Yes,gaslest, many alpines are succulents. They have evolved that way to conserve moisture which is unavailable to them when it is frozen as ice or snow, but they do contain chemicals in their cells which act as anti-freeze, whereas succulents from arid regions do not have such antifreeze so frost can kill them. Sempervivums and sedums will survive the winter here but things like aoniums and graptopetalums need some protection. better to be safe than sorry but, if in doubt, look up the natural habitat of your plant and try to replicate it.