干热河谷纯林和混交林下印楝养分特征

Nutrient Content Characteristics of Azadirachta indica in Pure and Mixed Plantations in Arid-Hot Valley

为了更好地指导干热河谷不同恢复模式下人工林经营过程中的养分管理以及造林树种和造林模式的筛选,以元谋干热河谷印楝(Azadirachta indica)纯林及印楝×大叶相思(Acacia auriculiformis)混交林为研究对象,对林地土壤、印楝各器官5种主要元素(N、P、K、Ca、Mg)养分质量分数进行了对比研究。结果表明:印楝混交林内土壤全N、全P、全K及其速效养分质量分数均显著高于纯林(P<0.05);纯林和混交林内印楝各器官5种养分元素总量大小顺序发生了改变,纯林内为叶>枝>皮>根>干,混交林内为叶>皮>根>枝>干;纯林内印楝各器官(除干外)N、P质量分数均低于混交林,且叶内N/P比(8.0)较混交林(11.1)小,显示对N素的缺乏;元谋干热河谷印楝养分富集系数较高,印楝可能通过奢侈吸收提高植物体内养分含量来适应干热河谷土壤贫瘠环境。

A comparative study was performed to analyze contents of nutrient elements （ N, P, K, Ca, Mg） in soil and organs of Azadirachta indica in a pure plantation and a mixed plantation with Acacia auriculiformis in Yuanmou arid-hot valley, aiming to provide references for nutrient management for different restoration patterns of plantations in arid-hot valleys and selection of appropriate reforestation species and patterns. Results showed that the contents of soil total and available N, P and K in the mixed plantation were significantly higher （ at the 0.05 level） than those in the pure plantation. The total nutrient content in the leaves of A. indica was the highest in the pure plantation, followed by branch, bark, roots and stem. However, the total nutrient content in the leaves was the highest in the mixed plantation, followed by bark, roots, branch and stem. The contents of N and P in each organ in addition to stem as well as N/P ratio （8.0） in the leaves ofA. indica in the pure plantation were lower than those in the mixed plantation, indicating a scarcity of N for A. indica in the pure plantation. The accumulation coefficient of nutrients in A. indica was higher in Yuanmou arid-hot valley, which indicated that A. indica could enhance its nutrient content by luxurious absorption to adapt to barren soils.