Download
1 / 23
230 likes | 347 Vues
Explore the intricate web of interactions in ecosystems, from energy flow to trophic levels and beyond. Learn about physical laws governing energy and the roles of producers, consumers, and decomposers. Discover the significance of primary and net primary production, as well as the factors influencing ecosystem productivity in aquatic and terrestrial environments. Dive into concepts like trophic efficiency, biogeochemical cycles, and the importance of chemical cycling in maintaining ecosystem balance. Delve into the fascinating world of ecosystems and their dynamic processes.
E N D
What is an ecosystem? • All organisms in a community and the abiotic factors they interact with
Physical Laws & Energy • Law of conservation of energy – energy cannot be created or destroyed, only transferred or transformed • 2nd law of thermodynamics – every exchange of energy increases the entropy of the universe • Thus ecosystems need a constant supply of energy
Energy flow in ecosystems • Energy flows through the ecosystem –one way • Sun is primary source of energy
Trophic levels • Autotrophs – primary producers • plants, phytoplankton • Heterotrophs – consumers • Primary consumers – herbivores • Secondary consumers – carnivores that eat herbivores • Tertiary consumers – carnivores that eat other carnivores
Decomposers/Detritivores- get energy from detritus • prokaryotes & fungi are main decomposers • Decomposition connects all trophic levels • http://www.countrysideinfo.co.uk/rabbita.htm • http://vimeo.com/21216124
Sun Key Chemical cycling Energy flow Heat Primary producers Primaryconsumers Detritus Microorganismsand otherdetritivores Secondary andtertiary consumers
Primary production • Most ecosystems - primary production is the amount of light energy converted to chemical energy by autotrophs during a given time period • In a few ecosystems, chemoautotrophs are the primary producers
GPP vs. NPP • Gross primary production – total primary production • Net primary production: • = GPP minus energy used by primary producers for respiration • On average NPP is ½ of GPP • This is the amount of energy available to consumers
Global net primary production Net primary production(kg carbon/m2yr) 3 2 1 0
Primary production in Aquatic systems • Factors: • Light limitation • Nutrient limitation Commonly nitrogen & phosphorous • Eutrophication • Process where bodies of water receive too many nutrients, which results in excessive plant growth, reducing oxygen concentration & water clarity
Primary production in Terrestrial ecosystems • Factors • Temperature • Moisture • Nutrients
Plant adaptations for nutrients • Symbiotic relationships: • Nitrogen fixing bacteria – • Convert N2 to NH3 • Rhizobium forms nodules on roots of legumes • Mycorrhizae - • Host plant provides fungus with sugar • Fungus increases surface area for water uptake, and supplies plant with minerals absorbed from soil
Secondary production The amount of chemical energy from food that is converted to a consumer’s biomass
Trophic efficiency • 10% rule • Only 10% of energy available at one trophic level is transferred to the next trophic level • 90% of energy is not transferred: • Not eaten, lost through respiration, contained in feces • http://science.howstuffworks.com/life/27995-assignment-discovery-energy-flow-video.htm
Biogeochemical Cycles Matter gets recycled
