以种植于干热河谷区的赤桉（Eucalyptus camaldulensis Dehnh.）幼龄林、中龄林和成熟林为研究对象，分析了赤桉鲜叶和凋落叶中养分（包括N、P、K、Ca、Mg和Na）的含量和化学计量比，并计算各养分的再吸收率；在此基础上，对鲜叶和凋落叶中各养分的含量与再吸收率进行线性回归分析。结果表明：成熟林赤桉鲜叶和凋落叶的有机碳、全氮、全磷、全钾和全钠含量总体上高于幼龄林，而全钙和全镁含量则低于幼龄林；且鲜叶中的全氮、全磷、全钾、全钠和全镁含量总体上高于凋落叶，而有机碳和全钙含量则低于凋落叶。成熟林赤桉鲜叶和凋落叶的C∶N比、鲜叶的N∶P比和N∶K比以及凋落叶的K∶P比和Ca∶Mg比均低于幼龄林，但其鲜叶的K∶P比和Ca∶Mg比及凋落叶的N∶P比和N∶K比则高于幼龄林；且不同林龄鲜叶的C∶N比、K∶P比和Ca∶Mg比均低于凋落叶。各林龄赤桉叶的Ca再吸收率及幼龄林和中龄林叶的Na再吸收率均为负值，而其余养分的再吸收率均为正值；随林龄增长，N、K和Mg的再吸收率先升高后降低，而P、Ca和Na的再吸收率却先降低后升高；总体上看，赤桉叶中各养分的再吸收率从高到低依次为P、N、K、Mg、Na、Ca。线性回归分析结果表明：赤桉鲜叶的全钾和全钠含量分别与K和Na再吸收率呈极显著正相关（P＜0.01），全钙含量与Ca再吸收率呈显著正相关（P＜0.05）；而凋落叶的全氮含量与N再吸收率呈极显著负相关，全镁含量与Mg再吸收率呈显著负相关。综合分析结果显示：林龄对赤桉叶的养分含量和再吸收率有明显影响，其保存养分的能力随林龄增长呈现先增强后减弱的趋势。

Taking young， middle-aged and mature forests of Eucalyptus camaldulensis Dehnh. planted in arid-hot valley as research objects， contents and stoichiometric ratios of nutrients （including N， P， K， Ca， Mg and Na） in fresh and litter leaves of E. camaldulensis were analyzed， and the reabsorption rates of nutrients were calculated. On this basis， linear-regression analysis was conducted between contents and reabsorption rates of nutrients in fresh and litter leaves. The results show that contents of organic carbon， total nitrogen， total phosphorus， total potassium and total sodium in fresh and litter leaves of E. camaldulensis in mature forest are generally higher than those in young forest， while contents of total calcium and total magnesium are lower than those of young forest. Contents of total nitrogen， total phosphorus， total potassium， total sodium and total magnesium in fresh leaf are higher than those in litter leaf， while contents of organic carbon and total calcium are lower than those in litter leaf. C∶N ratio in fresh and litter leaves， N∶P and N∶K ratios in fresh leaf， and K∶P and Ca∶Mg ratios in litter leaf of mature forest are lower than those of young forest， but its K∶P and Ca∶Mg ratios in fresh leaf， and N∶P and N∶K ratios in litter leaf of mature forest are higher than those of young forest. C∶N， K∶P and Ca∶Mg ratios in fresh leaf at different stand ages are lower than those in litter leaf. Reabsorption rate of Ca in leaf of E. camaldulensis at different stand ages， and that of Na in leaf of young and middle-aged forests are negative， while that of other nutrients is positive. With increasing of stand age， reabsorption rates of N， K and Mg increase firstly and then decrease， while those of P， Ca and Na decrease firstly and then increase. In general， the order of reabsorption rate of nutrients in leaf of E. camaldulensis from high to low is P， N， K， Mg， Na， Ca. The results of linear-regression analysis show that there are extremely significantly positive correlations （P＜0.01） of total potassium and total sodium contents with reabsorption rates of K and Na， respectively， and a significantly positive correlation （P＜0.05） of total calcium content with reabsorption rate of Ca in fresh leaf of E. camaldulensis. While there is an extremely significantly negative correlation of total nitrogen content with reabsorption rate of N， and a significantly negative correlation of total magnesium content with reabsorption rate of Mg in litter leaf. The comprehensive analysis results show that stand age has an obvious effect on content and reabsorption rate of nutrients in leaf of E. camaldulensis， and its ability of preserving nutrients appears the trend of increasing firstly and then decreasing with increasing of stand age.