close, and kudos for earnestly attempting to answer. Here's the mission from the USFS brochure
The mission of the US Forest Service (USFS) is to sustain the health, diversity, and productivity of the Nation's forests and grasslands to meet the needs of present and future generations.
That's cool, I did not know about their mission statement. But I do know about the Organic Act of 1897, which is still the basis of the existence of the USFS, which states its own purpose, to remove all doubt:
"Public forest reservations are established to protect and improve the forests for the purpose of securing a permanent supply of timber for the people"
The mission of the US Forest Service (USFS) is to sustain the health, diversity, and productivity of the Nation's forests and grasslands to meet the needs of present and future generations.