干热河谷几种典型造林树种的水分利用效率研究

干热河谷地区造林成活率低一直是困扰国内学者的难题之一，其中影响其成活的关键因子之一就是土壤水分。进行科学合理的节水灌溉就显得十分必要。相思适宜的土壤含水率（SWC）范围为12％～24％；合欢适宜的土壤含水率（SWC）范围为12％～28％；车桑子适宜的土壤含水率（SWC）范围为10％～26％。在此范围内，水分利用效率较高，光合速率水平也不低，林木能进行正常的生长及结实，不影响产量。植物的抗旱性与水分利用效率没有相关关系。植物的抗旱性强弱与其本身的形态、抗性生理生态特性有关。就本文中所涉及的几个指标来说，得出植物的抗旱性强弱顺序为：新银合欢（Leucaena sp．）〈车桑子（Dodonaea viscose）〈赤桉（Eucalyptus camaldulensis）〈台湾相思（Acacia confusa）；而水分利用效率的顺序则是：相思〈车桑子=桉树〈合欢。

A Study on Water Usage Efficiency of some kinds of Afforestation Trees in Dry and Hot River Volley

Low afforestation survival rate in dry and hot river volley area is always one of difficult problems that perplex domestic scholars. One of the key factors that effect tree survival is soil water. Adaptive drought had some fixed positive function on enhancing WUE The adaptive SWC range of Acacia confusa and Leucaena sp. and Dodonaea viscose were respectively 12 %- 24% ,12%-28% and 10%-26% ; in this range WUE was high,Pn was not low. Trees could go on normal growth and fruitage and their productivity was not bad. Plant drought-resistance had relations with plant form, resistant physiological and ecological property. The plant that had strong drought resistance didn＇t always has high WUE and contrariwise. As for some indexes in the essay, the drought-resistant order was： Leucaena sp. 〈 Dodonaea viscose 〈Eucalyptus camaldulensis 〈 Acacia eonfusa. In dry and hot river volley area,when choosing afforestation trees,drought resistance and WUE should be combined.