北京人工刺槐林化学元素含量特征

 31年生人工刺槐(Robinia pseudoacacia)林内各种植物的化学元素含量以C素最高，尤以刺槐树干中C含量多。N和Ca在刺槐叶片中含量大。丛生隐子草(Cleistogenes caespitosa)地上部分含K量高于林内其他植物。Fe在荆条(Vitex negundo var．heterophylla)叶片中含量较多。Al和Na在植物细根中含量为大。酸枣(Zizyphus jujuba var．spinosa) 叶中含有较高的Mg和Mn。 刺槐林的乔木、灌木、草本层化学元素积累量以C>Ca>N> K>Mg>P>Fe>Al>Na>Mn>Cu>Zn为序。灌木层化学元素积累量除C和Ca以外，均高于乔木层。对比地表枯枝落叶层化学元素总量与人工林元素的积累量，以Na的比值最高，Ca、Mn、Fe、Zn比值次之，元素归还量都较大。P比值较低，归还量较少。刺槐林土壤化学元素贮存量是以Ca>N>Mg>Fe>K>P>Na>Mn>Al>Zn>Cu为序。植物对土壤中化学元素的富集系数以K、Al和P较高。人工林元素积累量与土壤元素贮存量之比，亦以K、P、Al比值较高。可见土壤中的K、P和Al相对是不足的。

THE CONTENTS OF CHEMICAL ELEMENTS IN ROBINIA PSEUDOACACIA PLANTATION IN BEIJING

C is found to be the most abundant element in the various plants of 31-aged Robinia pseudoacacia plantation, especially in the trunk of Robinia. The leaf of Robinia has high contents of N and Ca. K in the above-ground part of Cleistogenes caespitosa is very plentiful. The leaf of Vitex negundo var. heterophylla has much Fe. The small roots of plants are rich in Al and Na. The leaves of Zizyphus jujuba var.spinosa contain more Mg and Mn.The accumulation of chemical elements in various layers of the plantation decreases in the order Of C>Ca>N>K>Mg>P>Fe>Al>Na>Mn>Cu>Zn. The accumulation of different elements in the shrub layer is higer than those in the tree layer except C and Ca. Comparing the amount of elements in litter with which in plantation, the ratio of Na is the highest one with the higher ratio of Ca, Mn, Fe, Zn. These elements will gradually return to the soil. The ratio of P is lower, less P from litter will return to soil. The sequence of Ca>N>Mg>Fe>K>P>Na,Mn>Al>Zn>Cu is shown in soil nutrient pool. The concentration ratio of K, Al, P between plant and soil is significant. The ratio of accumulations of K, P, Al in plantation to those in soil nutrient pool is also higher. The content of K, P, Al in the soil is relatively not abundant.