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1、,Ecosystems,Suggested: Ch. 54: 1131-1143 Assigned: Ch. 53: 1109-1123 Ch. 54: 1145- 1151 Ch. 55 1154 1157, Fig. 55.5,Exam Information:,Dec. 17, 2001 9:00 am,Check Web & glass case outside Staging Rm. 130 for your room assignment,50 multiple choice2 hoursOnly covers Ecology Evolution,Review Sessions,D
2、ec. 12 & 13 Nat. Sci. 14512- 11- 2,community & physical environmentkey processes energy flowchemical cycling,autotrophs,primary producers,energy and nutrients,decomposers,heterotrophs,1 consumer,herbivore,o,autotrophs,primary producers,energy and nutrients,decomposers,heterotrophs,2 consumer,carnivo
3、re,o,autotrophs,primary producers,energy and nutrients,decomposers,heterotrophs,3 consumer,top carnivore,o,- photosynthesis: solar E chemical E - 1-2% of light reaching plants - GPP: gross primary productivity - 15-40% used by plant,- photosynthesis- respiration - rate new plant growth - this availa
4、ble to consumers - measured in E (J/m2/day) or Biomass (g/m2/yr),NPP: net primary productivity,- average only 10% - E lost as heat (40-60%)cellulose, bone unusable - explains why only 3-5 trophic levels,Ecological Efficiency: % energy transferred between trophic levels,- what are major global source
5、s? - open ocean (low NPP, large area) - tropical forests (high NPP, small area),- Why variation in NPP? - light, heat, nutrients,*,- 5 lakes - 18% worlds fresh water - 40 million people in GLB,pop. in great lakes black big view,- development - nutrients added: N, P - toxins: DDT, PCBs, heavy metals
6、- species introductions,Changes,- enter system via: atmospheric depositionsurface runoffgroundwater,graph of hot spotsie. red dots,Red- hazard Green- discharge,- only 1% outflow/year so accumulate - retention time depends on lake vm. - Superior 191 years, Erie-2.6 years,- all initially oligotrophic
7、- cold, clear, low nutrients - Lake Erie: added nutrients P, N - algal growth dies reduces O2 in H2O,Eutrophication,MesotrophicEutrophicOligotrophic,outline of lake edges graph,- species changese.g. trout, mayflies carp, tube worms - 1972: 80% phosphate load reduction,Biomagnification -DDT, PCBs, me
8、tals as go up food chain,Water 0.000002ppm,Level PCB (ppm) H2O 0.000001 algae 0.0025 zooplankton 0.123 smelt 1.04 lake trout 4.93 gull egg 124.0,- toxins accumulate in fatty tissues - signs disease - indicator species - risk drinking H2O vseating fish (see guidelines!),Species Introductions - lampre
9、y 1950s - alewife, smelt 50s-60s - salmonids- 60s-70s - spiney Daphnia 1980s - zebra mussel 1988 -major changes in food webs,ECOSYSTEMS - CHEMICAL CYCLES,H2O, C, N, O, P95% organisms,- evaporation, condensation, precipitation - 90% over oceans,- draining fresh water - deforestation - adding contamin
10、ants,- pH scale 1 unit = 10X - normal rain pH 5.6 - SO2 industry, NOx cars + H2O sulphuric & nitric acids - rain 2-40X more acidic,regions receiving acid rain,O 4.2,4.5,distribution of sulfur dioxide (yellow) nitrous oxides (red),- main impact downwind - Eastern NA, Scandinavia, USSR - Europe, China
11、,- effect depends on soil - basic soils buffer acid- London - granitic soils worst -Northern Ont., Muskoka, Que., Adirondacks,- pH 6 disrupts food chains - pH NH3+, NO3-N2 gas,- fertilizers runoff - burning NOx,- air 20% O2 - from photosynthesis - O3 in smog eyes, plant damage - O3 UV shield and CFC
12、s,- CL2 + O3 O2,- antarctic/arctic holes, 10-30% lower mid lats. skin cancer, disrupts food chains - Montreal 1989: 86 countries CFC production fell by 93% - return to 1950s levels by 2050,- ATP, DNA, membranes - slow weathering cycle - no gas phase - P limiting in soil & H2O,- enrichment of lakes e
13、.g. Erie - stop source input,Human Impact,- defined by vegetation - depends on temperature &rainfall over year,Biomes & Biodiversity,- 3% land, 50% species - half cut gone in 30 years - logging, cattle ranching - grow on poor soils - no regeneration if cut - cattle/crops 3-5 yrs move on.,Tropical Forests (hot, wet),- 20% gone, why save? - biodiversity loss critical,Amazon,- species mostly unknown - extinction rate 10,000 / yr. & increasing - 10% species checked - 25% drugs, 20 major food plants - 70% new cancer drugs,
