Last week Inorganic carbon in the ocean, Individual carbon emissions, Primary productivity Today Review last weeks activity Limiting factors - nutrients, Controls on Productivity

The atmosphere, by volume, consists of: 78% N 2 atomic weight % O 2 atomic weight 16 1% Ar atomic weight % (360 ppm) CO 2 atomic weight 44 Using the composition of the air and the table of atomic weights above calculate the mean molecular weight of air. Nitrogen 0.78 x 2(14)= Oxygen0.21 x 2(16)= 6.72 Argon0.01 x 40= 0.40 CO x (12 + 2(16))=

The total mass of the atmosphere is 5 x g. Using the mean molecular mass of air calculated above determine the number of moles of air. 5 x g / g/mole= 1.73 x moles

If 21% of the air is oxygen (O 2 ) (by volume or moles, as a mole of any gas always takes up the same volume at a given temperature and pressure), calculate the number of moles of O 2 in the atmosphere. 21% = a fractional amount of 0.21, so 0.21 x 1.73 x moles = 3.6 x moles of oxygen gas

Fossil fuel reserves are estimated to contain 6x10 18 g carbon. At 12 grams per mole, how many moles of carbon is this? 6 x g carbon / 12 g of Carbon/mole= 5 x moles of carbon

What fraction of the atmospheric oxygen would be consumed by burning all the world’s fossil fuels? Express this as a % reduction in O 2. Is this a significant amount? How much would CO 2 increase? CH 2 O + O > CO 2 + H 2 O Part I For each mole of carbon in CH 2 O (our fossil fuel) combustion requires one mole of O 2 First we need to know how many moles of fossil fuel carbon there are, but we already did that in question d = 5 x moles of carbon. Since the molar ratio of oxygen to carbon is 1 to 1, if we burn 10 moles of carbon we need 10 moles of oxygen; 1000 moles of carbon requires 1000 moles of oxygen. Therefore 5 x moles of carbon requires 5 x moles of oxygen

What fraction of the atmospheric oxygen would be consumed by burning all the world’s fossil fuels? Express this as a % reduction in O 2. Is this a significant amount? How much would CO 2 increase? CH 2 O + O > CO 2 + H 2 O Part II From Part I 5 x moles of carbon requires 5 x moles of oxygen Next we need to figure out the percentage of the total amount of oxygen in the atmosphere we would use. We know from above that we have 3.6 x moles of oxygen gas in the atmosphere. So we calculate the percentage 5 x moles of oxygen used / 3.6 x moles of oxygen gas in the atmosphere = 14%

Burning of biomass (i.e. trees in the tropical rain forests, etc...) would also consume atmospheric oxygen. This biomass contains 600 Gtons or 6x10 17 g of carbon. If, in addition to burning all the fossil fuels, we burned all the forests, would that make a significant difference in decreasing atmospheric oxygen? (No need for calculations for this question, base you answer on the calculations already done and the relative size of the reservoirs of carbon) This one was a little tricky, but not too hard if you looked at the other questions. If fossil fuels contain 6 x g carbon and that didn’t make a huge difference, then biomass, which at 6x10 17 g of carbon is only 10% of the total amount of fossil fuels probably won’t either.

Human activities including burning of biomass and fossil fuel have increased the amount of CO 2 in the atmosphere from 280 ppmv (parts per million by volume) or % in pre-industrial times to 365 ppmv (or %) today. How many moles of CO 2 have been added to the atmosphere? Now = % - pre-industrial % = an increase of % % (increase)x 1.73 x moles (total mass of atmosphere in moles from above) = 1.47 x moles of CO 2 added to the atmosphere

It has been estimated that humans have consumed a total 240 Gtons or 2.4x10 17 g of carbon through the burning of fossil fuels. Assume that all this carbon was converted to CO 2. How much would this increase the CO 2 in the atmosphere? 2.4x10 17 g of carbon / 12 g carbon/mole = 2.0 x10 16 moles of carbon By how much does this differ from the value calculated above? From previous question atmospheric increase equals 1.47 x moles of CO 2 - more than 10 times as much has been burned What might explain this difference?

Photosynthesis Primary Productivity - the amount of organic matter produced by photosynthesis per unit time over a unit area CO 2 + H 2 O + Sun Energy--> CH 2 O + O 2 Converts inorganic carbon to organic carbon Removes carbon from atmosphere to organic carbon in biomass and soil organic carbon - residence time about 10 years Producers or Autotrophs are the majority of biomass

Respiration CH 2 O + O 2 --> CO 2 + H 2 O + Energy Reverse of photosynthesis Converts organic carbon to inorganic carbon --> releases energy Consumers or Heterotrophs - organisms that utilize this energy - small part of biomass (1%) Aerobic respiration - with oxygen

Respiration, cont. Processes is accelerated by enzymes Half of gross primary productivity is respired by plants themselves Other half is added to organic layer in soils --> microbes - bacteria and fungi break down this organic matter Below the surface - Anaerobic respiration without oxygen

Marine vs. Terrestrial Carbon Cycling Primary Productivity takes place both in oceans and on land On lands - green plants In oceans - phytoplankton - free floating photosynthetic organisms What controls marine photosynthesis?

–Sunlight/ Energy –Nutrients –CO 2

Map of Ocean productivity - nutrients are the key

Ocean a Source or Sink Sinks vs. Sources Why this pattern? = Nutrients and CO 2

Controls on Net Primary Productivity Nutrients

Only about 44% of the total Electromagnetic energy reaching the earth is in the correct wavelengths for use by plants (called PAR) and only 0.5% – 3% of that is used!

Temperature is a strong Limiting factor. Although plants in colder areas are optimized for Colder conditions

Water also is a strong Limiting factor. Much steeper curve = A much stronger positive Reaction i.e. a little water goes a long way!

Ecosystem Type Net Primary Productivity (kilocalories/meter 2 /year) Tropical Rain Forest 9000 Estuary 9000 Swamps and Marshes 9000 Savanna 3000 Deciduous Temperate Forest 6000 Boreal Forest 3500 Temperate Grassland 2000 Polar Tundra 600 Desert 200 Net Primary Productivity of Different Systems * Kilocalories are what we call “Calories” in everyday usage

Carbon Budgets: what they are and why they matter Mike Ryan, USDA Forest Service Rocky Mountain Research Station

Carbon Budget Leaves make sugar from CO 2 and water. These sugars are used to support plant metabolism and grow new leaves, wood, and roots. Most of the carbon that stays on site is in wood. Soils contain much carbon, but it changes slowly.

Objectives Why are carbon budgets important? What is the size of the components? What controls the process? How do we measure them? Examples: Radiata pine, Eucalyptus

Why are C Budgets Important? Help put wood growth in context of other processes There are 2 ways to grow more wood: Fix more sugars or use more of what’s there for wood Managing for carbon?

WOOD GROWTH Is a small portion of photosynthesis Depends on both photosynthesis and allocation Is very sensitive to environment

Foliage NPP Foliage Respiration Wood Respiration Wood NPP Root Production + Respiration + Exudates + Mycorrhizae GPP Lets look at the entire budget: 10% 20% 40% 15%

What are the Processes? Photosynthesis AllocationRespiration

What Controls the Processes?

Photosynthesis Nutrients control the amount of leaf area and how well it will work Leaf area controls how much light is absorbed Humidity controls CO 2 uptake during the day Soil water controls CO 2 uptake seasonally

Respiration Temperature controls rate Nutrient concentration controls amount Closely related to photosynthesis and growth Over a year respiration is about 50% of photosynthesis

Allocation Nutrition can shift allocation from roots Environment: dry climate can shift allocation to roots Genetics Fertility can rapidly change allocation to wood

How do we Measure? Photosynthesis: IRGA, generally to measure response to environment and photosynthetic capacity. Models used to extrapolate.

How do we Measure? Respiration: IRGA, generally to measure response to environment and growth. Models used to extrapolate.

Like measuring the flow of water into a tub from an underwater faucet (= outputs – inputs + storage change) TBCA = F S - F A + storage change How do we Measure? Belowground Allocation Litterfall Soil Respiration Soil Litter Roots

Studies use measurements of the entire C budget to measure GPP and allocation Foliage NPP Foliage Respiration Wood Respiration Wood NPP Root Production + Respiration + Exudates + Mycorrhizae GPP

Eucalyptus in Hawaii January 1999, 55 months after planting

Eucalyptus Carbon Budget (Tons C ha -1 yr -1 ) Fertilization increased growth and respiration (by increasing leaf area and photosynthesis and by changing allocation)

Examples: Light can limit productivity, So can water, and Certain nutrients too Limiting Factors for Biological Productivity - Plants never seem to be able to “fix”, or assimilate all the carbon available to them – something is limiting production - This is true both on land and in the ocean

In 1840, J. Liebig suggested that organisms are generally limited by only one single physical factor that is in shortest supply relative to demand. Liebig's Law of the Minimum Now thought to be inadequate – too simple! - complex interactions between several physical factors are responsible for distribution patterns, but one can often order the priority of factors

Phosphorus Is very often limiting in freshwater systems What is happening here? Why doesn’t the line keep Going up?

As we’ve seen in the ocean, nutrients are often limiting. Why nutrients? Needed for enzymes, cellular structures, etc. Pretty much analogous to vitamins for humans Soon as you meet the requirements for one, another ends up being limiting

Nutrient elements needed for all life C HOPKINS Mg CaFe run by CuZn Mo Hydrogen Carbon Zinc Molybdinum Oxygen Copper Calcium Phosphorus Magnesium Iron Iodine Potassium Nitrogen Sulfur

Order of Importance of Nutrient Elements in Different Environments On LandIn FreshwaterIn the Ocean 1) Nitrogen1) Phosphorus 1) Iron 2) Phosphorus2) Nitrogen 2) Phosphorus 3) Potassium3) Silica 3) Silica

As we’ve seen, nutrients are often limiting. Why nutrients? Needed for enzymes, cellular structures, etc. Pretty much analogous to vitamins for humans Soon as you meet the requirements for one, another ends up being limiting

In addition to primary productivity being a major sink for atmospheric CO 2, it is also the base of the food chain and allows humans and all Other creatures to live, and… It takes a lot of primary production to support higher trophic levels! Data from Whittaker, R.H Experiments with radiophosphorus tracer in aquarium microcosms. Ecological Monographs 31:

1. Carbone, C. & Gittleman, J.L. A common rule for the scaling of carnivore density. Science, 295, , (2002). 2.Enquist, B.J. & Niklas, K.J. Global allocation rules for patterns of biomass partitioning in seed plants. Science, 295, , (2002). Every Kg of predator needs 111Kg Of prey living in the same area for the System to stay stable

OK, so we need to know what control productivity both for Global climate and for organisms that live here (including humans!) We saw that water and temperature are very important, and that there Is a huge response to small change in water. But what about the Nutrients we talked about on Tuesday? What affect do they have?

Phosphorus Is very often limiting in freshwater systems What is happening here? Why doesn’t the line keep Going up?

Multiple or co-limiting factors – often it is more Complex than Liebig’s Law of the minimum Look what happens with the addition of N

Multiple or co-limiting factors – often it is more Complex than Liebig’s Law of the minimum This is real live data from a real live experiment

Nutrient Inputs to Ecosystems Important nutrients for life generally enter ecosystems by way of four processes: (1). Weathering (2). Atmospheric Input (3). Biological Nitrogen Fixation (4). Immigration Red means humans have a huge impact on these processes

Nutrient Outputs from Ecosystems Important nutrients required for life leave ecosystems by way of four processes: (1). Erosion (2). Leaching (3). Gaseous Losses (4). Emigration and Harvesting Red means humans have a huge impact on these processes

In well functioning ecosystems relatively small amounts of Nutrients enter or leave. Most of what is needed comes from internal recycling! (true for all systems not just aquatic)