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Chapter 3 The Biosphere 3.1 What is ecology? Ecology: scientific study of interactions among & betwn org & env’t – Ernst Haeckel (1866)-oikos: “house” – Largest “house”: Biosphere: Life Layer: land, water, & atmo, supports life 8 Km atm to 11Km below ocean Levels of Organization Biome: eco w/ same climate & dominate community All org in area w/ env’t Diff pop in same area Grp of same organism (species) in 1 area 1 organism Ecological Research Observation: 1st step in designing experiment/model Experimentation: test hypo – artificial env’t in lab or natural env’t Model: use computer/formula to study – for studies over time or large spacial scale global warming – for ethical reasons Ex: use of mice 3.2 Energy Flow Sunlight: main NRG source for life Autotrophs: (producers) produce food using E from env’t Photosynthesis: plants/algae convert sunlight E into food NRG (Carbs) • 6CO2 + 6H2OC6H12O6 + 6O2 Autotroph (cont) Chemosynthesis: bacteria convert chemical NRG into carb NRG Heterotroph-Consumer: eat food for NRG Herbivore: plant eaters Carnivore: animal eaters Omnivore: eat plants & animals Heterotrophs (cont) Detrivore: feed on remains/dead matter Decomposer: breakdown organic matter Food Chain One-way stepwise flow of NRG Food Web More complex feeding relationships (many food chains) Trophic Levels NRG steps from sun, producers = 1st level l Energy Pyramid Rule of 10%-decrease amt of NRG at each trophic level Biomass Pyramid Amount of living organic tissue/level Pyramid of Numbers # of indiv org at each level 3.3 Cycles of Matter (within/betwn ecosystems) Biogeochemical cycles: forms of matter – connects biology, geological and chemical aspects of the biosphere Continuous Cycle Never stops Water Cycle Precipitation/condensation (dew) Evaportation/transpiration (plant evap) Condensation Preciprain Transpiration (evap from plants) Carbon Cycle • CO2 to producer w/photosyn (sugar) • Consumer eats prod w/C (carbs) • Cellular respir breaks down food – C released back into eco as CO2 Nitrogen Cycle Org require N for Amino Acid for proteins N2 (gas) abundant in atmo N-fixing-bacteria (on legume root) turn N2 into ammonia (useable by plants) Decomposers return N2 to atmo Limiting Nutrient Scarce nutrient, cycles slowly thru sys – Ex: Algae Bloom: growth removes O2 causing other org to die 4.2 What shapes an Ecosystem? Biotic Factors: living (plants/anmls) Abiotic Factors: physical (temp, precip) – Both influence survival, growth, & productivity in habitat (area where org lives) Niche Role in community, “occupation” – Depends on abiotic & biotic factors – One species/niche (competitive exclusion principle) – Includes: food it eats, how it eats, when & how it reproduces Community Interactions 1. Competition: Struggle btw org for limited resources (food, water) Community Interaction 2. Predation: 1 org hunts/kills for food – Predator/Prey Community Interaction 3. Symbiosis: 2 species close together – Mutualism: Both benefit (win-win) – Commensalism: 1 benefits/ other not helped/harmed – Parasitism: 1 (helped) lives in/on another (harmed) – Ex: Aphids & tapeworm Ecological Succession Predicatable changes in ecosystem Primary Succession: w/no soil Pioneer species (1st species): Lichens & mosses break rock to soil 2. Secondary Succession: disturbance w/o removing soil Ex: Fire, tornado, hurricanes