ES100_Final Study Guide

ES100_Final Study Guide - Lecture 20 Nutrient Cycling in...

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Unformatted text preview: Lecture 20 Nutrient Cycling in Ecosystems and Anthropogenic Disruptions What determines Productivity? What determines Diversity? Ecosystem Ecology o Ecosystema biological community together with the abiotic environment in which it is set Abiotic + biotic =integrated system Defined boundaries Many scales (global, watershed, single community type) o Higher level of organization than communities Different processes, different questions (mechanisms, ecosystem services) Matter Cycles through Ecosystems o Contrast to unidirectional flow of heat (energy) o Matter is accumulated and stored as energy Cycles between organic forms and inorganic forms Decompositioncloses the cycle Nutrient BudgetsHow does a specific element travel through an ecosystem? o Pools where element is stored o Fluxes between these pools =Biogeochemistry (the first 2) o Overall gain and loss of nutrients for system Ecosystems are open cycles Only at global scale are these systems truly closed Global carbon Cycle o PICTURETownsend Fg 11-16, pg 381 o Terrestrial Community Plants uptake CO2 from atmosphere and take it in their bodies Herbivores consume, and up on the food chain All animals/plants are respiring releasing a little CO2 When animals die decomposition occurs releasing organic CO2 into the soil Microbes take up organic Carbon from soil and release it in the atmosphere Addition of burning/combustion of fossil fuels releasing carbon into atmosphere o Atmosphere composition of Carbon Atmosphere and terrestrial systems are tightly linked El Ninohigher PPM La Ninalower PPM o Human activities have altered the terrestrial Carbon cycle Emissions and pollution not the only factor contributing to increase of carbon dioxide Natural fluxes are larger than this Vulnerable Carbon Pools Foreststrap a lot of carbon in the trees Deforestation is attributed to losing 1.15 Pg C/year Frozen Soilsany organic material is not being decomposed because of extremely low temperatures, thawing increases decomposition rates Increase in carbon uptake in plant growth? More trees and shrubs Albedo Effectreflection of light Lake and wetland expansion Net emission .5-1 Pg C/year Feedbacks are unknown?? o Aquatic carbon Cycle Ocean Acidificationthe other CO2 Problem 25% of anthropogenic CO2 emissions enter the ocean CO2 and water form Carbonic Acid which reacts with carbonate ionslimiting calcium carbonate Decreased ability to grow and maintain calcium skeletons and other shell forming organisms Global Nitrogen Cycle o Terrestrial Cycling of Nitrogen Most abundant gas in the atmosphere, but relatively inert (no photosynthetic process) Nitrogen fixing bacteria obtain atmospheric nitrogen and convert them to organic nitrogen in the soil Wet fall (Nitrogen dissolved in water) Dry fall (particulates fall...
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This note was uploaded on 12/25/2009 for the course ENV S 100 taught by Professor Staff during the Fall '08 term at UCSB.

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ES100_Final Study Guide - Lecture 20 Nutrient Cycling in...

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