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FJC Environmental Biology 105: World Biomes Lecture Seasons Suns rays hit N hemisphere: (1) obliquely for ½ of year (Autumn/Winter: Sep-Mar) (2) more directly for ½ of year (Spring/Summer: Mar-Sep) Same in S. Hemis., but reversed At poles summer solstice (June 21 in North) = 24 hrs. day Poles Winter Solstice (21 Dec) = 24 hr. Night Earth is tilted on its axis 23.5˚ As Earth rotates around sun (365 days) One pole or other is closer to sun: Seasons Tilt toward sun at Summer Solstice (June 21-North) At poles = 24 hrs. day Tilt away from sun at Winter Solstice (21 Dec – N.) At Poles = 24 hr. Night Equator has little seasonal variation in temp. Coriolis Effect Eastward rotation of Earth on its axis 15°/hr Deflects moving objects (air, water) away from initial course Earth spins faster at Equator (0°): 1700 km/hr Than at higher latitudes: 1260 km/h at 43° WORLD BIOMES ARCTIC Encircles polar seas Similar to Antarctic (arctic larger) Portion is permanent ice Very cold Winter (record -96˚F/-71˚C – Siberia) Very dry (1-8”, 3-20 cm/year) Day Length: 22 hr dark (winter), 22 hr light (summer) Polar Bear, Orca, Walrus, Beluga Whale, N. Fur Seal, Sea lion TUNDRA Tundra: “Treeless Plain” South of Arctic circle Alaska, Canada, Russia, Norway, Sweden, Finland, Greenland Permafrost: Permanently frozen sub-soil Consequences: physical barrier to roots Low temps slow down decomposition, promotes peat buildup Retards water percolation = boggy soil Very slow plant growth Taiga (Boreal Forest) Coniferous forests (evergreens) Pine, spruce, fir + moss, lichens Largest Biome (Canada, N. Europe, Asia) Warm, rainy summer (Avg. =70F, 12-33” rain/yr.) COLD winter (Avg. 30F, low as – 65F) Bears, Moose, Wolves, Canadian Lynx Temperate Deciduous Forests Trees drop leaves in Winter (Deciduous) Many plants go dormant 4 Distinct seasons Mod. Temp (Avg. =50F), winter freeze Mod. Rain (30-60”/75-150 cm) Maple, Birch, White Oak, Elm Shrubs, ferns, moss, lichen = lower canopy Sm. herbivorous mammals, amphibians & reptiles Cool Temperate Forests (Maritime) Temperate Coniferous Rain Forests Frequently listed with Taiga Pacific NW USA, SW Canada (Vancouver, Victoria) Mild Temps. year round (Ocean influences) High Rainfall (60-150” per year) Redwood, Spruce, Cedar, Douglas Fir Grasslands Eurasian Steppe, Prairie (N. America), Pampas (S. America) Fire limits trees, grasses re-sprout Largely altered for cultivation Tall grass(wet), short grass (dry), flowering plants Large Herbivores: Bison, Antelope Prairie Dogs, rabbits, mice = Hawks, Falcons Badgers, Foxes, Coyote Savanna Grasslands w/ trees & shrubs Dry Tropical Forests/Tropical Grasslands Warm all year (68-86°F) 2 Seasons: Rainy (Summer), Dry (Winter) 4” (Dry Season), 15-25” (Wet Season) Africa: Acacia, Elephant, Lion, Hyena, Zebra, Giraffe Australia: Eucalyptus, Kangaroos, Koalas, Emus S. America: Capybara, Marsh Deer Tropical Rain Forest Tropical Rain Forest Warm all yr. (68-88%) Rainy (75-260”/yr. = 190-660 cm/yr) 50% of all animals on Earth Produces 40% of Oxygen 25% of all medicine (1,400 potential Cancer drugs) 4 Vegetation layers: Emergent Trees, Upper Canopy, Understory, Forest Floor Most animals live in Upper Canopy Tropical Rain Forest Few Soil Nutrients Rain washes away Rapid Decay from heat & humidity Many Decomposers: Fungi, Ants, Termites Low light in understory Plants adaptations: shallow roots; epiphytes; vines; large, dark leaves Tropical Rain Forest Issues Only cover 6% of Earth surface Slash & Burn for Agriculture: Removes most nutrients 99% nutrients held in tree roots Few years before soil is depleted of all nutrients Farms must be abandoned Decades/centuries to re-grow Desert Evaporation > Precipitation (≤ 10 in.) Temperate: Furthest N. & Coldest Great Basin (NV,UT,ID); Gobi (Cent. Asia) Subtropical: 15-30° N & S, Warmer S.W. USA / N. Mexico (Sonora), N Africa (Sahara), Australia, Chile / Peru Little Cloud Cover = Hot, dry days & Cold nights Soils: Few organics, clay, hardpan, sand Desert Adaptations Plants: Tap or shallow roots Succulents Small leaves Light-colored leaves No Leaves (Thorns) Waxy cuticle Dormant in extreme seasons Animals: Moisture from food Nocturnal Burrows Small size = decreases surface area Shrublands 5 Places on Earth (30-40 degrees N & S of Equator) (1) S. Calif., (2) Chile, (3) SW Australia, (4)S. Africa, (5)SW Europe—NW. Africa West side of continents, cold ocean currents Winter Rain, Summer Dry (High Evaporation, windy) Plants of 5 regions have similar adaptations & appearance = Convergence Shrublands Plant types: Shrubs drought tolerant trees Spring annuals & grasses Plant adaptations (similar to deserts): Small, waxy, or succulent leaves Many have pale colored leaves Compact size Fire South African Fynbos, Mediterranean (Europe, N. Africa) Coastal Sage Scrub, Chaparral (S. California) Chaparral characteristics: South facing slopes Dark leaves Tough leaves Waxy leaves Fire adapted Coastal Sage Scrub Characteristics: North facing slopes Light colored leaves (gray) Soft leaves Oily leaves Prickly pear cactus Fire adapted Fire Adapted Ecosystems 10-40+ year fire cycle Need for fire: Seed germination Remove litter (slow decomposition) Adds organic nutrients to soil Plant adaptations: Oils promote fire bark protection new shoots from base roots or crowns (Root-crown sprouting) Seed coats stimulate some plants to increase and/or flower Oak Woodlands Associated with Chaparral & Coastal Sage Scrub Foothills, valleys, riparian areas Deeper soil, more moisture, less wind Other woodland species: Poison Oak, bunch grass Near creeks (riparian): Western Sycamore, White Alder, California Walnut, Fremont’s Cottonwood Oak Woodlands Southern Californian Urban Sprawl: 90% of coastal sage scrub has been lost to development (only 10% left) Aquatic Biomes Aquatic ecosystems are linked Lakes flow to rivers then estuaries then oceans Rivers bring nutrients/minerals from land to sea Seawater & freshwater evaporates & eventually falls as rain over all aquatic zones Salt is left behind Aquatic Biomes - Freshwater Lakes & Ponds Inland depressions of standing water Arise from: Glacial abrasion volcano craters silt deposition in stream beds Earth’s shifting crust Dams = artificial lakes by damming rivers for power, irrigation, water storage Lakes & Ponds Two types: Oligotrophic (nutrient –poor) Eutrophic (nutrient- rich) Agricultural & urban run-off = algae blooms, low dissolved O2, fish kills Eutrophication Stratified in summer & winter: Warm layer at top in summer Cold layer & ice at top in winter (prevents freezing of whole lake) Rivers & Streams Continuously moving water Begin as: Outlets of lakes/ponds Seep from shallow groundwater Snowmelt (mountains) 2 Types: Perennial (wet year round) Intermittent (seasonally dry) Typical of arid zones Rivers & Streams Change direction during high velocity events Humans extensively develop floodplains Most modified by Dams or channelized with concrete Damming the Yangtze River (China) Hydroelectric power for industrial development Protect millions from floods BUT: Relocation of 1.9 million people Destruction of River ecosystem Extinction of Chinese River Dolphin Submerge ancient archeological treasures (2,000-7,000 yrs.) Siltation = poor water quality, dam may fail in 50 years Aquatic Biomes - Marine Oceans 4 main bodies: Pacific, Atlantic, Indian, Arctic Oceans Divided into zones: Pelagic (Open ocean) Benthic (in or on soil) Littoral (Shoreline) Pelagic: Open Ocean Organisms swim or float Phytoplankton = most of Earth’s oxygen (upwelling) Food web: Phytoplankton zooplankton Anchovy mackerel dolphin Dark below ~120 m Many bioluminescent animals Benthic: Ocean bottom Organisms live in or on soil: Detritivores: feed on marine snow (dead organisms from above) Continental shelf/slope: Kelp, seastars, flat fish brittlestars, tube worms Benthic Abyssal zone: deep sea plain Brittle stars, sea cucumbers Deep sea trenches & Hydrothermal vents: Hot wate Chemical reaction sulfate + H2O = H2S Chemosynthesis: Bacteria convert H2S into energy Need no light These bacteria live in Tube Worm tissues Littoral (Intertidal): Shoreline (Rocky or Sandy) Rocky Shore Stressful habitat Wave stress, alternate dry & wet periods, sun (UV) exposure, rocks Zonation: Upper intertidal: closest to land, mostly dry. Periwinkle snails, Barnacles Mid-intertidal: Dry ½ of time, wet ½ time. Algae, limpets, crabs, mussels, purple sea urchin, Sea anemones Lower intertidal: furthest from shore, mostly submerged. Algae, sea stars, red sea urchin, sea hare, sea cucumber Sandy Shores Difficult place to live Abrasive sand Tides = wave stress, wet/dry fluctuation Animals live on sand (epifauna) or in sand (infauna) Sand crabs (ampipods), worms (nematodes) burrow in sand & eat detritus Clams (bivalves) breathe thru siphon Shorebirds feed & nest Marine Biomes - Estuaries Swamps: Wetland with trees Present in Salt & Freshwater ecosystems Mangroves (Tropical) Everglades - Florida (Tropical/subtropical) Salt Marshes: Protected coastlines (mid-high latitudes) No Trees Grasses, succulents, small shrubs Halophyte plants (“salt loving”) Adaptations: exude salt from tips, shunt salt to old leaves & drop old leaves Pacific Flyway: birds migrate between Northern breeding grounds (summer) & southern winter/feeding grounds Estuary & Wetland Issues Unappreciated Most have been filled in: Development, harbors, power plants, agriculture, roads California has greatest wetland losses 90% total wetlands, 75% salt marsh Restoration: Return wetland to “natural state”, former function Everglade Restoration: Largest restoration effort on Earth Interagency effort: Federal & State, Universities, environmental groups