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Biol 208 – Devito 1) 2) 3) 4) Lecture note taking & study methods Prior to lecture 1) Look at the schedule provided at beginning of term Read (with out taking notes) the pages suggested to familiarize yourself with the topic 2) Use the outline provided at start of class as a guide During lecture, make very cryptic / short hand notes 1) Write summaries of the discussion, not every word 2) The notes will be provided later After class 1) That evening, read your notes, check figures in text 2) End off week, merge web notes with your lecture notes 3) Read text to fill in holes, clarify Exam 1) 7 days before, spend 1-1.5 hr per day on one subject. 2) Arrange & organize notes. 3) Read full notes once a day 4) Day 3 start asking your self questions, 1) make a summary/ cheat sheet (outlines are provided) – key topics, words etc – consult this and determine if you know these, if not go back to full notes Unit 4: Landscape and Ecosystem Ecology ECOSYSTEMS –Biogeochemistry, energy & organisms Ecosystem perspective Æconsequence of E & nutrient interactions A. ORGANISMS in ecosystems p29-30, p407-408, 410-13 A.1) Trophic classification Food Chain A.1.1)Trophic Levels or Components a) b) c) Producers (1o production) Consumers (2o production) Decomposers (3o production), A.2) Controls of Trophic Level Biomass A.2.1) Top Down Controls a) b) Keystone Spp Trophic Cascade A.2.2) Bottom Up Controls A.2.3) Limits to Global 1o Production Biol 208 – Devito Unit 4: Landscape and Ecosystem Ecology • Until now concerned only with organism & interaction in communities • lets start considering surrounding environment & landscape Biol 208 – Devito Unit 4: Landscape and Ecosystem Ecology ECOSYSTEMS -merging food webs (Ch 21), ecosystems energy (Ch 6 & 8), & nutrient (Ch 7) cycling - concepts developed by: C. Elton (1920-Foodweb), A.G. Tansley - Consider community with their abiotic environment - Hierarchical & functional relationships of communities w geographical & functional relationship to their environment. A.J. Lotka , R. Lindeman (1942) - ecosystem fundamental unit of ecology= food-web & energy transfer E.P Odum (1953) – ecosystems as energy flow diagrams = Ecosystem Ecology -cycling of matter & passage of energy basis for characterizing ecosystem structure & function 1 Biol 208 – Devito ECOSYSTEMS Biol 208 – Devito ECOSYSTEMS A. ORGANISMS in ecosystems 3 Main Components of Ecosystems Biogeochemistry: nutrient cycling, raw materials for ecosystem Energy: needed to convert nutrients into life forms Organisms: consequence of E & nutrient interactions A. ORGANISMS in ecosystems A.1) Trophic classification - Food Chain –cont’d “abstract model” to generalize ecosystem function – systems approach Meadow ecosystem functions same as Hawk Æ foxÆ rabbit Æ grass Pond ecosystem lg Fish Æ sm fish Æ zooplanktonÆ algae p29-30, p407-408, 410-13 Ecosystem perspective Æconsequence of E & nutrient interactions A.1) Trophic classification Food Chain -Summary of feeding interaction w/in community - basic description of community structure, - also transfer of energy & masses of elements Meadow ecosystem Hawk Æ foxÆ rabbit Æ grass A.1) Trophic classification - Food Webs Food Webs more complex than linear chains: -complexity increases with increase community diversity •2 very diff communities with diff species, •function same manner with respect to interactions, matter & energy flows •Replace fox, replace zooplankton? 2 A.1) Trophic classification - Food Web A.1) Trophic classification - Food Chain –cont’d -simplify complexity, focus on important (strong) interactions, -trophic levels or components African Savannah Ecosystem -energy flow A.1.1)Trophic Levels or Components a) Producers (1o production) -they are autotrophs “self feeders”, produce their own energy source -basis of live on earth, & all food chains Photoautotrophs: derive energy via photosynthesis in chloroplasts, reduce inorganic sources using sun’s solar radiation. -most ecosystems of the world A.1) Trophic classification - Food Chain –cont’d A.1.1)Trophic Levels or Components A.1.1)Trophic Levels or Components Heterotrophs: derive energy from produced organic matter, they consume other organisms a) Producers (1o Production) Chemoautotrophs: some bacteria use energy stored in chemical bonds within the earth system b)Consumers (2o production) i) Grazers/herbivores: eat producers ii) 1o Carnivore: eats grazer ie bacteria Thiobacillus uses Sulfur compounds as energy source in deep sea vents. iii) 2o carnivore: carnivores that eat carnivores Deep Sea vent ecosystem 3 A.1) Trophic classification - Food Chain –cont’d A.1.1)Trophic Levels or Components c) Decomposers (3o production), - transformers, reducers -take dead prod & consumers break them down to elementary nutrients -make nutrients available for re-cycling *important A.ORGANISMS in ecosystems A.2) Controls of Trophic Level Biomass - unit 2 and 3, learned that predators can depress the populations of their prey dramatically A.2.1) Top Down Controls a) Keystone Spp -often major predators, feeding activities of few: - have dominant influence on community structure, - disproportionately large influence rel. to biomass A.2.1) Top Down Controls a) Trophic Cascade example River food webs, -local controls on biomass of trophic levels Determine the number of trophic levels – 4 levels in this ecosystem 2o Carnivore 1o Carnivore Study by Power (1990) Eel River, California -What is causing major algae growth (eutrophication) of some trout streams? Herbivore 1o producer 4 Power (1990) Eel River, California Enclosure experiment A & B Steelhead Æ Stickleback Æ Chironomid Æ diatoms/algae Roach Roach fry Cladophora Pred Insect Nostoc A. Remove Steelhead etc. LOW# Æ algae bloom, HIGH# due to pred less grazing A.2.2) Bottom Up Controls • the size of the trophic level is determined by the rate of 1O production of food both Top-down & bottom up occur in ecosystems - more pronounced in aquatic systems, less so in terrestrial systems a) Bottom Up Influences Zooplankton biomass HIGH # Æ algae #’s kept LOW eat algae A.2) Controls of Trophic Level Biomass • - Herbivory/Predation can limit 1o and 2o production -Can use some keystone carnivore spp to manage 1o production B. Control (with pred fish) High # fish Æ LOW # Æ Predators due to pred -Alternating changes in biomass with each trophic level A.2.2) Bottom Up Controls •increased primary production tends to augment all overlying trophic levels Algae Biomass ug/L •global/regional scales 1o production tends to limit 2o production b) Top Down Influences Zooplankton biomass Low # fish Æ HIGH # Æ No predation Cascading Hypothesis •Top down increases variability in bottom-up relationship Algae Biomass ug/L 5 A.2.3) Global 1o Production -virtually all energy originates from solar radiation A.2) Controls of Trophic Level Biomass A.2.3) Limits to Global 1o Production -virtually all energy originates from solar radiation A.2) Controls of Trophic Level Biomass A.2.3) Limits to Global 1o Production a) Terrestrial 1o production: -limited by solar input (E) and moisture (Climate) - nutrients only control at regional & local scales i) Latitutude, Solar Input -Solar Energy greatest at equator, decreases to poles - thus, generally greater 1o production & biomass at equator than the poles -even though nutrients greater at the poles ii) Moisture - low in deserts (about 30o latitude) b) Marine 1o Production, - highest at mid latitudes (40-60o ) - Ocean Currents, nutrient regeneration -energy/light limited at poles 6 Geographical variations initial ecosystem production •Terrestrial 1o product’n > marine (even with less area) •Greatest 1o Production on Land or wetland in humid tropics •Lets follow how the energy follow along trophic levels 7