Is there bias in 1491 by Charles C. Mann?

In a 2002 article in the Atlantic Monthly, Charles Mann alludes to his bias in his book 1491.

In that book, Mann makes a fascinating argument. While the early European settlers of the New World, such as the Pilgrims, thought they were entering a pristine or untouched wilderness, Mann argues that in both North and South America, Native Americans had been cultivating and managing the environment for a very long time. The Europeans simply did not understand this because Native land management did not look like the way they cultivated their land—or the Europeans did not want to understand this, because it was more convenient to treat the land as wilderness. Mann points out the large fires the Indians set to clear land as an example of managing the environment. He also argues that the Indians were more advanced than the Europeans in understanding agriculture, which is why the Europeans made Native crops, such as the potato, staples in their own cultures.

Because of this research, Mann is biased against letting land simply return to wilderness, which he says has led to an outcry in some environmental circles. Mann writes, however, that the land must be managed:

Guided by the pristine myth, mainstream environmentalists want to preserve as much of the world’s land as possible in a putatively intact state. But “intact,” if the new research is correct, means “run by human beings for human purposes.” Environmentalists dislike this, because it seems to mean that anything goes. In a sense they are correct. Native Americans managed the continent as they saw fit. Modern nations must do the same.