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Transcript
Ecosystems Do Now • What composes an ecosystem? • What are some organisms that can survive in our backyard, but not in other places in the world? • What are some organisms that could not survive in our backyard? • Why? Climate • Many organisms require a specific set of environmental conditions in order to grow. • In an atmosphere, temperature, precipitation, and other environmental factors combine to produce weather and climate • Weather = day to day conditions of Earth’s atmosphere at a particular time and place – Solar energy from sunlight and atmospheric gases effect temperature, weather, and climate • Climate = average conditions of temperature and precipitation in a particular region – Factors of climate include trapped heat, latitude, winds, currents, elevation, and precipitation Greenhouse Effect • Temperature on Earth remains within a livable range because the biosphere has an insulating atmosphere • Carbon dioxide, methane, water vapor, and some other atmospheric gases trap heat energy and maintain Earth’s temperature range • Greenhouse effect = natural situation where a layer of greenhouse gases retain heat energy from sunlight inside the Earth’s atmosphere Latitude • Remember: Earth is a sphere tilted on its axis, so solar energy reaches different parts at different angles, resulting in different heating distributions • Earth has three main climate zones: – Polar = cold areas at the poles of the Earth where the sun’s rays strike Earth at a very low angle – Temperate = between polar and tropic zones, more affected by changing angle of the sun during the year, so ranges from hot to cold depending on the season – Tropical = near the equator receiving more direct sunlight, so the climate mostly warm all year Winds and Currents • The unequal heating of Earth’s surface drives winds and ocean currents, which transport heat throughout the biosphere • Wind forms because warm air near the equator rises and cool air over the poles sinks towards the ground • Ocean currents form because cold water near the poles sinks and flow along the ocean’s bottom and rises in warmer water What shapes an ecosystem? • Remember: Ecosystems are influenced by a combination of biological and physical factors • Biological influences on organisms within an ecosystem = biotic factors – The ecological community ex. Birds, trees, mushrooms, bacteria, frogs, etc. • Physical, or nonliving, factors that shape ecosystems = abiotic factors – Climate, temperature, precipitation, humidity, wind, nutrient availability, soil type, sunlight, water • Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which the organism lives What shapes an ecosystem? • The area where an organism lives including biotic and abiotic factors = habitat (“address”) • The full range of physical and biological conditions in which an organism lives and the way the organism uses those conditions = niche (“occupation”) – Ex. Place in food web, range of temperatures for survival, type of food it eats, how it obtains food, physical environmental condition requirements • The combination of biotic and abiotic factors determines the number of different niches • No two species can share the same niche in the same habitat, however, different species can occupy niches that are very similar, but are still different niches Quick Activity • Describe the biotic and abiotic factors in an ecosystem you know… • Describe the habitat and niche of an organism you know… Community Interactions • When organisms live together in ecological communities, they interact constantly, helping shape the ecosystem • Community interactions, such as competition, predation, and various forms of symbiosis, can powerfully affect an ecosystem 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 – Resource = any necessity of life (water, nutrients, light, food, or space) • Direct competition usually results in a winner and a loser (the loser fails to survive) • The competitive exclusion principle = no two species can occupy the same niche in the same habitat at the same time Predation • An interaction in which one organism captures and feeds on another organism – Predator = organism that does the killing and eating – Prey = organism that is the food Symbiosis • Any relationship in which two species live closely together • Symbiosis = “living together” • The types of symbiosis include: – Mutualism – Commensalism – Parasitism Mutualism • In this relationship both organisms benefit from the association. (+,+) Commensalism • In this relationship one organism is benefited and the other is neither helper nor harmed. (+, 0) • Parasitism • In this relationship, the parasite benefits at the expense of the host. (+, -) Ecological Succession • Ecosystems and communities may appear stable temporarily, but they are always changing due to abrupt or human disturbances or natural fluctuations in the environment • As an ecosystem changes, older inhabitants gradually die out and new organisms move in, causing further changes in the community = ecological succession – Primary succession = occurs on bare rock – Pioneer species = first species to populate an area (lichens) – Secondary succession = a disturbance changes an existing community – Climax community = mature, stable community after specific, predictable stages of succession BIOME • OUR PLANET HAS AMAZING DIVERSITY OF ORGANISMS THAT LIVE IN MANY DIFFERENT ECOSYSTEMS • THE VARIETY OF ECOSYSTEMS ARE CLASSIFIED INTO CATEGORIES CALLED BIOMES • BIOMES = PARTICULAR PHYSICAL ENVIRONMENT THAT CONTAINS CHARACTERISTIC PLANTS AND ANIMALS • THE BIOME IS ALSO THE MOST COMMON CLIMAX ECOSYSTEM THAT WILL FORM IN LARGE CLIMATIC AREAS. • CLIMATE DIAGRAM = GRAPH SUMMARIZING TEMPERATURE AND PRECIPITATION IN SPECIFIC BIOMES TERRESTRIAL BIOMES • TERRESTRIAL BIOMES ARE THOSE BIOMES THAT FORM ON LAND. • THE MAJOR PLANT AND ANIMAL ASSOCIATIONS (BIOTIC FACTORS) ON LAND ARE DETERMINED BY THE MAJOR CLIMATE ZONES OF THE WORLD, MODIFIED BY LOCAL LAND AND WATER CONDITIONS. • CLIMATES WILL VARY AS TO TEMPERATURE, SOLAR RADIATION, AND PRECIPITATION. • THE PRESENCE OR ABSENCE OF WATER IS A MAJOR LIMITING FACTOR FOR TERRESTRIAL BIOMES. MAJOR LAND BIOMES • • • • • • • • • • TROPICAL RAIN FOREST TROPICAL DRY FOREST TROPICAL SAVANNA DESERT TERMPERATE GRASSLAND TEMPERATE WOODLAND AND SHRUBLAND TEMPERATE FOREST NORTHWESTERN CONIFEROUS FOREST BOREAL FOREST (TAIGA) TUNDRA Aquatic Ecosystems • Habitats in water environments • Aquatic ecosystems are determined primarily by the depth, flow, temperature, and chemistry of the overlying water (abiotic factors) Major Aquatic Biomes • Freshwater • Estuaries • Marine water Freshwater ecosystems • Flowing-water ecosystems = rivers, streams, creeks, etc – Organisms are well adapted to the rate of flow – Usually turbulent water at beginning with plenty of oxygen – As water flows downhill, it slows and sediments build up, plants grow, and organisms can make homes • Standing-water ecosystems = lakes and ponds with water circulating within them – Water circulation distributes heat, oxygen, and nutrients – Phytoplankton = single celled algae forming base of aquatic food webs – Zooplankton = planktonic animals that feed on phytoplankton – Plankton = tiny, free-floating or weakly swimming organisms that live in both freshwater and saltwater environments Freshwater wetlands • Freshwater wetlands = water covers soil or it is present near the surface of the soil for part of the year and are usually breeding grounds for insects, fishes, amphibians, and migratory birds – Bogs = form in depressions left by ice that melted thousands of years ago – Marshes = shallow wetlands along rivers and contain cattails – Swamps = water flows slowly and tress and shrubs are present Estuaries • Brackish wetlands formed where rivers meet the sea (mix of fresh and salt water) • Detritus = tiny pieces of organic material that provide food for organisms at the bottom of estuary’s food web (worms, clams, sponges) • Serve as spawning and nursery grounds – Salt marshes = temperate-zone, grasses above tide and seagrasses under water – Mangrove swamps = coastal, tropical zone, mangrove trees Marine ecosystems • Photic zone = well-lit upper layer where photosynthesis can occur allowing algea and other producers to grow – Intertidal zone = organisms are submerged part of the day and exposed to air, sunlight and temperature changes the remainder of the day while battered by waves – Coastal ocean = rich in photosynthetic organisms, plankton, and other organisms including kelp forests and coral reefs • Aphotic zone = permanently dark where chemosynthetic autotrophs survive – Open ocean = aka “oceanic zone” = largest marine zone with low nutrients, small producers, low productivity, fish of all shapes and sizes (swordfish to octopus to dolphins to whales) – Ocean trench = high pressure, frigid temperatures, and total darkness with chemosynthetic producers – Benthic zone = ocean floor contains benthos (sea stars, anemones, marine worms) feeding on detritus that drifts down from the produces near the surface