Living in a Carbon World

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General Sherman Sequoia, Sequoia National Park.Courtesy: Wikicommons/Jim Bahn

Provenance: WikiCommons Creative Commons Attribution 2.0 Generic/Jim Bahn
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Part A: Trees - The Carbon Storage Experts

Have you ever stood next to a tree and wondered how this tree got to be so big? In California, some Giant Sequoia trees are more than 2000 years old and grow to be over 300 feet tall. General Sherman pictured in the image on the right, is the largest tree in the world by volume and is estimated to weigh over a million kilograms of mass (2,204,622 pounds). Where does all that mass come from?

Think about the question above as you watch scientists taking measurements of The President, the second largest giant sequoia in this National Geographic Video 'Magnificent Giant Tree: Sequoia in a Snowstorm.'

If the video does not load, you can view the video at this link Magnificent Giant Tree: Sequoia in a Snowstorm - YouTube

Next, watch Derek Muller of Veritasium ask people where they think a tree's mass comes from. As you watch, make note of the hypotheses suggested by people being interviewed and be prepared to compare your notes with the class.

If the video does not load, you can view the video at this link Where Do Trees Get Their Mass From? - YouTube.

Trees use the carbon from carbon dioxide to make sugar molecules

Trees, like all organisms, grow by adding mass (biomass) is the mass of living or once living material. . Carbon is the central ingredient in making that new biomass. Tree biomass is comprised of all parts of the tree; leaves, stems, branches, roots, tree trunks. The biomass of the woody tissue in the tree pictured on the right is made mostly of cellulose a long, fibrous carbohydrate (C6H12O6)n made by plants; wood and bark are made primarily out of cellulose. , a carbon compound. In a process called carbon fixation process by which photosynthetic organisms such as plants and algae turn inorganic carbon compounds (usually carbon dioxide) into organic carbon compounds (usually carbohydrate sugars). , plants transform CO₂, an inorganic carbon compound a carbon compound that does not contain both carbon and hydrogen and tends to be simpler than organic compounds. Examples would include carbon dioxide (CO₂) and carbonates (CaCO₃). into organic carbon compounds contain carbon atoms bonded to hydrogen atoms and possibly other elements such as nitrogen or phosphorous; examples include proteins, carbohydrates, nucleic acids and fats, oils and waxes. .

Plants use organic carbon compounds for energy, growth and metabolism. Examine the images of glucose and cellulose pictured below. Then, answer the checking in questions below. NOTE: Carbon atoms are grey, hydrogen atoms are white and oxygen atoms are red. Click on the images for a larger view.

Carbon atoms cycle throughout the Geosphere and Biosphere as part of millions of different types of carbon compounds

Carbon atoms are continually on the move, cycling into and out of different components of the Biosphere and Geosphere. Carbon atoms do not cycle as single atoms but instead move as part of carbon compounds. Changing from one type of carbon compound to another as carbon cycles and is stored is a key feature of the carbon cycle. You will learn more about carbon compound transformations in Lab 1C.

The amount of CO₂ trees absorb from air influences climate

Like all plants, trees are an important component of the Earth System biosphere encompasses all the living things that exist in the atmosphere, hydrosphere and lithosphere. primarily because they absorb so much carbon dioxide from the atmosphere and store the carbon in their biomass. As a greenhouse gas(GHG) atmospheric gases that warm the temperature of Earth's lower atmosphere by absorbing and emitting infrared radiation that would otherwise escape to outer space; includes carbon dioxide, methane, water vapor, ozone nitrous oxide and CFCs., carbon dioxide (CO₂) plays an important role in regulating Earth's climate. By reducing the amount of atmospheric CO_2, trees have the capacity to influence climate. You will learn more about carbon dioxide's role in regulating Earth's climate in Lab 3.

The amount of carbon stored in biomass depends on the balance of carbon input via photosynthesis and carbon output via respiration

There are three important carbon cycle processes that cycle carbon compounds into and out of trees, and into storage in biomass:

• Photosynthesis process whereby plants and algae use sunlight energy to make carbohydrate organic carbon compounds (such as glucose sugar ) from inorganic carbon dioxide (CO₂₎ and water (H₂O); plants immediately use some of their newly formed carbohydrate sugars for energy, growth, and maintenance. is the carbon cycle process that moves carbon atoms from the air into trees and all other plants. Carbon atoms move into the biosphere and into most food webs via this process.
• Respiration cellular process whereby organisms convert carbohydrates (glucose sugar), water and oxygen into energy, carbon dioxide and water; also referred to as cell respiration or cellular respiration. is the key carbon cycle process that moves carbon atoms out of plants into the atmosphere, surrounding soil or water.
• Biosynthesis refers to the production of new organic carbon compounds by a living organism; simple carbon compounds can be modified, converted into other new carbon compounds or used to build large, complex macromolecules such as proteins and DNA. is the key carbon cycle process that generates gains in biomass. Net primary production (NPP) the difference between the amount of carbon taken in via photosynthesis and the amount of carbon released via cell respiration. is a measure of the amount of carbon stored mostly as biomass.

If the carbon input from photosynthesis is greater that the carbon output from respiration, trees will biosynthesize more biomass resulting in greater carbon storage. Measures of NPP will be higher. Conversely, if the carbon output of respiration is greater than the carbon input of photosynthesis, less carbon will be stored and measures of NPP will be lower.

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Carbon Cycle of a Single Tree. Credit: Valerie Martin, TERC

1. Examine the diagram of the carbon cycle of a single tree, pictured on the right.
2. Take a few minutes to trace where the carbon goes. When you are finished, answer the Checking In questions below.

Optional Extension

Want to learn more about trees, carbon and primary production? Check out these resources:

• Read Save the Big Trees.
• Read Terrestrial Primary Production: Fuel for Life
• Use these NASA images to investigate seasonal changes in https://earthobservatory.nasa.gov/images/51289/a-global-garden-plants-storing-carbon 'NPP' new