元谋干热河谷相思树种和桉树类抗旱能力分析

对元谋干热河谷引种的8种外来树种进行了抗旱性分析，发现水分利用效率从高到低的顺序依次是：窿缘桉、赤桉、柠檬桉、绢毛相思、肯氏相思、厚荚相思、大叶相思、马占相思。水分利用效率越高，对干热环境的适应性越强。8种外来树种适应干热河谷生境的旱性结构的特点是主根深、侧根多、栅栏组织和贮水组织发达、构成等面叶或近等面叶。桉树类树种的蒸腾速率较高，但能生存的主要机理根系分布深，主动供水能力强，补充了地上部分的水分消耗；而相思类则以发达的根系和较高的叶片保水能力来适应干热环境。

The Drought Resistance of Acacia and Eucalyptus in Yuanmou Dry-hot Valley Yunnan Province

Eight exotic species were tested in terms of drought resistance in Yuanmou dry hot valley. The order of water use efficiency (WUE) was:Eucalyptus exserta>E. camaldulensis>E.citriodora>Acacia holosericea>A. cunning>A. crassicarpa>A. auriculiformis>A.mangium. The higher WUE implies the better the drought resistance and the adaptation to dry hot environment. The anatomical structure observation showed that the characteristics of the adaptation xeromorphic structure of eight species in dry hot valley were: deep main roots, developed lateral roots, thick leaves, well developed palisade tissue and degenerated spongy tissue, well developed water storing tissue, isolateral leaf were important characteristics of xeromorphic structure. The survival mechanism of Eucalyptus with high transpiration rate in dry hot valley is for their deep root system that can actively supply water to the leaves. The well developed root system and high water holding capacity of leaves enable Acacia to adapt the dry hot environment.