Altitudinal distribution rule of Picea schrenkiana forest’s soil organic carbon and its influencing factors VERTICAL ZONE SPECTRUM OF VEGETATION IN FOPING NATIONAL RESERVE AND THE COMPARISON WITH THE ADJACENT AREAS THE BASIC FEATURES OF VEGETATION OF FOPING NATURE CONSERVATION IN SHAANXI PROVINCE VERTICAL ZONES OF BRYOPHYTES IN GUANCEN MOUNTAINS FOREST AREA IN SHANXI PROVINCE