I do not know where you get your information but it is so far off I do not understand. The Native Americans of the Northeast and Southeast did not do what you said. What little clearing the did was minimal and does even compare to the agricultural practices of the Europeans that came to america. The forest of northern europe prior to christianity was so dense it protected the germanic tribes. The buffalo, ranged through pennsylvania were wiped out by the europeans. The north american forest were so thick with vegetation which the Native Americans lived in. As Europeans moved west the cleared most of the forests which lead to erosions. I do not know were you are getting your information but it is so far from the truth that it is concerning that is unless it is Christian propaganda to rewrite history again. The proto orthodox christians rewrote history from the beginning to make it look that their way was the correct way from the beginning of Christianity even though factual evidence shows it was not. Christians rewrote history about the pagan to eliminate them form Europe with horrible propaganda which was not true the murdered men women and children. Burned people alive. slaughtered whole tribes of people who were unarmed just because they wanted to believe it their faith. I guess they were pagan martyrs for God.
I'm getting my information from professors (I took a number of courses on Native American history, and history in general, which was my minor), scholarly papers that were published in peer viewed journals, a number of books by scholars in the field, and the like. What I am saying is not that far off.
One of the fallacies that are using is that since one group did things to a larger extent, or worse extent, what others have done is not wrong. That simply does not make sense. You can't justify one person's wrong doings by saying that others have done it on a larger scale.
Now, looking at hunting animals, while it is true that Europeans did wipe out large quantities of buffalo, to the point of near extinction. There are other animals that have suffered the same fate. There is no denying that. There should also be no denying that early Native Americans also wiped out, to the point of extinction, a number of different large mammals. These included mammoths, mastodons, giant sloths, bear-sized beavers, camels, lions, horses, and many other large mammals. They are now all extinct. Archeological records show that these animals were hunted in mass numbers. The evidence for this are the large kills pits that have been found, with massive numbers of bones from these animals, many of which still have the weapon tips impaled in the rib bones. (Michael Shermer, in his book, Borderlands of Science, discusses this on his chapter called the Beautiful People Myth)
The view of North America that you point to, at the time of European arrival, is actually the European "Christian" view. The idea that when Europeans arrived in North American, that it was this pristine forest, is a myth that European "Christians" propagated based on their views of nature. In William M. Denevan's The Pristine Myth: The Landscape of the Americans in 1492,
he shows how Native Americans had already modified the forest, expanded and even created grasslands, as well as changed the composition of the forests. Ecologists now believe that if it was not for the annual burning of grasslands, the western prairies would have vanished. By the time of European arrival, much of the mature forest was open, because of burning and clearing. And it is no wonder that the land did experience so much change because of the millions of people who inhabited North America pre 1492. It is because of this open forest that Europeans were able to spread through it so quickly.
And looking at Chaco Canyon in specific (this is the area that I actually focused a study on), the environmental destruction is clear, as I pointed out before (if you want more, Jared Diamond, in his book Collapse shows this even more. He also goes over the destruction done by the Norse in Greenland, as well as other ancient ecocide). Going to Chaco Canyon today, what is left is nothing but a desert, where a once dense juniper forest had thrived. And in fact, it is a clear example of Native Americans clearing the land to such an extent that the erosion was so devastating, that any sort of irrigation became impossible. Any form of agriculture was impossible.
This isn't Christian propaganda. The idea of the dense forest that you are talking about is in fact the European "Christian" view.
Also, pagans are also guilty of slaughtering entire groups for one reason or another. The amount of violence in the United States before Europeans came here. In fact, it was part of some of the various Native Americans societies and religions. When Europeans were settling here, in the Northeast, there was common warfare among the various tribes. In fact, that is part of the reason why some Native Americans accepted European friendship, as it was one more ally for them.