moss-covered hornbeam trunk. humid subtropics of colchis between the caucasus and the black sea

air april belt black brium bryales bush caucasus changeabl colchis cold cover disturbed early epiphytes fall fickle first forest freeze frost green hornbeam humid instable late life moss mosscovered mosses period plant prewinter sea season shower snow snowcovered south subtropical subtropics sudden transition transitional treacherous tree true trunk unexpected unsettled variable weather winter wintertime zone