Living in a Carbon World
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
With a partner, write down ideas of where you think the mass of the Giant Sequoia tree comes from as it grows and then create a class list of all possible ideas:
- What ideas about the source of the tree's mass are you more confident about? Why? Hint: Remember that mass is a measurement of matter, and matter is made of atoms.
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.
Compare and discuss people's hypotheses from the video with your class's ideas about where the mass of a tree comes from.
- Which items on both lists are misconceptions about how a tree grows and adds mass.
- Where does a tree actually get most of its mass from?
Trees use the carbon from carbon dioxide to make sugar molecules
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
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 CO2, 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.
Carbon Cycle of a Single Tree. Credit: Valerie Martin, TERC
- Examine the diagram of the carbon cycle of a single tree, pictured on the right.
- Take a few minutes to trace where the carbon goes. When you are finished, answer the Checking In questions below.
Stop and Think
1: Using the tree diagram above to help you, explain why trees (and all plants) represent a small but complete carbon cycle. Draw your own diagram to help you illustrate your answer.
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 this NASA animation to investigate seasonal changes in https://earthobservatory.nasa.gov/global-maps/MOD17A2_M_PSN 'NPP' new