To accompany ‘Trees may be even bigger climate heroes than we thought’  

SCIENCE

Before Reading:

1. Explain, to the best of your understanding, how gases in the atmosphere relate to climate change. List two specific gases that you associate most directly with climate change. Now, for one of them, explain how increasing levels of this gas would likely impact our climate.
2. Describe one way that Earth’s climate is moderated naturally. Contrast this aspect of Earth to another planet — such as Mars. Feel free to do a quick internet search if necessary. Use this contrast to explain how Earth’s climate would differ without this feature.

During Reading:

1. List two human activities that release methane into the atmosphere.
2. How did methane emissions from trees in wetter soils compare to releases from trees in drier soils?
3. What do scientists mean when they talk about “gas exchange”?
4. How did researchers expect — or hypothesize — that methane emissions would change as they took measurements further up a tree trunk?
5. List three countries in which the team tested methane emissions from trees.
6. Describe the role of the plastic sheet in their experimental setup. If researchers had not used the sheet, what problem would they have encountered?
7. How many metric tons of methane does the team calculate that forests worldwide might be absorbing?
8. Contrast the metabolic rate of microbes in warmer regions to those in colder regions.
9. Kazuhiko Terazawa says this new research is important but cautions against drawing early conclusions. Explain why he thinks more research is needed to understand this issue better.
10. Besides the soil, where else might bacteria reside that could factor into a tree’s overall gas exchange?

After Reading:

1. Consider the original hypothesis made by researchers who conducted this study. To what extent did their study results support their initial hypothesis? To what extent did the results fail to support that hypothesis?
2. Imagine someone saying that because the researchers failed to support their hypothesis, the study failed. What does this person misunderstand about the scientific process? Briefly explain what you might say to this person to clear up this misunderstanding.
3. Identify one variable in this study besides trunk height and soil wetness that affected methane emission rates. How did researchers explain this difference? Come up with another variable that might also affect gas exchange but was not tested in this study. Feel free to be creative! Speculate how this variable might affect gas exchange. Briefly explain your answer.