Any person who is out to save "mother earth". Usually, these people come in the form of hippies, bunny lovers, and tree huggers. Nature extremists. They hate SUV's, any type of offroad vehicles (i.e. dirtbikes, quads), and dune buggies. If it means we can't build a house because it'll take away the habitat of a fucking tree frog, they're all for it. They're usually jobless and "live off of nature". Sometimes they're referred to as "homeless". Except for the rare ones like Al Gore.
We can't go trailriding because those tree hugging, bunny thumping, nature nazi's were whining that they saw a screach owl in the woods and we might give it a heart attack and cause it to become extinct.