The pioneers in "Pioneers! O Pioneers!" are some seriously outdoorsy folk. Imagine flannels, work boots, and hats. Definitely hats. They don't sit around in plush chairs in fancy towns. No! They sleep on the hard ground and march across mountains and passes; they seize hold of and explore the world. This exploration also involves conquering parts of nature: felling trees, digging mines and making roads. They're not afraid to get dirty, and get the job done.
The relationship between the pioneers and the natural world is primarily antagonistic. Nature's the enemy, and it must be conquered.
Although our speaker rejoices in the felling of forests and digging of mines, he clearly appreciates wilderness. In fact, he seems to dislike places that are too civilized precisely because they don't provide the opportunity to encounter the wildness and beauty of the natural world.