I know moose in the Greater Yellowstone Ecosystem will spend the winters in the shelter of subalpine firs (just below treeline), eating the saplings that grow up around the tree when the lower branches reach the ground, and move to the next tree once they've eaten all the saplings. Apparently, this is the only place this behavior has been observed.
Anyways, obviously they are found in willowed creek bottoms and marshes, but Shiras moose are much more of a on-top-of-a-timbered-ridge kind of animal than a swamp dwelling one like their brethren to the north. I've seen them at relatively high elevations, (not that high) so who knows?