A fairly fundamentalist friend recently surprised me by admitting that he believes or is willing to believe the animist notion of dryads, naiads and other such elemental spirits that are familiar to us from Greco-Roman myth.
I admit it's an idea I've toyed with, because of stuff I've read or heard, and just because the geekboy within me finds the idea interesting and strangely compelling. I also like it because it's more nuanced than the fundamentalist view of spirits that "They're all demons."
Lewis actually discussed the notion in "That Hideous Strength," if you've read it. Merlin suggests that he can go out into the woods and glens of England and awaken the slumbering spirits he once dealt with back in the days of Arthur; and Dimble separately muses that such wild spirits could be spirits that haven't yet had to choose sides in the war between heaven and hell, or at least hadn't had to make such a decision during Merlin's time.
And of course if you're familiar with the stories missonaries tell from animist countries, there's invariably tales told of families or villages that were doing obeisance to a spirit. It wasn't an evil or malicious spirit necessarily; quite often it directed them toward good water, advised them on planting crops and so on -- and incidentally the one story I'm thinking of, from Cambodia, deals with a spirit that the family got into a relationship with after disturbing its sacred tree. Anyway, the spirits usually have a good relationship with the family until the missionaries come with the gospel and then, often though not always, the spirits go nuts and start threatening reprisals if people convert. Other times, they just fade out quietly as the family embraces the gospel.
In a larger sense, this is a reflection of what goes on when the gospel explodes in a culture where it was unfamiliar. The change the gospel brings is quite amazing: People who "get" it, who see the story as fulfilling a messianic expectation in their own culture, will see a vaues shift in terms of morals, justice and spirituality; while those who see it as a threat will start to define themselves in opposition to it. In a sense, those who have been seeking the Truth (or at least who see it) move dramatically toward it and those who prefer the secrecy of darkness move that way. The same perhaps could be said of dryads, naiads and others, for the sake of argument.
But of course, in a larger sociological perspective, we see the exact same phenomenon in conjunction with other socio-messianic movements. The music of The Beatles exploded on America like a small nuke, spiritually and socially. For large chunks of society, the 1960s was a time of redefinition, with utopian aspirations, social responsibility and breaking free of the shackles society had clapped on them. Others saw the cultural revolution spearheaded by The Beatles as a menace to society, and pushed back hard, to the point that rock music was seen as seditious, Lennon himself was regarded as a threat to national security and there was a serious move by the Nixon (?) administration to have him deported; and so on. We still see that divide perpetuated today, in the presidential campaigns, for instance, where McCain scored points with other conservatives by contrasting his service in Vietnam (establishment) with Clinton's identification with the Woodstock/hippie movement (counterculture).
So perhaps we should see "The Giving Tree" as personal revelation from the co-dependent spirits of the woods.
In the Torah, God warns the Israelites not to fall into the ways of the Canaanite people, saying repeatedly that their sins are why he is going to drive them out before the Israelites. There is another time, though, where he says "the land will vomit them out"; suggesting that this isn't just an action on his part but a reaction by the land itself, that the sin of the Canaanite peoples has so violated the natural order that the land itself was in revolt against them. In other words, sin has not just personal and interpersonal consequences, but environmental (in the broader sense than the merely ecological one) consequences as well.