Transcript Ecology
Energy Flow in Ecosystems and Biogeochemical Cycles Hierarchy of ecology Organism - individual living thing Population- a group of the same species Community – a group of different species Ecosystem – all organisms as well as nonliving things in an area Biome - a major regional or global community of organism - can be as small as the microorganisms living on your skin or as large as the entire biosphere What’s an Ecosystem? An ecosystem consists of all the organisms (biotic) in a community and the environment (abiotic) with which they interact. Biotic - living things plants animals, fungi, bacteria Abiotic - non-living things Moisture, temperature, wind, sunlight, & soil Biodiversity The assortment, or variety, of living things in an ecosystem KEYSTONE Species = a species that has an unusually large effect on its ecosystem Producer Energy flow Chemical cycling Herbivore (primary consumer) Carnivore (secondary consumer) Detritivores (decomposers) Energy flows THROUGH ecosystems – open system Nutrients cycle WITHIN ecosystems – closed system Break down organic materials into simpler cpmpounds Get their energy from non-living sources and make their own food Get their energy by eating living, or once living, resources, such as plants and animals Energy Flow in Ecosystems Almost all energy used in ecosystems comes from the sun From there it flows through a food chain or web and exits the ecosystem in the form of heat, light, kinetic or chemical energy A food chain is a sequence that links species by their feeding relation A food web is a model that shows the complex network of feeding relationships and flow of energy within an ecosystem Types of Consumers Decomposers Herbivores – eat only plants Carnivores – eat only animals Omnivores – eat both plants and animals Detritivores – eat detritis or dead and dying organic matter Decomposers - - detritivores that break down organic matter into simpler compounds (example : fungi) Energy pyramids show the efficiency of energy transfer between trophic levels Generally 10% of energy is transferred Food chains never get beyond 4-5 trophic levels Carnivores that eat secondary consumers Carnivores that eat herbivores Herbivores because they are the first consumer above the producer The first , or bottom, trophic level Biogeochemical Cycle Consumers Producers Detritivores Nutrients available to producers Abiotic reservoir Biogeochemical Cycling of Nutrients The movement of a particular chemical through the biological and geological, or living and non-living parts of an ecosystem. Most ecosystems require a constant inflow of energy from the sun. In terms of matter, such as oxygen and carbon, the Earth is a closed system and it recycles its resources. Water cycle Oxygen cycle Carbon cycle Nitrogen cycle Phosphorous cycle Water Cycle Solar energy drives the global water cycle – Precipitation – Evaporation – Transpiration Water cycles between the land, oceans, and atmosphere Forest destruction and irrigation affect the water cycle Transport over land Solar energy Net movement of water vapor by wind Precipitation over ocean Evaporation from ocean Precipitation over land Evaporation and transpiration from land Percolation through soil Runoff and groundwater Carbon Cycle • Abiotic reservoirs = atmosphere, sedimentary rocks, dissolved carbon in oceans, and fossil fuels – Taken from the atmosphere by photosynthesis – Used to make organic molecules – Decomposed by detritivores – Returned to the atmosphere by cellular respiration CO2 in atmosphere Photosynthesis Cellular respiration Burning of fossil fuels and wood Primary consumers Carbon compounds in water Detritus Decomposition Higher-level consumers Global warming: CO2 lets sunlight through but retains the heat radiated from Earth. Human activities and natural processes add CO2 to the atmosphere, increasing the effect. Photosynthesis removes CO2 from the atmosphere, decreasing the effect. CO2 CO2 in the atmosphere CO2 CO2 Nitrogen Cycle The nitrogen cycle relies heavily on bacteria • Atmospheric N2 is not available to plants – Soil bacteria convert gaseous N2 to usable ammonium (NH4+) and nitrate (NO3-) – Some NH4+ and NO3- are made by chemical reactions in the atmosphere 80% Nitrogen in atmosphere (N2) Nitrogen fixation Assimilation by plants Nitrogen-fixing bacteria in root nodules of legumes Detritivores Decomposition Ammonium (NH4) Nitrogen-fixing soil bacteria Nitrates (NO3–) Nitrifying bacteria Denitrifying bacteria Phosphorus Cycle Depends on the weathering of rock • • Phosphorus and other soil minerals are recycled locally Weathering of rock adds PO43- to soil – Slow process makes amount of phosphorus available to plants low Runoff Sedimentation