Environmental Factor Analysis on the Growth of Planted Tree and the Establishment of Natural Seedling in Three Species of Wild Rhododendron

The environmental factor of the growth of planted tree and the establishment of natural seedling in three species of wild Rhododendron were examined on private houses of the basin of the Obitsu River and Koito River. Tree vigor of R. kiyosumense and R. dilatatum was worse than R.obtusum var. kaempfen: As a result of the analysis using quantification theory 1st family, factors of the suitable environment for R. kiyosumense were well drainage, higher altitude and loam soil. Those for R. dilatatum were well drainage, clay-loamy soil and the sun shade condition in afternoon. Those for R. obtusum var. kaempfen were the location, well drainage, and the soil acidity. Seedlingswere distributed on bryophyte with turf-typed growth form. R. kiyosumense and R. dilatatum was distributed in the halfshade condition on loamy or clay-loamy soil. R. obtusum was observed more shady condition on loamy soil.