The ramet population structures of the clonal bamboo Fargesia nitida in different canopy conditions of sulbalpine dark coniferous forest in Wolong Nature Reserve, China CLONAL GROWTH OF FARGESIA NITIDA UNDER DIFFERENT CANOPY CONDITIONS IN A SUBALPINE DARK CONIFEROUS FOREST IN WOLONG NATURE RESERVE, CHINA Gap features of subalpine dark coniferous forest in Wolong Nature Reserve STRUCTURES OF THE ARTIFICIAL MIXED FORESTS IN THE CLEAR CUT AREA OF SUBALPINE DARK CONIFEROUS FORESTS ON THE UPPER BRANCH OF THE MINJIANG RIVER