Lecture 3 Notes Ecosystems Biomes Ecology and biotic Study of how organisms interact with their environment both abiotic o Abiotic non living physical chemical o Biotic living other organisms Goal is understand the distribution and abundance of organisms Abiotic Factors Terrestrial enviroments defined by climate Aquatic habitats are defined by nutrient availability water depth water movement Tropics are warm poles are cold based on amount of sunlight per unit area Poles have a low angle of incoming sunlight Equator sunlight directly over head Hadley Cells Giant global air circulating cells o Profoundly influence regional precipitation patterns Tropical regions with rising warm air tend to be wetter Regions with descending cool dry air tend to be dry Notice major deserts aprox 30 degrees north or south Hadley Earth s rotation imposes predictable directionality on Hadley cell cells derived wind systems Giant Subtropical gyres light red circular surface currents Move vast amounts of heat from equatorial latitudes to high latitudes Influence temperature on much of planets surface Seasonality Regular annual fluctuations in temperature precipitation or both Seasons result form earth s 23 5 degree tilt o Til changes throughout the earths trip around the earth Summer Solstice solar radiation most intense at 30 degrees N Spring and Fall equnioxes sun directly above equator Winter Solstice 30 degrees S Mountain ranges can profoundly impact local precipitation Great lakes regional weather modifiers Collectively terrestrial biomes plus aquatic enviroments make up Types of terrestrial ecosystems Characterized by specific temp and precipitation patterns Found in equatorial regions tempature and rainfall are high annual High species diversity Extremely high productivity amount of carbon fixed by photosynthesis per unit area per year High aboveground biomass total mass of living plants excluding BIOMES BIOSPHERE Tropical Wet Forest variation is low roots Subtropical Desert High average annual tempatures moderate variation in tempature Very low precipitation Productivity very low Species adapt by growing a low rate year round or growing rapidly in response to rainfall Temperate Grassland Prairies or steppes Temperatures are moderate Precipitation is low A moderate annual temperature variation dictates well defined growing season Grasses r dominant plants Productivity is generally low grassland soils are often highly fertile Temperate Forest growing Experience period of time temp fall below freezing plant life stop Precipitation is moderately high and constant through year Dominated by deciduous trees Species diversity moderate Productivity intermediate Boreal Forest Artic Tundra Very low temperatures High variation in temperature Very low annual precipitation Treeless except small woody shrubs Low plant species diversity Low productivity Low above ground biomass Tundra soils are perenninally frozen state known as permafrost LOOK AT CHART IN LECTURE SLIDES Aquatic Habitats Defined by nutrient availability water depth and water movement Water Depth o Light penetrates farther in freshwater vs seawater o Intensity of light declines with water depth o Most of the world s ocean exists in complete darkness o Photosynthetic activity is restricted to the uppermost layers photic zone less than 100 meters Photic zone vs aphotic zone o Almost all of photic zone is over deep water o Marine plants must stay in top 10 s of meters to Manage this by being microscopic and predominately photosynthesize single celled o Phytoplankton 1 of plants photosynetic biomass 45 of planet s photosynthesis o growth on the west coast is stronger vs east coast sturing of nutrients form the bottom to the top is caused