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Transcript
UNIT 2: ECOLOGY THE BIOSPHERE Apollo 8 December 24, 1968 “Ecology”? = The study of interactions among organisms and between organisms and their environment Levels of Ecology: Populations Biosphere Put these in order (smallest largest) Ecosystems Biomes Species Communities Biosphere 8km Up 11km Down At the core of every organism’s interaction with the environment is its need for energy to power life’s processes The flow of energy through an ecosystem is one of the most important factors that determines the system’s capacity to sustain life Main Source “Autotrophs” “Heterotrophs” Autotrophs/ Producers (Photosynthetic and Chemosynthetic) Heterotrophs/Consumers (Herb-/Carn-/Omn-ivores and Decomposers) Energy flows through an ecosystem in one direction, Sun or Inorganic compounds Autotrophs (producers) Heterotrophs (consumers) Food Chains = a series of steps in which organisms transfer energy by eating and being eaten Trophic Levels = each step in a food chain or food web Food Webs = links all the food chains in an ecosystem together Producers? First Order/Primary Consumers? Second Order/Secondary Consumers? Third Order/Tertiary Consumers? Fourth Order/Quaternary Consumers? Ecological Pyramid = a diagram that shows the relative amounts of energy or matter contained within each trophic level in a food chain or food web Energy Pyramids = represents the amount of energy that is transferred from one trophic level to the next Only about 10% of the energy available within one trophic level is transferred to the next What happens to the rest? Life Processes and Heat Biomass Pyramids = represent the amount of potential food that is available for each trophic level in an ecosystem Biomass is usually expressed in terms of grams of organic (living) matter per unit area Pyramid of Numbers = represents the numbers of individual organisms at each trophic level in an ecosystem Cycles Don’t just need energy! What else is needed? More than 95% of the body is made up of just four elements: oxygen, carbon, hydrogen, and nitrogen Biogeochemical Cycles Organisms don’t “use-up” matter, they “transform” it The Water Cycle Nutrient Cycles The Carbon Cycle The Nitrogen Cycle Proteins 78% Nitrogen Fixation The Phosphorous Cycle DNA/ RNA/ ATP Doesn’t enter the atmosphere Primary Productivity = the rate at which organic matter is created by producers Limiting Nutrient = a nutrient that is scarce or cycle slowly Oceans = Nitrogen UNIT 2: ECOLOGY ECOSYSTEMS AND COMMUNITIES 1. 2. 3. 4. The Role of the Climate What Shapes an Ecosystem? Biomes Aquatic Ecosystems 1. THE ROLE OF CLIMATE • • • • What is Climate? The Greenhouse Effect The Effect of Latitude on Climate Heat Transport in the Biosphere What is Climate? Weather = the day-to-day condition of Earth’s atmosphere at a particular time and place. Climate = the average, year-after-year conditions of temperature and precipitation in a particular region. What factors affect the climate? The Greenhouse Effect Greenhouse Effect = the natural situation in which heat is retained by greenhouse gases (warming effect) Carbon dioxide, methane, water vapor, and a few other atmospheric gases Earth would be 30o C cooler than it is today if these gases weren’t present The Effect of Latitude on Climate Earth’s 23.5o tilt on its axis causes different parts of Earth to receive different angles of solar radiation This results in a difference in heat distribution with latitude Three Main Climate Zones Polar Zones = between 66.5o and 90o North and South latitudes Temperate Zones = sit between the polar and tropical zones Tropical Zones = between 23.5o North and 23.5o South of the Equator Polar Zones Low Angle Sunlight Cold Temperate Zones Seasonal Changing Angle Tropical Zones Direct Angle Constant Heat Transport in the Biosphere The unequal heating of Earth’s surface drives winds and ocean currents, which transport heat throughout the biosphere Winds Warm “Rises” Pole-ward Ocean Currents Cold “Sinks” Equator-ward Mountains and the ”Rain Shadow” Effect Ocean Currents contribute for same reasons 2. WHAT SHAPES AN ECOSYSTEM? • • • • Biotic and Abiotic Factors The Niche Community Interactions Ecological Succession Biotic and Abiotic Factors Biotic Factors = the biological influences on organisms within an ecosystem Abiotic Factors = physical, or nonliving factors that shape ecosystems Determine the survival and growth of an organisms and the productivity of the ecosystem in which the organism lives Habitat = the area where an organism lives (includes both biotic and abiotic factors) The Niche Niche = the full range of physical and biological conditions in which an organism lives and the way in which the organism uses those conditions Community Interactions Community interactions can powerfully affect an ecosystem 1. Competition Competition occurs when organisms of the same or different species attempt to use an ecological “resource” in the same place at the same time Often results in a winner and a loser (fails to survive) Competitive Exclusion Principle = no two species can occupy the same niche in the same habitat at the same time CEP is a fundamental rule in ecology 2. Predation Predation = an interaction in which one organism captures and feeds on another organism (predator/ prey) 3. Symbiosis Symbiosis = any relationship in which two species live closely together (“living together”) A. Mutualism B. Commensalism C. Parasitism A. Mutualism = both species benefit from the relationship B. Commensalism = one member benefits and the other is neither helped nor harmed C. Parasitism = one organism lives on or inside another organism (the host) and harms it Ecological Succession Ecosystems and communities are always changing (abruptly or gradually) in response to natural or human disturbances Ecological Succession = this series of predictable changes that occurs in a community over time Mt. St. Helens May 1980 Lowered to 8,363 ft Summit = 9,677 ft As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community Primary Succession = succession (on land) that occurs on surfaces where no soil exists (volcanic eruptions, glaciers, etc.) Pioneer Species = the first species to populate the area Lichen = a symbiotic relationship between a fungus and an algae (protist) Enchanted Rock (Fredericksburg) Secondary Succession = succession that occurs when a disturbance of some kind changes an existing community without removing the soil Succession can even occur at the bottom of the oceans 3. BIOMES • Biomes and Climate • The Major Biomes • Other Land Areas Ecologists group Earth’s diverse environments into biomes Biome = a complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular assemblages of plants and animals World’s Major Biomes: -Tropical Rain Forest -Tropical Dry Forest -Tropical Savanna -Desert -Temperate Grassland -Temperate Woodland and Shrubland -Temperate Forest -Northwestern Coniferous Forest -Boreal Forest -Tundra Each of these biomes is defined by a unique set of abiotic factors – particularly climate- and a characteristic assemblage of plants and animals Adaptations Tolerance The climate of a region is an important factor in determining which organisms can survive there Microclimate = the climate in a small area that differs from the climate around it Some areas of land on Earth do not fall neatly into the major biome categories Mountain Ranges Abiotic and biotic conditions vary with elevation Polar Ice Caps North Polar Region (thinner ice) South Polar Region (thicker ice) 4. AQUATIC ECOSYSTEMS Impacted by: Depth Flow Temp Chemistry of Water Freshwater Ecosystems 3% of World’s Surface Water Standing-Water Flowing-Water Flowing-Water Ecosystems: (Rivers, Steams, Creeks, and Brooks) Typically originate in mountains or hills, often springing from an underground water source Plenty of dissolved oxygen but little plant life Farther downstream, the water may meander more slowly through flat areas As the water flows downhill, sediments build up and enable plants to establish themselves Standing-Water Ecosystems: Lakes and ponds In addition to the net flow of water in and out of these systems, there is usually water circulating (turning-over) within them This circulation helps to distribute heat, oxygen, and nutrients Phytoplankton = single-celled algae supported by nutrients in the water Plankton = tiny, free-floating or weakly swimming organisms that live in both fresh/saltwater Zooplankton = planktonic animals that feed on the phytoplankton Freshwater Wetlands: Wetland = an ecosystem in which water either covers the soil or is present at or near the surface of the soil for at least part of the year “Biodiversity” Bog Marsh Swamp Estuaries Estuaries = are wetlands formed where rivers meet the sea fresh water and salt water (brackish) Affected by the ocean tides High Productivity Detritus = is made up of tiny pieces of organic material that provide food for organisms at the base of the estuary’s food web “Coastal Zone” “Open Ocean” Photosynthesis (200 meters) Chemosynthesis Coral Reefs Exists in warm, shallow water of tropical coastal oceans Among the most diverse and productive environments on Earth Named for the coral animals whose hard, calcium carbonate skeletons make up their primary structure (Coral) Symbiotic relationship with Algae Algae: Photosynthesis Coral: Waste