What does Aldo Leopald mean when he writes "To see America as history..."

In Aldo Leopald's speech, "On a Monument to a Pigeon", which commemorates the extinction of the passenger pigeon, he ends the speech with this:

"To see America as history, to conceive of destiny as a becoming, to smell a hickory tree through the still lapse of the ages---all these things are possible for us, and to achieve them takes only the free sky and the will to ply our wings."

What does he mean? Is something like, "We should learn from American's mistakes and value the lost wilderness of frontier America"? Is the destiny part a reference to Manifest Destiny?

Please, can someone help me? It is very hard to find study help for this piece from the Internet. Thank you!