Schueller NRE 509 Lecture 20 & 21:

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1 Schueller NRE 509 Lecture 20 & 21: Ecosystems: Energy flow and the production and decomposition of biomass 1. Intro to Systems approach & Biogeochemical Cycles 2. Primary & Secondary Productivity 3. Ecological efficiencies 4. What determines NEP? 5. Decomposition

2 Ecosystem Ecology: Matter & Energy How will the loss of animal migrations affect nutrient levels in the places they visit? Will climate change increase plant productivity, or the rate of new biomass? How do we manage algal blooms causes by nutrient run-off into the Great Lakes? How do earthworms change forest nutrient cycling? How can we improve the energy efficiency of food systems?

3 Ecosystems, Energy flow, and Productivity 1. Intro to Systems approach & Biogeochemical Cycles a. What is an ecosystem? b. Pools c. Fluxes d. Turnover rates and residence times

4 Ecosystem Ecology What is an ecosystem? Living plus non-living components System through which energy flows and matter cycles (Biogeochemical Cycles)

5 Earth is a(n) system with respect to energy and a(n) system with respect to elements. A. open, closed B. open, open C. closed, closed D. closed, open

6 Ecosystem approach Boxes & Arrows Pools (Reservoirs) Fluxes - Processes (transformation from 1 pool to the next) Ecosystem pools & fluxes => Ecosystem function => Ecosystem services

7 What are the Pools? Living (Biotic): Non-living (Abiotic):

8 Terminology of living parts Fig. 25.1

9 Living plant material is NOT at the bottom of all food chains In terrestrial systems, detritivores may do 80 90% of the consumption of plant matter! Detritus Detritivores Fig. 25.2

10 What are the Pools? autotrophs Plants, algae (phytoplankton) photosynthetic bacteria. Bacteria, Fungi, Detritivores heterotrophs Carnivores (parasites, predators), Omnivores, Herbivores, Detritivores

11 What are the Pools? Biotic Autotrophs Producers Heterotrophs Consumers Decomposers Detritus Abiotic: Atmosphere Water Rock Soil = organic matter (OM) or biomass

12 What exactly is moving between pools? Macronutrients (Required in Larger Amounts): Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, Calcium, Magnesium, Potassium, Sulfur, Sodium, Chlorine Micronutrients (Required in Smaller Amounts): Iron, Manganese, Boron, Cobalt, Copper, Molybdenum, Zinc, Iodine, Selenium But travel in various forms: E.g. Carbon in carbon dioxide (CO 2 ), glucose (C 6 H 12 O), limestone (CaCO 3 )

13 Inorganic Organic carbon dioxide (CO 2 ), limestone (CaCO 3 ) glucose (C 6 H 12 O)

14 Ecosystem approach Boxes & Arrows Pools (Reservoirs) Fluxes - Processes (transformation from 1 pool to the next)

15 What are the Fluxes? What processes move matter from one pool to another? (Biological) Photosynthesis Chemosynthesis Nitrogen fixation Consumption Excretion Respiration Mineralization (Chemical/Geological) Weathering Erosion Run-off Atmospheric deposition

16 Photosynthesis and Respiration

17 Fluxes: How fast? What is the rate of moving from one ecosystem or pool to another? Residence time - How long does matter stay in one pool? E.g. Carbon in limestone: millions of years vs. carbon in glucose of plant: 1 month to 400 years E.g. Nitrogen in ocean phytoplankton vs. boreal forest tree trunk

18 Fluxes: How fast? What is the rate of moving from one ecosystem or pool to another? Residence time - How long does matter stay in one pool? E.g. 4 years Turnover rate - At what rate does it leave a pool (enter a new pool)? E.g. 0.25/year

19 Ecosystem Ecology What is an ecosystem? Living plus non-living components System through which energy flows and matter cycles (Biogeochemical Cycles) Energy FLOWS through ecosystems in the form of Carbon-Carbon bonds

20 Schueller NRE 509 Lecture 20 & 21: Ecosystems: Energy flow and the production and decomposition of biomass 1. Intro to Systems approach & Biogeochemical Cycles 2. Primary & Secondary Productivity 3. Ecological efficiencies 4. What determines NEP? 5. Decomposition

21 Fill the boxes with some of the following: photosynthesis, respiration, NPP, GPP, producer, consumer OM less OM = New tissue, offspring Heat & CO 2

22 We can measure respiration & productivity rates Flux tower Dark/light bottles

C/m 2 /year OR Mg C/ha/year (Mg = Megagram = 10 6 grams) g/m 2

23 And we can measure Net Primary Productivity (NPP) = net amount of Carbon fixed by producers in an ecosystem in a time period g C/m 2 /year OR Mg C/ha/year (Mg = Megagram = 10 6 grams) g/m 2 /year = Rate of production Biomass = amount of OM = standing crop

24 Should a forester wanting to harvest the maximum yield from a plot be more interested in the forest's standing crop or its net primary production? TIME matters Biomass/NPP = turnover time

25 Ecosystems, Energy flow, and Productivity 2. Primary and Secondary Productivity a. Gross Primary Productivity (GPP) b. Net Primary Productivity (NPP), Biomass and Organic Matter (OM) c. What limits NPP? d. Net Secondary Productivity e. What limits secondary productivity?

26 What limits net primary productivity of an area? Rank the productivity of: Tundra Tropical rain forest Kansas corn field Deep ocean

27 Patterns of Terrestrial Net Primary Productivity Net Primary Productivity (g m -2 y -1 ) Arctic & Alpine Tunda Forest Grasslands Tropical Forests See also Stiling Fig Mean Annual Temperature o C

28 Patterns of Terrestrial Net Primary Productivity Net Primary Productivity (g m -2 y -1 ) Grasslands Mean Annual Precipitation (mm) See also Stiling Fig Desert Tropical Forests Temperate Forest

Periods of hot, dry weather give rise to low primary productivity of grasses 4 Yield (t/ha) 3 2 1 (a) 0 1964 1969 1974 1979 1984 1989 1994 1999

29 Periods of hot, dry weather give rise to low primary productivity of grasses 4 Yield (t/ha) (a) Late summer hay yields at Rothamsted 2012 Pearson Education, Inc. Periods of cool, wet weather result in periods of high primary productivity

30 Which ecosystems are the most productive per area? Which ecosystems, given their area on earth, contribute the most to world NPP?

31 What limits net primary productivity of an area? Change in a limiting factor can speed up the rate of production until

32 Liebig s Law of the Minimum A species will be limited by the scarcest resource (limiting factor) Ecosystem productivity is limited by the scarcest factor

33 What limits primary productivity of aquatic systems? Hint: Soil contains about 0.5% nitrogen but seawater contains only % nitrogen See also Stiling Figure 26.8 Effects of nutrient enrichment on marine productivity.

34 Ecosystems, Energy flow, and Productivity 2. Primary and Secondary Productivity a. Gross Primary Productivity (GPP) b. Net Primary Productivity (NPP), Biomass and Organic Matter (OM) c. What limits NPP? d. Net Secondary Productivity e. What limits secondary productivity?

35 Net Secondary Productivity What limits net NSP of an area? How long can a food chain be? Depends how efficiently E is being transferred up the chain!

36 Schueller NRE 509 Lecture 20 & 21: Ecosystems: Energy flow and the production and decomposition of biomass 1. Intro to Systems approach & Biogeochemical Cycles 2. Primary & Secondary Productivity 3. Ecological efficiencies 4. What determines NEP? 5. Decomposition

37 Where do these go (on which arrows)? Consumption, Assimilation, Production

38 Transfer Efficiencies

39 Consumption (absorption) efficiency

41 Consumption efficiencies vary dramatically between different ecosystems Rank herbivores in the following systems from lowest to highest consumption efficiency: Aquatic ecosystems Grasslands Terrestrial forests

42 Assimilation efficiencies depends on the quality of food and physiology of consumer Which has the higher assimilation efficiency? Carnivore or herbivore? Endotherm or ectotherm?

43 Assimilation & Production Efficiency Endotherms digest more of what they eat, but spend more on maintenance, so produce less new tissue from what they eat

44 Which has the higher production efficiency? Ectothermic invertebrate (caterpillar) vs. endothermic mammal (squirrel) both herbivores Figure 25.8

45 Production efficiency Another way of looking at it Assimilation efficiency Ecological efficiency Consumption efficiency

46 The average trophic level efficiency is 10% Why is it so low? What are the consequences?

47 Observations In a grassland, there may be: Millions of individual plants per acre Hundreds of thousands of insects that feed on the plants Tens of thousands of insect predators A few hundred birds or mice feeding on the predatory insects.

48 Pyramid of Numbers Figure 25.9

49 Pyramid of Numbers Why is this one not shaped like a pyramid?

50 Pyramid of Biomass (standing crop, kcal/m 2 or g/m 2 )

51 Pyramid of Energy is never inverted! (kcal/m 2 /yr) Figure 25.9

52 How much do ecological pyramids narrow? ~10% rule for E (biomass, numbers)

53 A valid argument for eating like a vegetarian? According to the journal Soil and Water, one acre of land could produce 50,000 pounds of tomatoes, 40,000 pounds of potatoes, 30,000 pounds of carrots or just 250 pounds of beef. Meat is an incredibly wasteful way of producing food. That vegetable protein could be fed directly to people instead. It takes up to 16 pounds of soybeans and grains to produce 1 lb. of beef, and 3 to 6 lbs. to produce 1 lb of turkey & egg. By eating grain foods directly, I make the food supply more efficient & that contributes to the environment. Every time you eat meat, you are taking food out of the mouths of 9 other people, who could be fed with the plant material that was fed to the animal you are eating.

Hidden soy on supermarket shelves masks assault on nature Jan 14, 2014 by Carrie Svingen We consume more soy than we realize, but it is the soy that goes into pork, chicken and processed foods not

54 Hidden soy on supermarket shelves masks assault on nature Jan 14, 2014 by Carrie Svingen We consume more soy than we realize, but it is the soy that goes into pork, chicken and processed foods not the soy in tofu and sauce that is the real issue," said WWF's global soy lead Sandra Mulder. "More than half a kg of soy can be going into a kg of chicken." A lone tree stands as a reminder of the Atlantic Forest that once covered 100 million hectares in Brazil, Argentina and Paraguay. Around it, soy monocultures stretch into the distance.

55 Westhoek et al Food choices, health and environment: Effects of cutting Europe s meat and dairy intake. Global Env Change 26:196 Use of soymeal reduced by 75% 23% per capita less use of cropland for food production Nitrogen use efficiency (input: edible output) of the food system increase from the current 18% to 41% - 47% saturated fats intake reduced up to 40% 40% reduction in nitrogen emissions 25 40% reduction in greenhouse gas emissions

56 Consequences of Ecological Pyramids: DDT and the food chain

57 Consequences of Ecological Pyramids: DDT and the food chain = biomagnification or bioaccumulation Characteristics of such a pollutant: 1. Long-lived 2. Fat-soluable 3. Taken up by producers

59 Ecosystems, Energy flow, and Productivity 2. Primary and Secondary Productivity a. Gross Primary Productivity (GPP) b. Net Primary Productivity (NPP), Biomass and Organic Matter (OM) c. What limits NPP? d. Net Secondary Productivity e. What limits secondary productivity? 3. Species Trophic Level Efficiencies = Ecological pyramids & Biomagnification

60 Schueller NRE 509 Lecture 20 & 21: Ecosystems: Energy flow and the production and decomposition of biomass 1. Intro to Systems approach & Biogeochemical Cycles 2. Primary & Secondary Productivity 3. Ecological efficiencies 4. What determines NEP? 5. Decomposition

61 Net Ecosystem Productivity (NEP) = 3 general pools of OM 1. NPP 2. NSP 3. Detritus

62 Brainstorm: What causes NEP (i.e. what determines how much there is)? How does each item you list directly or indirectly determine Net Primary Productivity?

63 Efficiencies depend on species So species composition affects productivity!

64 Causes and Consequences of Productivity: Fill in boxes, add others, and add arrows Abiotic factors What limits NPP &/or NSP? Location Temperature & Precipitation NPP Nutrients NSP Parent material Biotic factors Species composition NEP NRE 509 Schueller

65 Schueller NRE 509 Lecture 20 & 21: Ecosystems: Energy flow and the production and decomposition of biomass 1. Intro to Systems approach & Biogeochemical Cycles 2. Primary & Secondary Productivity 3. Ecological efficiencies 4. What determines NEP? 5. Decomposition

66 Energy flow summary Energy flows Inorganic Organic heat Carbon cycles : OM produced & decomposed

All NPP and NSP eventually becomes detritus,

Soil Insects Bacteria BUT they are ecologically

67 All NPP and NSP eventually becomes detritus, which is subject to the activities of decomposers Decomposers are only 1% of total ecosystem biomass! Soil Insects Bacteria BUT they are ecologically essential! See also Figure Energy-flow through a temperate deciduous forest. Archaea Fungi

68 Decomposition = the physical and chemical breakdown of dead plant and animal biomass = biodegrade Huge impact on: Nutrient availability Flux of carbon from OM to atmosphere (= carbon emissions )

69 Stages of Decomposition 1. Leaching 2. Fragmentation 3. Chemical alteration

70 Take EAS 430 Soil Ecology next fall with Don Zak!

71 Decomposition 1: Leaching Transfer of water-soluble materials away from organic matter (demonstrated here with blue dye) High in high precipitation

72 Decomposition2 : Fragmentation Breakdown of detritus into small pieces (by shredders) = larger surface area for microbial colonization Detritivores

73 Decomposition 3: Chemical alteration - Who? Fungi & Bacteria - Detritus -> Humus -> Soil OM ->-> CO 2 into atmosphere + Inorganic nutrients (N, P, K, etc.) Clarification of common misconception: Humus does not provide C to plants! It increases CEC and moisture and slowly releases inorganic nutrients

74 Decomposition 3: Chemical alteration - Who? Fungi & Bacteria - Detritus -> Humus -> Soil OM ->-> CO 2 into atmosphere + Inorganic nutrients (N, P, K, etc.) * * When do they release nutrients? Immobilization microbial assimilation of inorganic nutrients Mineralization microbial release of inorganic

75 In this picture 1. Where are the nutrients immobilized? 2. Where is carbon sequestered (held in organic form, not in atmosphere)?

76 What determines the RATE of decomposition? How quickly do nutrients in detritus become available and is carbon released to the atmosphere? LIST possible independent variables of a leaf litter bag experiment!

77 What determines the rate of decomposition? Physical conditions (Climate, acidity, oxygen) Litter quality Decomposers

78 Figure The rate of litter decomposition is affected by the type organisms involved.

79 Physical conditions Biochemically Identical Leaves Decomposed in Different Locations See also Stiling Figure Relationship between decomposition rates and temperature.

80 Physical conditions Measure decay rates: tropics months vs. Arctic decades Measure leaf litter thickness (=Indicator of decomposition rates) - tropics vs. temperate forest

81 Physical conditions Decomposition is slower in Dry, Cool climate and conditions Acidic conditions Water-logged soils Anaerobic conditions

82 Anaerobic (no oxygen) decomposition (Anaerobic digestion) = fermentation Methane-producing bacteria

83 Litter (detritus) Quality Gauno and animal carcasses: High nutrients! Most detritus = Plant Tissue that varies in nutrient quality & content home field advantage

84 Residence times for easily leached substances like sugars are hours to days whereas residence times for lignin are months to decades. Proteins and simple carbohydrates - fast Cell walls material - slower Lignins (in wood) - slowest Figure Leaf-litter decomposition how much remains depends on content and climate. 11/9/

Nutrient rich plant material decomposes faster than nutrient poor material. 11/9/2017 Figure 26.

85 Nutrient rich plant material decomposes faster than nutrient poor material. 11/9/2017 Figure Time course of decomposition of a pine branch, pine needle and pincherry leaf in a Canadian forest. (After MacLean and Wein, 1978.) 85

86 Detritus in various stages of decomposition Photo: Bill Currie

Compostable vs. Biodegradable? U.S. Federal Trade Commission (FTC) Green Guides (Bio)degradable: will completely break down and return to nature (i.e., decompose into elements found in nature) within a reasonably short period of time [one year] after customary disposal.

87 Compostable vs. Biodegradable? U.S. Federal Trade Commission (FTC) Green Guides (Bio)degradable: will completely break down and return to nature (i.e., decompose into elements found in nature) within a reasonably short period of time [one year] after customary disposal. Compostable: all the materials in the item will break down into, or otherwise become part of, usable compost (e.g., soilconditioning material, mulch) in a safe and timely manner (i.e., in approximately the same time as the materials with which it is composted) in an appropriate composting facility, or in a home compost pile or device Which is more like decomposition?

88 What is the effect of decomposition seen here in this tundra? 11/9/

89 What are the causes and consequences of productivity?

90 Causes and Consequences of Productivity Add these as Consequences of NEP in your concept map: - Food chain length - Trophic cascades - Carbon release - Biomagnification - Carbon storage - Climate change - Biomass - Harvest amount and rate

Self assess (chew on these) Why might standing biomass (amount!) not be correlated with productivity (rate!)? What variable would be a good indicator of net primary productivity?

91 Self assess (chew on these) Why might standing biomass (amount!) not be correlated with productivity (rate!)? What variable would be a good indicator of net primary productivity? What is the ultimate source of energy? What is the ultimate fate of energy? What factors determine ecological efficiency of an organism? Of an ecosystem? Is vegetarianism more efficient? Does the way energy is lost at each trophic level put a limit on how many trophic levels a system can have? What might be the consequences for ecosystems of an increase in average global temperature? Follow the causal link through the production and decomposition of productivity What actions could you take to slow down decomposition (as a way to increase carbon sequestration)?

Class XII Chapter 14 Ecosystem Biology

Class XII Chapter 14 Ecosystem Biology Question 1: Fill in the blanks. (a) Plants are called as because they fix carbon dioxide. (b) In an ecosystem dominated by trees, the pyramid (of numbers) is type. (c) In aquatic ecosystems, the limiting