Let's get together -- yeah, yeah, yeah.We environmentalists hear this periodically from friends and family and other concerned citizens: "I wish there weren't so many groups. It's confusing. I don't know who to volunteer for. Wouldn't it work better if you all got together?" This isn't quite as obvious as it sounds. Different groups have sprung up at different times to fill different niches. You wouldn't look out at a marsh and say, "It would be much nicer if there were just one kind of frog to keep track of." Diversity has some very real purposes. But there are moments …