不同经度天山云杉群落物种丰富度随海拔梯度变化

选择我国新疆境内天山山脉81°05′—93°415′E约12 个经度范围的昭苏、巩留、乌苏、乌鲁木齐和哈密5 个地点的天山云杉林进行垂直样带调查，分析不同经度位置天山云杉群落物种丰富度随海拔梯度的变化.结果表明：各经度的天山云杉群落是以天山云杉为优势树种的纯林，乔木和灌木种类很少，草本植物的物种丰富度主要由优势树种天山云杉控制.天山云杉在中等海拔范围分布最集中、郁闭度最大、生长最好、蓄积量最高，致使林下草本植物的物种丰富度最低.天山云杉群落草本物种丰富度随海拔梯度的变化呈山谷型曲线，可以用二次曲线方程y=ax²-bx+c(a,b,c＞0)进行描述.

Species richness patterns of Picea schrenkiana var. tianschanica communities along an altitudinal gradient at different longitudes in Xinjiang of Northwest China.

The Picea schrenkiana var. tianschanica forest in Zhaosu, Gongliu, Wusu, Urumqi and Hami that covered about 12 longitudes (81 degrees 05'-93 degrees 41.5'E) along the Tianshan Mountains was investigated by using vertical transects to analyze the species richness of the forest along an altitudinal gradient at different longitudes. The results showed that at most longitudinal positions, P. schrenkiana var. tianschanica forest was basically of pure forest, with P. schrenkiana var. tianschanica as the dominant species, very few of other arbor and shrub species, and the species richness of herbs being controlled by the growth of P. schrenkiana var. tianschanica. This forest had the widest distribution, highest canopy density, best growth, and highest stand volume at middle altitudes, resulting in the lowest species richness of herbs. The herb species richness in P. schrenkiana var. tianschanica forest in Tianshan Mountains showed an inverse hump-shaped variation along the altitude, which could be described by the quadratic equation y = ax2 - bx + c (a, b, c > 0).