L12+_28+Sep_+Climate+and+earth_s+major+ecosystem+II+_Lee_

L12+_28+Sep_+Climate+and+earth_s+major+ecosystem+II+_Lee_ -...

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BISC 003 Environmental Science: Climate & Earth’s Major Ecosystems (CH. 5)
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Major Ecosystems h Terrestrial Biomes: Tropical rainforest Tropical seasonal forest Desert h Aquatic ecosystems: Marine s Coral reefs s Mangroves stuaries Grassland Temperate forest Coniferous forest Savanna Tundra s Estuaries Freshwater s Wetlands
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Deserts h 1/3 of the Earth’s land surface h Dry, where evaporation exceeds precipitation . h Receiving an average rainfall of <25 cm/year <2.5 cm of rainfall er year: lmost no per year: almost no vegetation . 2.5-5.0 cm rainfall have sparse (<10%) vegetation . h Found at about 30 o north and south (e.g. continental interiors of N. America, Central Asia, Africa and Australia
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Deserts h Large daily and seasonal temperature fluctuations High daytime temperature as high as 45 o C Low nighttime temperature (due to extremely low humidity). Dry air incapable of trapping heat. h Often composed of sand and rocky surfaces Sand dunes Stony surfaces Minimal soil development, which is easily disturbed by human activities, and slow to recover.
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Fauna adaptations h Often have high biodiversity h e.g. Kangaroo rat, pocket mice, jack rabbit, lizards h Adaptations nimals remain hidden Jerboa Animals remain hidden during day Feed at night Most can acquire all their water from seeds and vegetation they eat. Highly concentrated urine and dry feces
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Flora adaptations h Plants are drought- or salt tolerant h Seasonal leaf production h Water-storage leaves, roots, and steams hick epidermal layers to reduce h Thick epidermal layers to reduce water loss h Have long taproots that penetrate to the water table h Wide-spreading roots h Have small, spiny leaves (shed less moisture than deciduous leaves) Cactus
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Tropical and temperate deserts Not all deserts are hot and dry! h Tropical deserts, e.g. Sahara (Africa): High temperatures year- round, and very little rain for ahara desert short periods. h Temperate deserts, e.g. Mojave (California): Lower winter temperatures, more precipitation, so sparse vegetation. Sahara desert Mojave desert
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Cold deserts h Cold deserts, e.g. Gobi desert (China): Winters are very cold, summers are warm Precipitation is low.
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Human impacts on deserts h Vegetation grows very slowly with long recovery times, so are vulnerable to human disturbance (e.g. traffic, army tracks) h Overgrazing by livestock h Soils recover slowly
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L12+_28+Sep_+Climate+and+earth_s+major+ecosystem+II+_Lee_ -...

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