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Home , Biomass (ecology), Ecological efficiency, Photosynthesis, Productivity (ecology)

2.3 Flows of & Matter - Significant Ideas

• are linked together by energy and matter flow • The ’s energy drives these flows and are impacting the flows of energy and matter both locally and globally Knowledge & Understandings

• As solar radiation (insolation) enters the ’s some energy becomes unavailable for ecosystems as the energy absorbed by inorganic matter or reflected back into the atmosphere. • Pathways of radiation through the atmosphere involve the loss of radiation through reflection and absorption • Pathways of energy through an include: • Conversion of to • Transfer of chemical energy from one to another with varying efficiencies • Overall conversion of UB and visible light to heat energy by the ecosystem • Re-radiation of heat energy to the atmosphere. Knowledge & Understandings

• The conversion of energy into for a given period of time is measured by productivity • Net primary productivity (NPP) is calculated by subtracting respiratory losses (R) from gross primary productivity (GPP) NPP = GPP – R • Gross secondary productivity (GSP) is the total energy/biomass assimulated by consumers and is calculated by subtracting the of fecal loss from the mass of eaten. GSP = food eaten – fecal loss • Net secondary productivity (NSP) is calculated by subtracting the respiratory losses (R) from GSP. NSP=GSP - R Applications and Skills

• Analyze quantitative models of flows of energy and matter • Construct quantitative models of flows of energy or matter for given data • Analyze the efficiency of energy transfers through a system • Calculate the values of both gross primary productivity (GPP) and net primary productivity (NPP) from given data • Calculate the values of both gross secondary productivity (GSP) and net secondary productivity (NSP) from given data Key terms

• Gross productivity (GP) • Gross Primary Productivity (GPP) • Gross Secondary Productivity (GSP) • Net productivity • Net Primary Productivity (NPP) • Net Secondary Productivity (NSP) • Primary productivity • Secondary productivity What happens to solar radiation entering Earth’s system?

3% absorbed by clouds 100% entering 17% absorbed by solar molecules & dust radiation

49% absorbed by ground Figure 10.1 Photoautotrophs

Only 0.06% of all solar radiation falling on Earth is captured by photoautotrophs! in

• are the location of photosynthesis in plants • In all parts of plants – , stems,… • Green color from (photosynthetic ) • Found in cells of mesophyll – interior of leaves • Gases exchanges through the stomata • enters through xylem of Figure 10.2 Focusing in on the location of photosynthesis in a Energy Processes

• Photosynthesis (Green Plants) +water + dioxide  +

• Respiration (All living things) oxygen + sugars  ATP +water +

• ATP is molecular energy storage Producers

• Make their own food - photoautotrophs, chemoautotrophs • Convert inorganic materials into organic compounds • Transform energy into a form usable by living organisms Photosynthesis

• Inputs – sunlight, carbon dioxide, water

• Outputs – sugars, oxygen

• Transformations – into chemical energy, inorganic carbon into organic carbon Respiration

• Inputs - sugars, oxygen

• Outputs - ATP, carbon dioxide, water

• Transformations – chemical energy in carbon compounds into chemical energy as ATP, organic carbon compounds into inorganic carbon compounds

Ecological Efficiency Ecological Efficiency

Pearson Environmental Systems and Societies 2015 Primary Productivity

• The gain of energy or biomass by producers, per unit area per unit time. • The conversion of into chemical energy. • Depends on amount of sunlight (insolation) available, the efficiency of the producers to perform photosynthesis, and the availability of other factors needed for growth ().

Distribution of World Productivity

• Primary productivity is highest where conditions for growth is highest • High levels of insolation • Good water supply • Warm • High nutrients • Constant growing seasons Secondary Productivity

• The biomass gained by consumers and through feeding and absorption • Measured in mass or energy per unit area per unit time • Depends on the amount of food available and the efficiency of the consumers for turning it into new biomass Gross Productivity (GP)

• Total gain in energy or biomass produced per unit area per unit time • Varies across the surface of the earth • Generally greatest productivity • In shallow near continents • Along reefs – abundant light, heat, nutrients • Where currents bring nitrogen & phosphorous to the surface • Generally lowest • In & arid regions with lack of water but high temperatures • Open lacking nutrients and sun only near the surface Net Productivity (NP)

• The gain in energy or biomass minus amount used by organism through respiration (R) • Some of GP used to stay alive, grow and reproduce • NP is what’s left • Most NP • , , tropical • Least NP • Open ocean, , • Open ocean has low NP but its large area gives it more NP total than anywhere else Ocean Area vs Productivity

Productivity & Agricultural Land

• Highly modified, maintained ecosystems • Goal is increasing NPP and biomass of crop plants • Add in water (irrigation), nutrients (fertilizer) • Nitrogen and phosphorous are most often limiting to crop growth • Despite modification NPP in agricultural land is less than many other ecosystems GROSS PRIMARY PRODUCTIVITY (GPP)

• The rate at which producers use photosynthesis to make more biomass • The mass of created per unit area per unit time NET PRIMARY PRODUCTIVITY (NPP)

• The rate at which energy for consumers is stored in new biomass per unit area per unit time after subtracting respiratory losses (R) • This is the amount of energy/biomass available to the consumers at the next trophic level • NPP = GPP - R Productivity Calculations

• Total Primary Productivity = Gross (GPP)  Amount of light energy converted into chemical energy by photosynthesis per unit time • Joules / Meter2 / year • Net Primary Productivity  GPP – R, or GPP – some energy used for respiration in the primary producers (R = respiratory loss) • Represents the energy storage available for the whole of consumers • Standing crop = Total living material at a trophic level Experiments to Calculate Productivity (Light/Dark Rxns)

• Use aquatic plants • Measure both photosynthesis and respiration by looking at oxygen levels • In water we must measure dissolved oxygen (DO) – indirect measure • NPP can be estimated by measuring the increase in DO when in light • GPP can be calculated by measuring the decrease in DO when put in the dark (only respiration (R) will occur) • NPP = GPP – R so GPP = NPP + R Experiments to Calculate Productivity (Light/Dark Rxns)

• You start a light bottle/dark bottle measurement on X with 10 mg/L of oxygen in both bottles. You let the bottles sit for 1 week so that photosynthesis and respiration rates can be calculated. At the end of 1 week, you have 7 mg/L of oxygen in your dark bottle and 12 mg/L oxygen in your light bottle. What is the NPP, GPP, and respiration? Experiments to Calculate Productivity (Light/Dark Rxns)

• You start a light bottle/dark bottle measurement on algae Species X with 10 mg/L of oxygen in both bottles. You let the bottles sit for 1 hour so that photosynthesis and respiration rates can be calculated. At the end of 1 week, you have 7 mg/L of oxygen in your dark bottle and 12 mg/L oxygen in your light bottle. What is the NPP, GPP, and respiration?

• NPP = 12 mg/L – 10 mg/L = 2 mg O2 per liter per week

• Loss of dissolved O2 (R) = 10 mg/L – 7 mg/L = 3 mg/L/wk • NPP = GPP – R so GPP = NPP + R

• GPP = 2 + 3 = 5 mg O2/L/wk Problems

Dissolved Oxygen (mmol/L) in water samples from Lake Ashby Transparent Bottle Opaque Bottle Initial, 6 a.m. 0.288 0.288 Final, 9 a.m. 0.292 0.282 Difference 0.004 0.006

1. Write the equation for and calculate the GPP 2. Write the equation for and calculate the NPP 3. Write the equation for and calculate the Respiration GROSS SECONDARY PRODUCTIVITY (GSP)

• The total energy or biomass assimilated by consumers • GSP = food eaten – fecal loss NET SECONDARY PRODUCTIVITY (NSP)

• The gain by consumers in energy or biomass remaining per unit area per unit time after respiratory losses • NSP = GSP - R More Productivity Calculations

Producers: • NPP = GPP – R

Consumers: • GSP = Food eaten – fecal losses • NSP = change in mass over time • NSP = GSP – R Measuring Secondary Productivity

• Gross Secondary Production • Measure the mass of food eaten by an organism (best if controlled diet in lab) • Measure mass of waste (excrement, shedding, etc.) produced • GSP = food eaten – mass of feces • Net Secondary Production • Measure organism’s starting mass and ending mass for experiment duration • NSP = Ending Mass – starting mass Calculating GSP, NSP, and R

Experiment was carried out over 5 days. • NSP - gain in biomass of stick insect • 9.2g – 8.9g = 0.3 g / 5 days = 0.06 g/day • GSP = food eaten – fecal loss • Food eaten 29.2g – 26.3g = 2.9g • GSP = 2.9g – 0.5g = 2.4g/ 5 days = 0.48g/day • NSP = GSP – R So R = GSP – NSP • R = 0.48 g/day – 0.06 g/day = 0.42 g/day Method evaluation

• GSP method difficult in natural conditions • Even in lab hard to get exact for waste

• NSP method hard to document mass change in organism unless it is over a long time period What types of things effect productivity?

• What can we measure for an experiment? • Effects of light exposure – strength, time, color, … • Effects of • Differences between types of plants • Differences between types of producers • Effects of additions • Effects of salinity