Ecological studies on the self fertilization effects of trees.

森林的初级生产力取决于树木和环境之间的养分循环。在这些养分循环中，凋落物是养分进入土壤的重要流量，树木从土壤中吸收养分。枯枝落叶引起的养分循环被称为“树木的自肥效应”。在整个研究期间，对京都的两个人工林，即钝顶乔木人工林和柳杉人工林的养分循环进行了研究，结果如下：1.对生长在两种不同土壤条件下的两个人工林的凋落物供应进行了为期两年的测量。2.两个人工林土壤呼吸速率的季节变化在两年的时间里被测量，两个人工林的年总二氧化碳释放量相似。3.测定了两个人工林针叶养分含量的季节变化。4.两个人工林针叶凋落物的分解过程被跟踪了两年多，养分的释放很大程度上取决于土壤的营养条件。5.在两年的时间里，氮素矿化过程有明显的季节性变化，柳杉林的氮矿化潜力明显较高。

Primary productivities of forests depend upon the nutrient cycling between trees and environments. In these nutrients cycles, the litter fall is an important flux of nutrients into the soil, from where trees absorb the nutrients. The nutrient cycle by litter fall has been termed "the self fertilization effects of trees".Nutrient cyclings were studied in two plantation forests, i.e. Chamaecyparis obtuse and Cryptomeria japonica plantations in Kyoto and the following results were obtained through the study period. 1. Litter fall supplies were measured in the two plantations growing on two different soil conditions, over a two year period. 2. Seasonal changes in soil respiration rates were measured in the two plantations over a two year period and the total annual carbon dioxide evolution was similar between the two plantations. 3. Seasonal changes in nutrient contents of needles were measured over a two year period in the two plantations. 4. Decomposition processes of needle litter were followed over a two year period in the two plantations, and nutrients release largely depended upon the soil nutritional conditions. 5. Seasonal changes in nitrogen mineralization processes were followed over a two year period and the mineralization potentials were significantly higher in the Crypromeria forests.