In The Pioneers by James Fenimore Cooper, what is the central conflict of the story?

In Cooper's The Pioneers, the central conflict is between the the advance of "civilization," represented by the Judge Marmaduke Temple and his daughter, and the retreat of nature and Native Americans, including Natty Bumppo. At the beginning of the book, the judge, arriving on the frontier of New York state, travels with his daughter through a pristine wilderness described in the following way:

The mountain on which they were journeying was covered with pines that rose without a branch some seventy or eighty feet, and which frequently doubled that height by the addition of the tops.

In this Edenic scene, the Judge raises his fowling piece and shoots at and misses a buck who Natty Bumppo is already hunting. Later, Natty Bumppo says to the judge, "'Ah! The game is becoming hard to find, indeed, Judge, with your clearings and betterments,' said the old hunter, with a kind of compelled resignation." It is clear that whites are having a devastating effect on the land on which Natty Bumppo hunts, and it is increasingly difficult to find game.
In the novel, whites have caused environmental degradation. Around the judge's house are stumps of trees that have been destroyed, marring the purity of the scene:

Yet many a pile of snow betrayed the presence of the stump of a pine; and even, in one or two instances, unsightly remnants of trees that had been partly destroyed by fire were seen rearing their black, glistening columns twenty or thirty feet above the pure white of the snow.

The black stumps of the trees are meant to contrast with the purity and whiteness of the snow.
Later, the author describes the way in which the whites resort to overfishing on the lake:

But the slow though certain adventures with hook and line were ill suited to the profusion and impatience of the settlers. More destructive means were resorted to; and, as the season had now arrived when the bass fisheries were allowed by the provisions of the law that Judge Temple had procured.

In the law of nature that Natty Bumppo oversees, the environment is treated with care. The Native Americans only catch the fish they need. The white settlers, on the other hand, overfish and cause the ruin of the environment—all while being supported by the law. The law, personified by Judge Temple, is also a force of destruction, and Natty is jailed many times for hunting when the law does not allow it. In the end, Chingachgook (now called Indian John), Natty's friend, is killed in a forest fire, and Natty pushes further west. The law of the white frontier makes no place for Native American life and for nature.