The ocean pulls us to its edge with a primeval force. Toes in the sand, face caressed by sea breezes, we worship the beach as the symbol of idleness and renewal. But as a habitat, the beach is no picnic. The sand we so blissfully let slip through our fingers is nutrient poor, doesn't hold water and is constantly shifting. Winds can be battering. And as anyone who has salted a driveway for snow and ice knows, salt can have a withering effect on plants.