I have been watching a program about beavers on PBS and started thinking about pre-colonial era America and the unchecked consumption of land and resources. When did the notion of conservationism come into play?
Great question, and you have some good timing. Kim Heacox has a new book called John Muir and the Ice that Started a Fire, about Muir's trips to Alaska. It romanticizes Muir a bit much for my taste and has some bad information about Alaska history, but it's an easy, quick read on the topic of Muir in Alaska.
Emerson's essay "Nature" (1836) influenced Muir, as did Wordsworth, whose Lyrical Ballads influenced Emerson to write "Nature". Emerson and Muir met in 1871 at Yosemite, and Emerson introduced Muir to Thoreau's Walden.
It was Thoreau who spoke at the Lyceum Society in Concord Massachusetts and declared, "In wilderness is the preservation of the world. ... For one that comes with a pencil to sketch or sing, a thousand come with an axe or rifle."
After Muir read Thoreau, he encouraged all his friends to do so as well.
You should, too.
Muir was awesome, but it can be argued that there where folks who were interested in sustainable practices before him.
Outside the world of the European settlers, the Native Americans could easily be considered naturalists and conservators. Native cultures often live a more symbiotic lifestyle with the natural world around them.