Plant species diversity in artificial Robinia pseudoacacia L. stands

Abstract

The occurrence of native plant species in nine artificial Robinia pseudoacacia L. stands (34 yrs.-94 yrs.) was evaluated in Sorachi and Ishikari regions, central Hokkaido. In the stands, total 27 tree species were found, and the maximal dbh increased with increasing stand age. The relationship between maximal dbh and stand age of native tree species did not differ significantly with that of R. pseudoacacia suggesting that the native trees invaded into the stands at the earlier stage and grew with R. pseudoacacia. On the other hand, total 43 plant species were observed on the forest floor, and the number of plant species increased significantly with increasing stand age. The number of plant species increased significantly with decreasing degree of coverage of dwarf bamboo. The degree of coverage of dwarf bamboo was significantly correlated with sum of basal area at stand level. These results imply that cover of dwarf bamboo would decline with stand growth, and the situation might allow other plant species to invade into and establish in R. pseudoacacia stands.