The aim of present study is to elucidate the effects of manganese and aluminium ions on the germination and seedling growth of Pinus banksiana and Alnus tinctoria and to estimate the limiting level of those ions in the cultivated soils. The rate of germination of Pinus banksiana was increased under the relatively low concentration of Mn and Al (100 p.p.m), however, the germinating activity was not affected. High concentration over 110 p.p.m. of Mn and Al was related to the reduced percentage of germination and seedling growth of Pinus banksiana and Alnus tinctoria. Soils sampled from various parts of Korea contained Mn as much as high level that would be harmful for the seedling growth of Pinus banksiana and Alnus tinctoria.