Grading so far….

1. Grading so far…. • Midterm (n= 67 exams) • highest= 96, median = 79 • A, A-: 16 exams >= 87 • B+, B & B-: 23 exams 74-86 • C+, C & C-: 25 exams 53-73 • Essay #1

2. The Flux of Energy & Matter through Ecosystems • These fluxes tie biological communities to the abiotic environment; both together are called ecosystems • Biomass is the standing crop of living organisms and is expressed as dry matter (kg) per unit area (or energy (joules)/area in case of energy flow) • Primary productivity (PP): rate at which biomass is produced • Net primary productivity (NPP): energy produced by plants minus energy lost as as community respiratory heat • Secondary productivity: rate of biomass production by heterotrophs (non-autotrophs or non-plants)

3. Total NPP summed for each of the Earth’s biomes- tropical rain forests & savannas highest- marine & terrestrial totals similar

4. Net PP from the biomass of different ecosystems- higher productivity for aquatic & non-forest for given biomass

5. Ultimately, the functioning and nature of biological communities depends on plant productivityPlant net productivity varies with latitude- forests:boreal: 1025 gC/m2/yr temperate: 1400 gC/m2/yr tropical: >3000 gC/m2/yr a) grasslands & tundra b) cultivated crops c) lakes These relationships suggest that temperature & radiation limit NPP

6. What limits Primary Productivity?- for terrestrial communities, 4 possible resources and a condition (temperature) Radiation from the sun …. not usually a limiting factor Photosynthetic efficiency maxes out at only 1-3% of available radiation …..although under optimal conditions, crop plants may achieve 3-10% 2) Carbon dioxide Some communities respond to global increases in CO2) …..but concentration similar around earth, so can’t explain differences ….

7. 3) Rainfall & 4) Temperature are critical factors that commonly limit primary productivitya) savannas (global sample) b) all ecosystems (Tibetan plateau)

8. 5) Mineral nutrients (N & P especially, sometimes micronutrients) are often limiting factors where rainfall abundant--- fertilization works!-*limiting factors change seasonally in most ecosystems - length of growing season & temp/water NA broadleaf forests: Sandy soils are water- & N-limited

9. Aquatic systems Mineral nutrients commonly limit production in aquatic ecosystemsphytoplankton in Canadian lakes upwelling zone (nutrient-rich) -shading effect nutrient-poor marine area b&c: Namibia ocean phytoplankton

10. Net PP rises, then declines during succession- early successional pine vs. late successional fir Managing a forest for Carbon sequestration?

11. Not surprisingly, secondary productivity is positively related to primary productivitya) zooplankton in lakes b) bacteria in water c) Caterpillars on Daphne Island, Galapagos

12. Transfer efficiencies- only 10% of PP is converted in aquatic & terrestrial systems Much primary productivity is not consumed by grazers and supports the decomposer community CE= consumption efficiency 2) Not all consumed biomass is assimilated into consumer biomass AE= assimilation efficiency 3) Some assimilated biomass is converted and lost as respiratory heat PE= production efficiency

13. Trophic transfer efficiency (=CE x AE x PE) varies tremendously between trophic levels and communities (e.g., variation in 48 studies of TTE in aquaticcommunities)

14. General patterns of energy flow for different communities: - note major distinctions in % NPP flows to consumers vs. decomposers- plankton: “live consumer community”; terrestrial: low consumption

15. Dramatic differences in % NPP consumed by herbivoresvs. channeled into dead organic matter (DOM)

16. The Process of Decomposition • release of energy and the mineralization of chemical nutrients • gradual disintegration of dead bodies & other organic matter through biological and physical agents • finally, breakdown into CO2, H2O & inorganic nutrients by consumers of dead organic matter • These consumers are: • Decomposers (bacteria & fungi) • Microbivores (tiny animals feeding on detritus, bacteria & fungi • Detritivores (larger generalized feeders)

17. Organisms of the Terrestrial Decomposer Food Web:- Classification by Size- Invertebrate decomposers are very diverse

18. Plant decomposition depends on mutualisms for cellulose digestion with either gut microflora (bacteria) ormicrofauna (protozoa in termite guts) - Interactions between species are important and increase overall levels of decomposition, indicating some “facilitation” (e.g., Alder leaf loss increased as more stonefly species participated) Stoneflies are bioindicators of stream health

19. Consuming carrion & feces- Carnivores scavenge & digest animal bodies with high efficiency (80%)- Herbivore feces is less digestible but specialists recycleisopods speed breakdown & recycling of caterpillar feces

20. African dung beetles were deliberated imported into Australia in 1963 to solve problem of massive accumulations of bovine feces or “cow pies” - 300 million pies/day generated with loss of 2.5 million ha/yr under dung!- now 20 spp introduced

21. Flux of matter through ecosystems: Pools of chemical elements in atmosphere, lithosphere (rocks) & hydrosphere (water) Biogeochemistry: Study of fluxes of elements between these three compartments Components of nutrient budgets of a terrestrial & aquatic system linked by streamflow

22. Annual carbon budget for a ponderosa pine (Oregon) Units: gC/m2 & gC/m2/yr Respiratory heat loss From herbivores tree roots litter soil carbon

23. - small & large phytoplankton most important Pathways of carbon in the ocean All water bodies receive inputs from land, so human activities critical - vast amounts of methane ice trapped in continental shelf sediments (19x damaging re CO2 greenhouse gas)

24. Global Biogeochemical Cycles: nutrients move around globe by winds and water-the hydrological cycle showing fluxes & reservoirs of water

25. Read about the major reservoirs & fluxes for these four key nutrient elements

26. Lowlights of Pollution • Pollution: contamination of environment by human waste and by unwanted products of human activities • Homo sapiens unique in: • using fire, fossil fuels and nuclear fission to do work & transform landscapes • mine, smelt & transform metals • create new chemicals • alter atmosphere and climate on large scale • We will focus on pollution of natural systems • Note that other courses in the Environmental Management program deal with these issues in detail

27. Effect of 1947 DDT pesticide introduction on wild bird eggshell thicknesssome peregrine falcon populations dropped to 10% of former size; others went extinct • Sparrowhawk eggshell thickness index • Correlated with DDT use

28. Environmental Economics: valuation of ecosystem services and of net loss from human activities Provisioning services Wild foods, fibers, timber, water 2) Regulating services Regulation of climate, floods, filtering of pollutants 3) Supporting services Primary production, nutrient cycling, soil formation 4) Cultural services Spiritual, esthetic fulfillment, scientific, recreational

29. Valuation of lost services: Indonesian forest fires of 1997: 50,000 km2 burned Replacement cost Lost forest and agricultural products, clean water, tourism income, health care from smoke pollution Increased greenhouse gas emissions 2) Contingent valuation Public willingness to pay for different forest use scenarios Total estimated loss of 4.5 billion $$

30. Agricultural Pollution: runoff of nitrates, insecticides and herbicides (ex.: nitrate leaching from soils and fertilizer; Germany)

31. Agricultural Pollution: managing agricultural runoff by restoring wetlands 148 wetlands under construction in Sweden to capture 40% of N before entering Baltic Sea

32. Managing eutrophication through biomanipulation Objective: reduce plankton bloom due to N & P runoff in Lake Mendota, Wisconsin • 1987: introduced two piscivorous fish spp • zooplankton increase as predatory fish reduced by piscivores • Larger zooplankton species bedame dominant, efficiently grazing on phytoplankton and improving water clarity

33. Pesticide PollutionBiomagnification of two classes of pesticides in the Barents Sea:chlordanes & PCBs- transport to the Arctic is from river runoff, and oceanic and atmospheric circulation- chlordanes are biomagnified less than PCBs

34. Fossil Fuels & the Atmosphere The Mauna Loa Observatory data tracking CO2 & the earth’s seasonal respiration (from 280 ppm to 380 today, to 700 by 2100?)

35. Net change- Earth’s surface temperature: - extremes in temp & rainfall to increase- map of 1951 to 1997 changes in temp

36. Predicted changes in the distribution of the Argentine ant by 2050 Red= improved conditions, blue = worse

37. CO2 emissions are from fossil fuels in the temperate developed world, but more from deforestation & burning in the tropical/underdeveloped world

38. Dubious US leadership in per capita carbon emissions & easy policy solutions in the transportation sector

39. Acid rain: pollution by sulfur dioxide & nitrogen oxides Diatom changes in Irish lake > 1900 If pH --> 4.0-4.5, then Al, Fe & Mn increase & toxic to organisms Spruce forest damage…. US EPA: “allowance trading” - some success

40. Pollution causing thinning of ozone layer over the Antarctic: - but now a successful example of effective international policy • Sept 24, 2006 image • -blue: thinnest layer • -avg size Sept 7 - Oct 6 each yr • The Montreal Protocol has led to reductions in production of damaging chemicals…. But the Kyoto Protocol lacks similar legal sanctions

41. Environmental costs of mining Toxic & sterile environment at world’s largest open pit mine, Utah -Copper leaches as toxic waste into rivers -Copper concentrate heated, so drives off arsenic & other toxic metals into atmosphere