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一圆柏属(Sabina)是从温带森林中分化出来的最早化的类型。由于叶形小,半肉质,蒸腾弱,很适应于第三纪亚洲中部的干热气候,因之能够在山地得到扩展。同时在旱化过程中,使得生长速度降低,树干致密坚硬,枝条柔韧,根系发达,增强了抗风能力。到了第四纪,冰期来临,高原上升,气候激烈动荡,圆柏属的某些种又在适应当时环境的演化中,获得了极为耐寒的特性。正是由于这个类群的耐旱耐寒抗风,所以成为今日青藏高原森林地带的重要组成树种之一,其中有些种且伸入到高寒地带,广布于
A Sabina is the earliest type of differentiation from temperate forests. Due to its small leaf shape, semi-fleshy and low transpiration, it is suitable for dry and hot climates in the middle of Central Asia in the Tertiary. It can therefore be extended in the mountains. At the same time in the process of drought, making the growth rate is reduced, dense and rigid trunk, branches flexible, developed root system, enhanced wind resistance. In Quaternary, the advent of the ice age, the rising of the plateau and the intense and turbulent climate, some species of Juniperus are extremely cold-tolerant in adapting to the evolution of the environment at that time. It is because of this group of drought-resistant, cold-resistant and wind-resistant, so it has become one of the important tree species in the forest zone of the Qinghai-Tibet Plateau today, some of which extend into the alpine zone,