1) Environmental regulations and property rights are frequently viewed as in conflict by the rural population, examples of government reach onto the property owner's perceived absolute rights upon their own land.
2) The view that the wilderness exists to be made use of- which, really, is a view that's quite in line with what the rural population is generally living out. Farms can look beautiful and green from the outside, but they're generally intensely managed little plots of nature, where every year is a fight against Nature's encroachment.
3) A feeling that life is hard enough in those areas and those lifestyles without further restrictions on what you can and can't do, or more work that has to happen just to keep doing the same thing that you've been doing for generations. These are generally not the people who feel like they are (or actually are!) really getting ahead in life, and anything that makes it feel like they've got to run faster on that treadmill isn't going to go over well.
I think a lot of city-dwellers idolize the wilderness, it being something that is not at all part of their daily life, to a much greater extent than the rural dwellers who can walk out into acres of forest with no one around practically whenever they feel like it.
I'm city to rural transplant who's very much conservation-minded, but it's important to acknowledge where people are coming from, too. These are certainly not the only reasons, nor are they reasons that every rural citizen is going to agree with, but they're certainly some of the reasons that I've encountered.