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高二教案 第809期(2)

本期配套教案共2页:  1  2

Balancing forests and CO2 (P6)
河北师大附中 赵乃平
Lead in
What environmental problems are troubling us?

What are the causes?
Human behavior
Read for main idea
Balancing forests and CO2

What is the passage mainly about?
The passage is mainly about whether planting trees is an effective means to improve the environment in the long run.
Read for details
What was one way people tried to deal with climate change in the past?
They planted more trees.

How does it work?   
CO2 in the air is absorbed by trees.
The amount of CO2 in the air is greatly reduced. Thus, the air quality improves.

What is a limitation of that practice?
Trees must stay alive. Once they die, they will release the CO2 back into the air.
“carbon flux”
the movement of carbon between forest and the atmosphere

What have recent studies found?
Trees are growing faster than before.

What is probably the cause?

What is the relationship between the trees' growth rate and their length of life?
In general, a faster growth rate will lead to a shorter life.

What method did Brienen and his colleagues use?
They counted the number of tree rings and also measured the widths.

What did they find?
The faster a tree grows, the younger it may die; or the slower a tree grows, the longer it may live.

What does “the trade-off between growth and lifespan held strong” mean?
A balance is kept between a tree's growth rate and its lifespan.
A tree can't enjoy both a rapid growth rate and a long lifespan at the same time.
If it grows fast, it will die young. A slower growth rate could lead to a longer lifespan.

According to Brienen, what will happen in 20 years?
The present trees will begin dying and releasing CO2 that they have pulled from the air.

What is Brienen’s suggestion when it comes to cutting down on CO2 levels?
He suggested solving the problem from the root. We should stop releasing CO2 into the atmosphere.
Read for thinking
As teenagers, what can we do to help improve the environment?
take public transport;
save electricity, water, paper...;
reduce rubbish;
reuse and recycle;
... ...

本期配套教案共2页:  1  2

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