Schueller NRE 509 1 What Is an Ecosystem?

Schueller NRE 509

Schueller NRE 509 Lecture 20 & 21: Ecosystem Ecology: Matter & Energy Ecosystems: Energy flow and the production and decomposition of biomass How will the loss of animal migrations affect nutrient levels in the places they visit? 1. Intro to Systems approach & Biogeochemical Cycles Will climate change increase plant productivity, or the rate of new biomass? 2. Primary & Secondary Productivity How do we manage algal blooms causes by nutrient run-off into the Great Lakes? 3. Ecological efficiencies How do earthworms change forest nutrient cycling? 4. What determines NEP? How can we improve the energy efficiency of food 5. Decomposition systems?

Ecosystems, Energy flow, and Productivity Ecosystem Ecology What is an ecosystem? 1. Intro to Systems approach & Biogeochemical Cycles • Living plus non-living a. What is an ecosystem? components b. Pools •System c. Fluxes through which d. Turnover rates and residence times energy flows and matter cycles (Biogeochemical Cycles)

Ecosystem approach Earth is a(n) ______system with respect to energy and a(n) Boxes Pools (Reservoirs) ______system with respect to & elements. Arrows Fluxes - Processes (transformation from 1 pool to the next) A. open, closed B. open, open Ecosystem pools & fluxes => C. closed, closed Ecosystem function => D. closed, open Ecosystem services

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What are the Pools? Terminology of living parts Living (Biotic): Non-living (Abiotic):

Fig. 25.1

What are the Pools? Living plant material is NOT at the Plants, algae (phytoplankton) bottom of all photosynthetic autotrophs food chains bacteria.

In terrestrial systems, detritivores may do 80–90% of the consumption of plant matter! Carnivores heterotrophs (parasites, predators), Detritus Omnivores, Bacteria, Herbivores, Detritivores Fungi, Detritivores Detritivores Fig. 25.2

What are the Pools? What exactly is moving between pools? Biotic Abiotic: • Autotrophs • Atmosphere Macronutrients (Required in Larger Amounts): Carbon, Hydrogen, Oxygen, Nitrogen, Phosphorus, • Producers • Water Calcium, Magnesium, Potassium, Sulfur, Sodium, • Heterotrophs • Rock Chlorine • Consumers • Soil • Decomposers Micronutrients (Required in Smaller Amounts): Iron, • Detritus Manganese, Boron, Cobalt, Copper, Molybdenum, Zinc, Iodine, Selenium

= “organic matter (OM)” or “biomass” But travel in various forms: E.g. Carbon in

carbon dioxide (CO2), glucose (C6H12O), limestone (CaCO3)…

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Ecosystem approach

Boxes Pools (Reservoirs) & Arrows Fluxes - Processes (transformation from 1 pool to Inorganic Organic the next)

glucose carbon (C6H12O) dioxide (CO2), limestone

(CaCO3)

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

Fluxes: How fast? – What is the rate of moving from Fluxes: How fast? – What is the rate of moving from one ecosystem or pool to another? one ecosystem or pool to another? Residence time - How long does matter stay in one pool? • Residence time - How long does matter stay in one pool? E.g. Carbon in limestone: millions of years vs. – E.g. 4 years carbon in glucose of plant: 1 month to 400 years

E.g. Nitrogen in ocean phytoplankton vs. boreal • Turnover rate - At what rate does it forest tree trunk leave a pool (enter a new pool)? – E.g. 0.25/year

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Ecosystem Ecology Schueller NRE 509 Lecture 20 & 21: What is an ecosystem? Ecosystems: Energy flow and the production and decomposition of biomass • Living plus 1. Intro to Systems approach non-living & Biogeochemical Cycles components

•System 2. Primary & Secondary through which Productivity energy flows and matter 3. Ecological efficiencies cycles (Biogeochemical Cycles) 4. What determines NEP? Energy FLOWS through ecosystems in the form of Carbon-Carbon bonds 5. Decomposition

Fill the boxes with some of the following: And we can measure Net Primary Productivity (NPP) = net amount of Carbon fixed by producers in an ecosystem photosynthesis, respiration, NPP, GPP, producer, consumer in a time period

g C/m2/year OR Mg C/ha/year (Mg = Megagram = 106 grams)

OM less OM = New tissue, offspring g/m2/year = Rate of production

Heat & CO2 Biomass = amount of OM = “standing crop”

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

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What limits net primary productivity of an area? Patterns of Terrestrial Net Primary Productivity

Rank the productivity of:

Tropical

) Forests -1 y •Tundra -2

•Tropical rain forest Forest •Kansas corn field

•Deep ocean Arctic & Alpine Grasslands Tunda Net Primary Productivity (g m (g Productivity Primary Net

Mean Annual Temperature oC See also Stiling Fig. 26. 4

Patterns of Terrestrial Net Primary Productivity Which ecosystems are Which ecosystems, given the most productive per their area on earth, area? contribute the most to )

-1 Tropical world NPP? y

-2 -2 Forests

Temperate Forest

Grasslands

Desert Net Primary Productivity m (g Mean Annual Precipitation (mm)

See also Stiling Fig. 26. 3 http://www.globalchange.umich.edu/globalchange1/current/lectures/kling/energyflow/energyflow.html

What limits net primary productivity of an area? Liebig’s Law of the Minimum

Change in a limiting A species will be factor can speed limited by the up the rate of scarcest resource production until… (limiting factor) Ecosystem productivity is limited by the scarcest factor

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Ecosystems, Energy flow, and Productivity What limits primary productivity of aquatic systems? Hint: Soil contains about 0.5% nitrogen 2. Primary and Secondary Productivity but seawater contains only 0.00005% a. Gross Primary Productivity (GPP) nitrogen b. Net Primary Productivity (NPP), Biomass and Organic Matter (OM) c. What limits NPP? d. Net Secondary Productivity e. What limits secondary productivity?

See also Stiling Figure 26.8 Effects of nutrient enrichment on marine productivity.

Net Secondary Schueller NRE 509 Lecture 20 & 21: Productivity Ecosystems: Energy flow and the production and decomposition of biomass What limits net NSP of an area? 1. Intro to Systems approach & Biogeochemical Cycles How long can a food chain be? 2. Primary & Secondary Productivity

Depends how 3. Ecological efficiencies efficiently E is being transferred 4. What determines NEP? up the chain! 5. Decomposition

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

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Consumption (absorption) efficiency

Consumption efficiencies vary dramatically Assimilation efficiencies depends on the between different ecosystems quality of food and physiology of consumer

Rank herbivores in the following Which has the higher assimilation systems from lowest to highest efficiency? consumption efficiency: • Carnivore or herbivore? • Aquatic ecosystems • Endotherm or ectotherm? • Grasslands • Terrestrial forests

Assimilation & Production Efficiency Which has the Endotherms digest more of what they eat, but higher spend more on production maintenance, so produce less new tissue from what efficiency? they eat Ectothermic invertebrate (caterpillar) vs. endothermic mammal (squirrel) – both herbivores

Figure 25.8

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Production efficiency Another way of looking at it

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

Pyramid of Numbers

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.

Figure 25.9

Pyramid of Numbers Pyramid of Biomass Why is this one not shaped like a pyramid? (standing crop, kcal/m2 or g/m2 )

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Pyramid of Energy – How much do ecological pyramids narrow? is never inverted! (kcal/m2/yr) Figure 25.9

1 10 100 1000

“~10% rule” for E (biomass, numbers)

Consequences of Ecological Pyramids: A valid argument for eating like DDT and the food chain 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.”

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

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Ecosystems, Energy flow, and Productivity Schueller NRE 509 Lecture 20 & 21: 2. Primary and Secondary Productivity Ecosystems: Energy flow and the production and decomposition of biomass a. Gross Primary Productivity (GPP) b. Net Primary Productivity (NPP), Biomass 1. Intro to Systems approach and Organic Matter (OM) & Biogeochemical Cycles c. What limits NPP? 2. Primary & Secondary d. Net Secondary Productivity Productivity e. What limits secondary productivity? 3. Ecological efficiencies 3. Species Trophic Level Efficiencies 4. What determines NEP? = Ecological pyramids & Biomagnification 5. Decomposition

Net Ecosystem Productivity (NEP) Brainstorm: = 3 general pools of OM What causes NEP (i.e. what determines how much there is)? 1. NPP How does each item you list directly or indirectly determine Net Primary Productivity? 2. NSP

3. Detritus

Causes and Consequences of Productivity: Fill in boxes, add others, and add arrows

Abiotic factors What limits NPP &/or NSP?

Location NPP Temperature & Precipitation

Nutrients NSP

Parent material

Efficiencies depend on Biotic factors

species… So species Species composition affects composition productivity! NEP

http://www.sciencedaily.com/releases/2014/03/140311100608.htm NRE 509 Schueller

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Energy flow summary Schueller NRE 509 Lecture 20 & 21: Ecosystems: Energy flow and the Energy flows production and decomposition of biomass 1. Intro to Systems approach & Biogeochemical Cycles heat Carbon ‘cycles’: 2. Primary & Secondary Inorganic Productivity Organic OM 3. Ecological efficiencies produced & decomposed 4. What determines NEP?

5. Decomposition

• All NPP and NSP

eventually becomes Soil Insects detritus, which is subject Decomposition to the activities of decomposers = the physical and chemical breakdown of Bacteria dead plant and animal biomass = • Decomposers are only 1% “biodegrade” of total ecosystem biomass! Huge impact on: BUT they are ecologically • Nutrient availability essential! • Flux of carbon from OM to atmosphere (= “carbon emissions”) Fungi See also Figure 26.16 Energy-flow through Archaea a temperate deciduous forest.

Take EAS 430 Soil Ecology Stages of Decomposition next fall with Don Zak!

1. Leaching 2. Fragmentation 3. Chemical alteration

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Decomposition 1: Leaching Decomposition2 : Fragmentation Transfer of water-soluble materials away from organic matter (demonstrated here with blue dye) Breakdown of detritus into small pieces – High in high precipitation (by shredders) = larger surface area for microbial colonization

Detritivores

Decomposition 3: Chemical alteration Decomposition 3: Chemical alteration - Who? Fungi & Bacteria - Who? Fungi & Bacteria

- Detritus -> Humus -> Soil OM ->-> - Detritus -> Humus -> Soil OM ->->

CO2 into atmosphere + Inorganic nutrients (N, P, K, etc.) * CO2 into atmosphere +

Inorganic nutrients (N, P, K, etc.) * When do they release nutrients? • Immobilization – microbial assimilation of inorganic Clarification of common misconception: Humus does not nutrients provide C to plants! It increases CEC and moisture and • Mineralization – microbial release of inorganic slowly releases inorganic nutrients

In this picture 1. Where are the nutrients immobilized? What determines the RATE of decomposition? 2. Where is carbon “sequestered”(held in organic form, not in atmosphere)? 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!

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What determines the rate of decomposition?

Physical conditions (Climate, acidity, oxygen)

Figure 26.19 The rate of litter decomposition is affected by Litter the type quality Decomposers organisms involved.

See also Stiling Figure Physical conditions 26.20 Relationship Biochemically Identical between decomposition rates Physical conditions Leaves Decomposed in and temperature. Different Locations • Measure decay rates: – tropics months vs. Arctic decades

• Measure leaf litter thickness (=Indicator of decomposition rates) - tropics vs. temperate forest

Anaerobic (no oxygen) decomposition (Anaerobic digestion) = fermentation Physical conditions Methane-producing bacteria Decomposition is slower in • Dry, Cool climate and conditions • Acidic conditions • Water-logged soils • Anaerobic conditions

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Residence times for easily leached substances like sugars are hours to days whereas residence times for lignin are Litter (detritus) Quality months to decades.

Proteins and simple carbohydrates - fast • Gauno and animal carcasses: High nutrients! Cell walls material - slower • Most detritus = Plant Tissue that varies in nutrient quality & content Lignins (in wood) - slowest Figure 26.18 Leaf-litter • “home field advantage” decomposition – how much remains depends on content and climate.

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Nutrient rich plant material decomposes faster than Detritus in nutrient poor material. various stages of decomposition

Figure 26.23 Time course of decomposition of a pine branch, pine needle and pin- cherry leaf in a Canadian forest. (After MacLean and Wein, 1978.) Photo: Bill Currie 11/9/2017 85

Compostable vs. What is the effect of decomposition Biodegradable? seen here in this tundra? 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., soil- conditioning 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? 11/9/2017 88

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Causes and Consequences of Productivity

Add these as Consequences of NEP in your concept map: - Food chain length - Trophic cascades What are the causes and - Carbon release consequences of - Biomagnification - Carbon storage productivity? - 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? • 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)?

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