Abstract
For conservation of wild herb's habitat, civil engineers are required to know the ecological characteristic of every herb species which is in the habitat. We investigated the relationships between the growing densit ies of two wild herb species; Mentha arvensis var. piperascens and Elsholtzia ciliata, and several environmental conditions at the no cultivating rice field at Nagano Prefecture. As a result, the growth densities of both species were quite bigger at the shallow dip formed by running of the cultivator than on the small mound. On the mounded area, ratio of the space covered with Artemisia princeps was higher than at the dipped area. Soil moisture showed low value on the mounded area, and there was a negative correlation between ratio of soil moisture and the plant coverage of Artemisia princeps. In contrast, Elsholtzia ciliata showed a positive correlation between soil moisture. Therefore, it was considered that uneveness of the ground surface promoted growth of both species. It was suggested that the growing condition of each species can be conserved by labour-saving management
