@caichongjun
Are forests important because of their values?
I don't know what you mean by “values” in this context, but in my opinion forests are valuable mostly as incredible biodiversity reservoirs harboring thousands or millions of different species of plants and animals.
They also help prevent erosion, flooding, mudslides and other negative effects of rainfall, while contributing in important ways to a healthy water cycle.
If managed properly, they can also represent a great source of wealth, but only if the harvesting of resources is done responsibly and conservatively.