Distribution patterns of Picea schrenkiana var. tianschanica population in Tianshan Mountains
A vertical transect investigation on Picea schrenkiana var. tianschanica forests was conducted at five different longitudinal sites (Zhaosu, Gongliu, Wusu, Urumqi, and Hami) in Tianshah Mountains, and the distribution pattern of P. schrenkiana var. tianschanica population at each site was analyzed based on theoretical distribution model and aggregation intensity index. On the whole, the P. schrenkiana var. tianschanica population in Tianshan Mountains presented a clumped distribution, and the distribution pattern and clustering intensity were affected by the developmental stages of stem and the ranges of altitude to some degree. The clustering intensity increased with the increasing size (DBH) or developmental stage of stem, and had the highest values at high altitudes.