阿尔金山-祁连山山地植被垂直带谱分布及地学分析

Distribution and geographical analysis of altitudinal belts in the Altun-Qilian Mountains

本文揭示阿尔金-祁连山区垂直带谱空间分布模式并进行地学解释。研究表明：北坡荒漠草原带的上限具有随经度变化的二次曲线分布模式，草原带的上限分布为线性模式。亚冰雪带的分布与7月份气温的零度层分布模式基本相同；北坡镜铁山以西的带谱中没有森林带，以东含有森林带，分布在2500～3300米的高度范围内。利用气象台站的地面及高空数据，计算了湿度——生长季平均温度露点差随海拔变化的梯度、多年平均温度、1月多年均温、多年平均降水指标以解释带谱分布，结果表明：Fh东向西，湿度梯度增大，以酒泉为界，西侧的露点温度差梯度大于0．12℃／100米，东部小于0．09℃／100米，与北坡山地森林带分布基本吻合。

The Altun and Qilian mountains, situated in the northeastern edge of the Tibetan Plateau and influenced by westerly wind and monsoon and its internal atmospheric circulation, are characterized by unique vegetation zonal spectra. Zonal spectra turn out to be quite different in the southern and northern flanks, although with desert as a common base belt. Our analysis indicates that the longitudinal distribution of the montane desert steppe belt and steppe belt accord to quadratic and linear models, respectively, on the northern slopes. The distribution model of the sub-nival belt on the northern slopes is almost iden tical with that of air temperature of zero in July. Forest belts exist within the altitude of 2500 m to 3500 m a. s. 1. east of Jingtie Mountain. Meteorological observation data are used to compute air temperature and humidity indexes, including mean difference of air temperature of dew point and gradient, annual and January mean air temperature, and annual mean precipitation, so as to interpret the distribution of zonal spectra. The results indicate that humidity gradient gradually increases from less than 0. 09℃/100m to the east of Jiuquan to more than 0.12℃/100m to the west, and that vertically radical change of humidity is closely related with sparse vegetation distribution and that the sub nival belt de creasing from the east to the west and from the edge to the interior of the Plateau was caused by the climate impacts of the elevated heating over the Tibetan Plateau.