Abstract
Riverbank construction is usually accompanied by revegetation of bare soil using block sodding of a single species. With the aim of developing a technique for introducing several species simultaneously, we performed a 1-year experiment to clarify the initial effect of block sodding of turf in two soil types and different sowing densities on the restoration of species representing semi-natural grasslands. Cirsium oligophyllum (Franch. et Sav.) Matsum., Adenophora triphylla (Thunb.) A. DC. var. japonica (Regel) H. Hara, Aster iinumae Kitam. ex Hara, and Salvia japonica Thunb. were sown in the joints of turf in experimental trays. Germination rates differed markedly among species. Significant positive effects of block sodding were observed in terms of the germination rate of C. oligophyllum and A. iinumae individuals at the seedling stage, whereas subsequent competition with turf increased the risk of mortality of established individuals. Soil from arable fields resulted in lower survival rates of C. oligophyllum and A. iinumae than that collected from riverbanks. Survival rate of C. oligophyllum was negatively significantly associated with sowing densities.
