黄土高原主要造林树种的抗旱性研究

对黄土高原主要造林树种油松、侧柏、刺槐根际进行包埋处理 ,形成持续干旱环境 ,测定干旱胁迫条件下树木生理特性的变化和对树木生长的影响。结果表明 ,在相同的干旱条件下 ,侧柏的净光合速率始终大于油松 ,而蒸腾速率则相反 ;在干旱胁迫的第 2年 ,油松净光合速率比第 1年降低了 5 1.1% ,侧柏降低了 4 1.2 % ,刺槐降低了 5 4 .4 %。侧柏水分利用效率较油松高约 34%。中度水分胁迫 1年后 ,油松、侧柏、刺槐的叶量分别为对照的76 .1% ,81.7%和 79.3% ,2年后分别为 5 5 .2 % ,6 1.3%和 2 4 .2 % ,第 3年刺槐叶面积已缩小为对照的 75 % ,并出现大量落叶 ,油松、侧柏也有此现象。同时 ,持续干旱 1年后 ,油松、侧柏的枝长分别为对照的 6 4 .4 %和 6 6 .7% ;持续2年后 ,分别为对照的 37.6 %和 4 0 .9%。试验表明 ,各树种忍耐长期干旱的能力不同 ,侧柏最强 ,油松次之 ,刺槐最差 ,表明各树种林分抗旱稳定性不同。

A study of the drought resistance of the main forestation trees in Loess Platuea

The roots of Pinus tabulaeformis,Platycladus orientalis and Robinia pseudoacacia were wrapped by plastic film,then the dry environment was made.The tests showed that the photosynthetic rate of P.orientalis was higher than that of P.tabulaeformis ,but the transpiration was the opposite.After one year of treating,photosynthetic rate of P.tabulaeformis reduced 51.1%, P.orientalis 41.2%, R.pseudoacacia 54.4%.In water use efficiency, P.orientalis was about 34% higher than that of P.tabulaeformis .The leaf amounts of P.tabulaeformis,P.orientalis,R.pseudoacacia were 76.1%,81.7% and 79.3% of control.Two years later,they were 55.2%,61.3%,24.2%,and leaf areas of R.pseudoacacia were 75% of control.The lengths of branch of P.tabulaeformis and P.orientalis were 64.4% and 66.7% of control respectively after one year,and they were 37.6% and 40.9% after two years.It was showed that the drought resistance among three trees were different, P.orientalis was strongest,then was P.tabulaeformis ,the third was R.pseudoacacia .