Ecosystem fluxes and cycles Carbon P and N cycles Ecosystem efficiency Toxins and bioaccumulation Water management Translocations of nutrients by organisms 1 Stocks pools compartments and flows fluxes Input Output Change in Storage 0 at equilibrium Turnover time if system is in equilibrium input vol time 1 output vol time 1 q Residence time T Volume q Turnover rate fraction of storage that is replaced in a given unit of time 1 T Ecosystem ecology Energy flows and nutrients cycle through ecosystems Humans increasingly are changing biogeochemic al cycles and spatial distributions of storage 2 Energy flows a small fraction of solar radiation is fixed by photosynthetic organisms but once energy is dissipated as heat it is never recovered by ecosystem except as passive energy savings for transport e g ocean or air currents driven by heat and used by organisms Materials cycle atoms O C N Ca P created in stars used again and again end up in different pools fluxes transfer atoms between pools We Are Stardust input storage Yellow system has shorter turnover time than blue system output input storage output 3 5 ScienceDaily June 25 1999 When Joni Mitchell in her song Woodstock sang We are stardust she was being factual as well as poetic Every element on earth except for the lightest was created in the heart of some massive star 4 6 Terrestrial bottom heavy pyramid of trophic level biomass Photosynthesis Inputs Outputs Change in storage 7 AN Ingested feces excreted assimilated EN Assimilated used for maintenance respired used for production new tissue or offspring PN IN Not consumed P N 1 Dead organic matter Begon et al 1997 9 Food produced Clean water and fish Two ecosystem services brought to you by Allocations that compete with growth and reproduction defense stress Herbivore Carnivore Microbivore Detritivore Invert Resource Production N 1 Not consumed ingested consumer Efficiency of trophic transfer for secondary production Vert ectotherm RN P n P n 1 Vert endotherm Trophic level N efficiency often 10 PN 8 I ingestion A assimilation F egestion R respiration P production 10 Food quality is an important factor affecting production efficiency Eutrophied lake Queensland Australia Inverted pyramids of trophic level biomass suppress sustain 11 12 Hydrologic water cycle Hydrologic cycle Evaporation Precipitation Transfer processes atmospheric transport runoff Most serious consequence of greenhouse warming will be the redistribution of water in space and time reduced snowpack storage in Sierra increased intensity of storms flashy runoff 13 Permeability of the surface path that water takes from land to rivers determines time interval for storage and flashiness of floods 15 land use effects e g Philippines 14 Affected areas have lost 20 of forest cover over the last 10 years Infiltration of rain reduced so flows flashy erosive Roots decay over time triggering mud slides 4 people killed by this in Coos Bay Oregon 16 1997 Plants changes in stomate behavior and roots will affect evapotranspiration and storage of water Evapotranspiration Evaporation and transpiration loss of water through stomates of plants 17 18 Less evaporation less precipitation Organic compounds contain C and H CO NH2 C6H12O6 Nutrients N P and carbon Carbon cycle Campbell p 1211 2 Campbell p 1209 Inorganic CO2 NH4 NO3Available to biota Unavailable19 20 Unavailable until mined 21 Organic compounds contain C and H CO NH2 C6H12O6 Nutrients N P and carbon 22 Phosphorus cycle No gaseous atmospheric component 2 Campbell p 1209 Inorganic CO2 NH4 NO3Available to biota Unavailable23 24 Nitrogen cycle more complex than P cycle Phosphorus Fig 27 3 Krebs P residence time algae days weeks animals days years soils months millenia ocean sediments millions of years The Nitrogen Cycle 25 26 http www physicalgeography net fundamentals 9s html Human activities fossil fuel combustion synthetic fertilizers cultivation of legumes industrial meat production have more than doubled the natural input rate of fixed 27 bioavailable nitrogen Vitousek 1997 28 Importance of land cover in retaining N high in the landscape Hubbard Brook Experiment V Smil 1997 Scientific American Curious fate of Franz Haber German chemist awarded Nobel Prize 1919 for ammonia synthesis Haber Bosch synthesis of ammonia from nitrogen and hydrogen combined at high temps and pressures explosives for WWI but world fertilizers soon thereafter allowing human population to exceed 6 billion Gene Likens also developed weaponized chlorine gas used in WWI hoping to limit overall suffering by bringing about a quicker resolution to 29 the war stream p 1214 Campbell Tree cutting completed deforested Losses during floods control 30 Ecosystem efficiency organic production nutrient flux mass time t mass time t Crust vs Dust Desert cryptogams Forests more efficient at producing wood from nutrients if these are retained ATV tracks 31 Stream Ecosystem efficiency organic production nutrient flux mass time t mass time t Terrestrial nutrient and soil retention degraded by wind erosion in desert after loss of desert crusts 32 Retentive ecosystems with short spiral lengths are more efficient more biotic production per nutrient flux downstream They also protect downstream water bodies from eutrophication flow Stream spiraling Newbold Webster downstream transport with periodic cycling by local biology Wetlands logs in rivers biological backflows e g salmon migrations increase retention ecosystem efficiency and decrease spiral length Biological backflows backflows 33 What are we doing to rivers 34 Bioaccumulation of DDT PCBs Hg and other toxins Flow regulation diversion and extraction Water extracted fine sediments solutes and heat added 35 Campbell 36 The California water system The most massive rearrangement of Nature ever attempted Kahrl et al 1978 SF Chronicle Nov 23 2003 Double edged swordfish top of their food chains and very long lived species 37 River network fragmentation blue lines on maps haven t been connected on ground for 50 years Terminus of Cowchilla R should be a tributary of the San Joaquin but dies in an agricultural field Photos W E Rainey Disturbance removal Habitat simplification fragmentation 38 Clean water and fish suppress 39 Or bottom heavy trophic pyramid dominated by Cyanobacteria in a eutrophied lake 41 sustain 40 Or bottom heavy trophic pyramid dominated by Cyanobacteria in a eutrophied lake 42 Switch from oligotrophic to eutrophic state Land conversion Clear water state loss
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