heavy rainfall• Dominated by broadleaf evergreen plants• Stratification of specialized plant and animal
niches• Emergent layer, canopy (most life forms),
understory, shrub layer, ground level• Little wind to spread seeds, depend on pollinators• Rapid recycling of scarce soil nutrients due to
warm, moist conditions• Immediately taken up by trees, poor soil
• Impact of human activities?
There Are Three Major Types of Forests
TEMPERATE Temperate deciduous forests• Moderate temperatures, abundant precipitation• Dominated by few species of broad-leaf trees• Drop leaves and become dormant in winter• Slow rate of decomposition: storehouse of
nutrients• Impact of human activities more than any other
biome
There Are Three Major Types of Forests
COLD Evergreen/Northern coniferous forests: boreal
and taigas• Long extremely cold and dry winters• Few species of cone-bearing evergreen trees• Low plant diversity• Slow decomposition: waxy coating on needles,
acidic soil, nutrient poor
Coastal coniferous forest/Temperate rain forests• Ample rainfall or moisture from dense ocean fog
Mountains Play Important Ecological Roles
Dramatic changes in altitude, slope, climate, soil, and vegetation
Majority of the world’s forests• Majority of world’s terrestrial biodiversity
Habitats for endemic species Sanctuaries for migrating animals (low to high) Help regulate the earth’s climate• Ice and snow reflect solar radiation back into space• Opposite – dark exposed rock absorbs energy?
Can affect sea levels Major storehouses of water - role in hydrologic cycle
Key Concept 2: How Have We Affected the Word’s Terrestrial Ecosystems?
In many areas, human activities are impairing ecological and economic services provided by the earth’s deserts, grasslands, forests, and mountains.
Fig. 7-20, p. 158
NATURAL CAPITAL DEGRADATION
Major Human Impacts on Terrestrial Ecosystems
Deserts Grasslands Forests Mountains
Large desert cities Conversion to cropland
Clearing for agriculture, livestock grazing, timber, and urban development
Agriculture
Soil destruction by off-road vehicles
Timber extractionRelease of CO2 to atmosphere from burning grassland Conversion of
diverse forests to tree plantations
Hydroelectric dams and reservoirs
Mineral extraction
Soil salinization from irrigation Increasing tourism
Overgrazing by livestockDepletion of
groundwaterDamage from off-road vehicles
Urban air pollutionIncreased ultraviolet radiation from ozone depletionLand disturbance
and pollution from mineral extraction
Oil production and off-road vehicles in arctic tundra
Pollution of forest streams
Soil damage from off-road vehicles