<正>对秦岭南坡 2 3年生的华北落叶松人工林包括 0～ 60cm土层中N、P、K、Ca、Mg 5种大量营养元素的含量进行了测定 ,其总贮量达到 1 .38× 1 0 5kg hm2 ,土壤、乔木、灌木、草本和凋落物各层营养元素现存量分别为 1 .37× 1 0 5、837.85、1 71 .1 7、42 .86、348.90kg hm2 。各营养元素的积累量均为土壤库 >>植被 >枯落物层。在植被层中该林分营养元素的年吸收量、年存留量、年归还量分别为 92 .2 9、61 .93、30 .36kg (hm2 ·a)。N、P、K、Ca和Mg 5种元素的循环速率分别为 0 .82 5、0 .70 4、0 .5 0 1、0 .60 2、0 .689。与同一区域年龄相近的锐齿栎、油松、华山松林分的生物循环特征相比 ,华北落叶松人工林对土壤没有明显的不良影响。

The ecosystem of Larix principis ruppechtii Magyr forest plantation in south slope of Qinlin Mountains totally contained nutrient elements 1.38×10 5 kg/hm 2,in which the soil,arbor,shrub,grass and litter possessed nutrient elements 1.37×10 5,837.85,171.17,42.86,348.90 kg/hm 2 respectively.Distribution characteristics of nutrient elements in ecosystem of Larix principis ruppechtii forest plantation were:amounts stored by soil>>amounts stored by arbor>amounts stored by litter>amounts stored by ground vegetation.The annual uptake, store and return of the nutrient elements were 92.29 ,30.36 and 61.98 kg/hm 2 respectively.Different nutrient elements had different element return ratios.The element return ratios of N,P,K,Ca and Mg were 0.825,0.704,0.501,0.602 and 0.689 respectively.Compared with the biocycle characteristics of indigenous tree natural forest or plantation,it was found that Larix principis ruppechtii forest plantation had no obviously negative effect on soil.