每年的3月12日为植树节，植树节是为了保护倡导人民种植树木，鼓励人民爱护树木，提醒人民重视树木。树木对于人类的生存，对于地球的生态环境，都是起着非常重要的作用。
Did you know that algae and trees were the first forms of life on Earth five million years ago?
It was because they produced oxygen that human beings could evolve so quickly.
Today there are billions of people inhabiting our planet, and our living environment has undergone many changes.
Do we still need trees?
Absolutely!
After all, the algae in the oceans and the trees on land produce the largest percentage of oxygen on earth.
And we can't live without oxygen.
They also absorb CO2 from the air.
This is a good thing because the increasing emission of greenhouse gases is releasing so much CO2 into the atmosphere that the result is an acceleration of global warming.
By absorbing CO2, trees are slowing this process immediately.
