Dynamics of Three Broadleaf Species in the First Five Years after Planting at Small-scale Clear-cutting

Abstract

Factors affecting the growth and survival of planted seedlings were essential information for the establishment of methods to change a coniferous plantation into conifer-broadleaved mixed forest. To reveal these factors, three deciduous trees (Castanea crenata, Cerasus jamasakura, and Quercus serrata) were planted in the different densities (1,000, 1,500, or 2,000 seedlings per ha) and methods (single tree mixed planting or single planting) in the small-scale clear-cut Hinoki cypress plantations in Hyogo Prefecture, and the growth and survival of the planted seedlings were analyzed. The canopy openness and the previous year's diameter at ground height (DGH) had a positive effect on the growth of three deciduous trees, but the soil water content had a negative effect on three deciduous trees. In terms of the survival rate, the previous year's DGH had a positive effect on three deciduous trees, and the canopy openness had a positive effect on C. crenata, and a negative effect on C. jamasakura and Q. serrata. In the single planting plot of Q. serrata, there was a large difference in the stand basal area after five years of planting among sites with different topography. In the mixed planting plot, the difference was not as large as in the single planting plot of Q. serrata, and the higher the planting density, the larger the stand basal area after five years of planting. It was suggested that the low growth and survival of seedlings could be avoided by planting multiple tree species with different response to environment, and that planting 2,000 seedlings per ha, which was the highest density among tested, was the optimal from the viewpoint of resultant stand basal area after five years of planting.