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- factors that limit primary production in terrestrial systems
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-climatic factors (temp, precipitation)
-nutrients (nitrogen, phosphorus, calcium, potassium)
- factors that limit primary production in aquatic systems
- -nutrient availability (phosphorus, nitrogen)
- primary production varies with succession
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-photosynthetic biomass, plant diversity, and nutrient supply vary
-highest NPP tends to be at intermediate stages of succession - primary production varies with latitude
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-highest rates are in tropics
-due to growing season and precipitation - primary production varies with biomes
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-highest rates are in tropics and savannas
-lowest in tundras and deserts
-due in part to leaf area index and growing season - primary production varies with upwelling
- -highest rates in oceans are in zones of upwelling
- NPP and biodiversity on local scale
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-among ponds
-diversity peaks at intermediate levels of NPP - NPP and biodiversity on regional scale
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-among watersheds
-diversity is linearly correlated with NPP - how eutrophication can lead to die-offs
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-nutrient input
-increased primary production
-zooplankton reproduce
-more zooplankton than can be eaten
-zooplankton bodies decomposed by bacteria
-bacteria reproduce
-bacteria use up all available oxygen
-mass die-offs - what do trophic pyramids represent?
- -the amount of biomass or energy
- 3 components of ecological efficiency
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-consumption
-assimilation
-production - how the 2nd law of thermodynamics influences energy flow
- -energy is lost during transfer due to an increase in entropy (disorder)
- why biomass trends are different in terrestrial vs aquatic systems
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-inverse of each other
-most primary production in aquatic systems take place in phytoplankton, which are quickly consumed - two general ways that nutrients are made available to living organisms
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-weathering
-atmospheric conversion - phosphorus
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-component of ATP, RNA, DNA
-not very abundant
-slowly released into ecosystem through rock weathering
-mean residence time: thousands of years - nitrogen
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-component of amino acids, nucleic acids, chlorophyll, hemoglobin
-large amount in atmosphere
-mean residence time: 625 years - carbon
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-10 million compounds contain carbon
-moves from land to atmosphere (photosynthesis-atmosphere to organism, respiration-organisms to atmosphere)
-increased atmospheric carbon leads to climate change
-residence time: 1- millions of years - what is necessary for fossil fuels to form?
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-heat
-pressure
-time - ways oil spills can affect ecosystems
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-harms surface organisms
-crude oil up to 40% methane
-oil and dispersants are toxic
-small particles can clog gills or enter food chain
-tar balls - how disturbance can affect nutrient cycles
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-increase nutrient loss
-reduce primary production
-loss of biomass speeds mineralization
-increased rainfall washes nutrients away - how bioturbation affects nutrient cycles
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-caused by benthic or burrowing organisms
-ex: earthworms - primary succession
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-occurs in newly formed habitats
-after a dramatic, large scale disturbance
-generally slow - secondary succession
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-after any type of disturbance that is not catastrophic
-occur quickly - types of organisms in pioneer vs climax communities
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-pioneer: r-selected
-climax: k-selected - early views on succession
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-there was a particular sequence and process of primary production
-succession was analogous to an organism which undergoes a life cycle in a deterministic manner
-both organisms and the environment shape succession - 3 general mechanisms for succession
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-facilitation model
-inhibition model
-tolerance model - facilitation model
- -early species modify environment to aid colonization of later species
- inhibition model
- -early species may modify environment that hinders colonization of later species
- tolerance model
- -later species are not affected by earlier species
- intermediate disturbance hypothesis
- -community diversity should be greatest at intermediate levels of disturbance
- relationship between species richness and area
- -species richness increases with increased area sampled
- equilibrium theory of island biogeography
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-the number of species on an island is a balance between immigration and extinction
-closer island have higher immigration
-larger islands have lower extinction rates - lower extinction rates
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-primary producers
-smaller organisms - higher extinction rates
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-species at higher trophic levels
-species with mutualistic partners
-larger organisms - good dispersers
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-birds
-plants with wind dispersal seeds
-marine mammals
-large mammals - bad dispersers***
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-amphibians
-plants with heavy seeds
-freshwater fish - island formations
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-continental islands
-volcanic islands
-sediment accumulation
-landslides - species on continental vs volcanic islands
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-continental can start with same # of species as mainland
-volcanic has to gain species over time - components of landscape hetergeneity
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-landscape composition
-landscape structure - factors that can shape landscape structure and composition
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-geological processes
-climate
-nutrient and water availability
-fire
-organisms - 3 ways habitat fragmentation can affect landscapes
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-decreases habitat area
-isolates populations
-alters conditions through increase in habitat edges - benefits and potential problems with corridors
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-not all species will use a given corridor
-large edge effects in corridors
-can contain many predators
-allow invasive species to disperse
-allow disease to spread
-can be used as an excuse to destroy more habitat
-can be expensive - components of global ecology that occur naturally
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-el nino southern oscillation
-pacific decadal oscillation
-global nutrient cycles
-dispersal of organisms - 3 major global changes
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-changes in the nitrogen cycle
-changes in landscape
-changes in atmospheric CO2 - habitat loss vs alteration vs fragmentation
- -alteration=pollution, invasive species
- small factors that can change the atmosphere
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-volcanic eruption
-forest fire - big factors that can change the atmosphere
- -oxygen began building up in the atmosphere