Why is it considered "liberal" to conserve and "conservative" to be profligate?

Living in the "Conservative south" I know many conservatives do not want to see pollution or planetary dimise, however their arguement is that being forced to buy a certian lightbulb, or use a specific product is an infringement on freedom of personal choice. The flaw with Conservative thinking is that at one time in our nation's history the number of people living here allowed for such free choices, now population strains on the environment are cause for unfortunate regulation. I see both sides of the issue, no one wants to be told what to do yet if we are to sustain our population we must observe a new way to live.