地域环境对青藏高原特有植物藏川杨生物学特性的影响

通过对西藏中、南部16个藏川杨种源地环境特征、植株和枝叶形态特征、生长习性等生物学特性的观测比较,发现藏川杨为高大、长寿乔木,株龄逾千年、株高达45 m、冠幅22 m,分布海拔高度2000～4500 m、分布区域跨越湿润、半湿润、半干旱和干旱区,随着分布区环境变化,不同种源藏川杨的树皮、枝条、芽、叶等形态特征呈现规律性变化,空气湿度增加、树干颜色变深、枝条被毛加重、顶生冬芽变窄、叶片长/宽比增加;半湿润区和灌溉区植株的叶面积、枝条长度增加,湿润区、阴湿地或环境条件恶劣地区植株叶片和枝条生长不佳,枝条干湿比相对较小。结果表明:藏川杨具有很强的环境适应能力和可塑性,耐旱,喜光、抗强光辐射,耐贫瘠、喜中性或弱碱性土壤,具有很高的生态和经济价值。

Biological Characteristics of Populus szechuanica var.tibetica,the Rare and Endemic Plant of Qinghai-Tibetan Plateau in the Different Local Environment

Through observation and comparison about the Populus szechuanica var.tibetica’s distributing local environment,morphology of plants,branches,twigs and leaves,growth habit in the 16 distributing regions in the central and southern Tibet,it is discovered that this species is a very tall and long live tree,the age of tree being more than one thousand years with 45 m height and 22 m canopy,and distributing between the altitutes from 2000 m to 4500 m.It has different humidity in the different distributing areas,such as humid regions,semi-humid regions,semi-arid regions and arid regions.And it has some regular changes between the bark shape of the tree,surface morphologic of branches and twigs,shape of leaves and buds in the different regions.The color of the bark become darker,the twigs usually have more pubscens on the surface,the top winter buds become more narrow,and the ratio between the leaf length and wide are increased when the air humidity becomes more wetness.The area of leaf are bigger,length of twig are longer in the semi-humid regions or the places with enough irrigation.It is in a poor growth condition of leaves and branches when this species in the humid regions,shad place or very execrably environment,the ratio of dry weight and wet weight of twigs reduce.The result shows that Populus szechuanica var.tibetica has a very high ecological and economic value with its very strong adaptability and very good plasticity for the different environment stress.It has drought resistance,likes full sunshine and resistant to the very strong ray radiation,resistance to the poor soil and likes middle or alkalescent soil.