Effects of Tending Practices of Multi Storied and a Mixed Stands on Chemical Properties of Forest Soils

据调查，在宿木下30~40岁以上的土壤中，钙等盐基在上层迅速增加，交换性钙积累层向下层移动。此外，杉木林下土壤中N、P的积累和土壤pH的增加是明显的，而Hinoki和阔叶林下的土壤中N、P的积累和土壤pH的增加则不明显。这些结果表明，多层混交林和含有Sugi的混交林提高了土壤肥力。多层混交林和混交林对土壤肥力的影响因杉木混交状态和保留杉木林分密度的不同而不同，这一假设得到了证实。主要研究结果如下：(1)在？木县和岩手县选择了6个杉木与新诺木、赤松与阔叶树混交林。在杉木林密度较高的混交林中，A0层的干重和N、P、K、Ca等营养元素的含量高于其他林分。矿质土壤中交换性钙、磷含量增加，土壤pH升高。这些特征在低碱度饱和度的安多斯土上表现得尤为明显。(2)在赤木、千叶和岐阜县选择了8个多层林分。上部树种由杉木、山木和阔叶树组成，林下树龄均小于30年。在树龄超过40年的杉木上层林分中，A0层的干重和N、P、Ca等养分元素的含量均高于Hinoki和阔叶树。这些营养物质在矿物质中增加。这些特征在低碱饱和度的红壤和粗碎块含量低的土壤中表现得尤为明显。

According to out investigation, in the soils beneath Sugi stands more than 30 to 40 years olds, Ca and other base has increased repidly at the upper layr, and the layr of exchangeable Ca accumulation moves to the lower layr. In addition, the accumulation of N and P and an increase in soil pH were evident in the soils beneath Sugi stands, but not in the Hinoki and broad leaved stands. These results suggested that the multi storied and the mixed stands containing Sugi increase soil fertility. While the effect of a multi storied and a mixed stands on soil fertility differed according to the mixed state of Sugi and the stand density of reserved Sugi, the above presumption was confirmed. The results obtained were as follows.(1) Six mixed stands of Sugi with Hinoki and of Akamatsu with broad leaved trees were chosen in Tochigi and Iwate Prefecture. In the mixed stands with the high stand density of Sugi, the dry weight and the contents of nutrrents such as N, P, K and Ca of A_0 horizon were abundant compared to the other stands. In mineral forizon also, exchangeable Ca and P have increased and soil pH rose. These characteristics was obvious in Andosols with low base-saturation.(2) Eight multi storied stands were chosen in Tochigi, Chiba and Gifu Prefecture. Upper trees were consisted of Sugi, Hinoki and broad leaved trees, the age of Sugi or Hinoki underplanted was less than 30 years olds. In stands which upper trees are Sugi and more than 40 years old, the dry weight and the contents of nutrients such as N, P, Ca of A_0 horizon were abundant compare to Hinoki and broad leaved trees. These nutrients increased in mineral horiaon. These characteristics was obvious in Andsols with low base-saturation and in soils with the low content of coarse fragment.