This paper deals with the nutrient concentration and amount of understory of a deciduous broad-leaved forest at Sanbe Forest of Shimane University.
1. 38 species appeared in the understory of sampling plots and the number of individuals was 27400 per hectare. Dominant species were the following seven shrubs; Lindera umbellata, Viburnum Wrightii, Viburnum erosum, Ilex crenata, Pieris japonica, Helwingia japonica, Callicarpa japonica, and Euonymus oxyphyllus.
2. The above ground weights of shrubs were related to D^2_0H or D^2H. In estimating the above ground biomass of understory, the values were 6.69ton/ha in P-1 and 3.75 ton/ha in P-2. It was 2.0-3.2% of total above ground biomass.
3. The nutrient concentrations of shrubs were fluctuated with wide range and depended upon the difference of species and the size of trees.
4. The amounts of five nutrient elements of understory were 23.2-13.7 for N, 2.35-1.37 for P, 15.9-9.7 for K, 7.3-4.3 for Mg, and 43.6-25.7 kg/ha for Ca. The percentages of nutrient amount to total nutrient amount of above ground were about 4% for N and Ca, and 6-8% for P, K and Mg. These values were larger than that of dry matter.