[Spatial distribution pattern of Picea schrenkiana var. tianshanica population and its relationships with topographic factors in middle part of Tianshan Mountain].

By the method of point pattern analysis, this paper studied the spatial distribution patterns of different age class individuals in the Picea schrenkiana var. tianshanica forest in middle part of Tianshan Mountain and the influence of topographic factors on the distribution patterns. It was observed that the density of different age class individuals in the forest decreased with the increasing DBH of the individuals, and except old trees which presented a random distribution at the scale of 0-12 m, the saplings and the small, medium, and big trees were in aggregative distribution at all scales. With the increase of age class, the scale at which the individuals presented the highest aggregation degree increased, whereas the aggregation intensity declined. At small scale (0-16 m), different age class individuals appeared negative association, and the greater difference the tree age, the more significant the negative association presented. Altitude had significant positive effects on the number of medium, big, and old trees but had little effects on the number of saplings and small trees. Slope grade had significant positive effects on the number of saplings and small and medium trees, significant negative effects on the number of old trees, but little effects on the number of big trees. Concavo-convex had significant negative effects on the number of saplings and small and medium trees but had little effects on the number of big and old trees.