Presentation on theme: "Biomes. The axis of rotation is angled 23.5 0 – the latitude that receives the most direct sunlight plus the most hours of sunlight changes throughout."— Presentation transcript:
The axis of rotation is angled 23.5 0 – the latitude that receives the most direct sunlight plus the most hours of sunlight changes throughout the year as Earth orbits the Sun Spring Equinox Spring Equinox (March) – Sun directly overhead – all regions get 12 hours of light + 12 hours of dark – spring begins in Northern Hemisphere; fall in Southern Hemisphere Summer Solstice Summer Solstice (June) – max tilt of Northern Hemisphere toward Sun – longest amount of daylight – summer begins Fall Equinox Fall Equinox (Sept) – opposite of March – day & night equal Winter Solstice Winter Solstice (Dec) – max tilt of Northern Hemisphere away from Sun – shortest daylight – winter begins
Biome – an area characterized by typical plants and animals adapted to the yearly temperature and precipitation Each biome contains many ecosystems whose communities are adapted to local variation in climate, soil, and other environmental factors
Freshwater systems – low levels of dissolved salts Streams and rivers: from mountains to oceans Flow creates different conditions and habitats Headwaters Headwaters: cold, clear, rapidly moving water with high levels of O2 Downstream: slower moving, less O2, warmer temps, more algae and cyanobacteria
Standing water: lakes and ponds Life found in layers – temperature, sunlight, dissolved O2, and nutrient availability changes with depth Littoral zone Littoral zone: shallow area around shore; rooted vegetation Limnetic zone Limnetic zone: open offshore area; too deep for rooted plants; food chain begins with phytoplankton Profundal zone Profundal zone: deep water without light; food chain depends on organisms above Benthic zone Benthic zone: muddy bottom; nourished by decaying organic matter
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