华北落叶松人工林叶内营养元素含量的变异

The variation of nutrient contents in needles of prince rupprecht′s larch plantation

通过固定标准木、定期采样和化学测定, 分析了华北落叶松人工林叶内营养元素含量随冠向、冠层和生长季节的变化而变化规律 结果表明: 叶的营养元素含量在不同冠向间有一定的差异, 但差异不显著不同冠层间叶的营养元素含量变化有一定的规律, N、P、K由树冠底部到树冠顶部是逐渐增加的, Ca则是逐渐减小, Mg的变化无一定规律 方差分析表明林木不同冠层的N、P、K、Mg含量差异不显著, Ca的含量则差异显著 树冠各层次针叶营养元素含量的平均值与树冠中部针叶的营养元素含量很接近, 建议进行营养元素概算以树冠中部的针叶为样品 华北落叶松人工林叶的营养元素含量随季节的变化而呈现有规律的变化 刚展叶的华北落叶松N、P、K、Mg含量很高, 展叶期明显下降, 之后随季节的变化逐渐下降, 落叶前期显著下降; Ca的含量随季节变化相反, 刚展叶含量很低, 随季节变化一直呈上升趋势, 落叶前达峰值 根据叶的营养元素含量的季节动态和变异规律, 确定的最佳采样时间为7。

Variation in nutrient contents of needles with crown directions,crown layers and seasons in prince rupprecht′s larch plantation in south slope of Qinling Mountains have been studied by fixed sample tree, periodical sample and chemical analysis. Although the contents of N,P and K in leaves decreased from top to base of the crown, whereas the content of Ca increased. The contents of N,P,K and Mg in leaves decreased gradually with needles age whereas the content of Ca increased and reached summit before falling leaves. According to variation in nutrient contents of needles with crown directions, crown layers and seasons,the middle part and south direction of crown during July and Aug. were suggested as suitable sample position and time respectively.