The objectives of this study were to compare growth of Pllioblastus pygmaed and soil characteristics as affected by difference of soil thickness and mixture ratio in shallow-extensive green roof module system, and to identify the level of soil thickness and mixture as suitable growing condition to achieve the desired plants in green roof. Different soil thickness levels were achieved under 15cm and 25cm of shallow-extensive green roof module system that was made by woody materials for 500×500×300mm. Soil mixture ratio were three types for perlit: peatmoss: leafmold=6:2:2(v/v/v, P6P2L2), perlit: peatmoss: leafmold=5:3:2(v/v/v, P5P3L2) and perlit: peatmoss: leafmold=4:4:2(v/v/v, P4P4L2 ). On June 2006, Pllioblastus pygmaed were planted directly in a green roof module system in rows. All treatment were arranged in a randomized complete block design with three replication. The results are summarized below. In term of soil characteristics, Soil acidity and electric conductivity was measured in pH 6.0∼6.6 and 0.12dS/m∼0.19dS/m, respectively. Organic matter and exchangeable cations desorption fell in the order: P4P4L2> P5P3L2> P6P2L2. P6P2L2 had higher levels of the total solid phase and liquid phase, and P4P4L2 had gas phase for three phases of soil in the 15cm and 25cm soil thickness. Although Pllioblastus pygmaed was possibled soil thickness 15cm, there was a trend towards increased soil thickness with increased leaf length, number of leaves and chlorophyll contents in 25cm. The growth response of Pllioblastus pygmaed had fine and sustain condition in order to P6P2L2 = P5P3L2 > P4P4L2. However, The results of this study suggested that plants grown under P4P4L2 appear a higher density ground covering than plants grown under P6P2L2. Collectively, our data emphasize that soil thickness for growth of Pllioblastus pygmaed were greater than soil mixture ratio in shallow-extensive green roof module system.

This study focused on the characteristics of change soil water with respect to soil thickness and soil mixture ratio, in order to effectively carry out an afforestation system for a roof with a low level of management and a light weight. Soil hardness tended to increase as sand particle was increase regardless soil thickness and soil porosity had more higher artificial soil than natural soil mixture. In case of soil pH, natural soil mixture had between 6.7 and 7.4, and artificial soil mixture had 6.0∼6.8. Organic matter, electrical conductance and exchangeable content were highest in L10, which it had the highest leafmold ratio. Soil moisture tension(kPa) in 15cm soil thickness was observed natural soil mixture had a considerable change but artificial soil mixture had a gradual change when non-rainfall kept on. In the experimental L10, S10, S7L3 and S5L5 object, the amount of moisture tended to rapidly decrease. However, in the experimental P7P1L2, P6P2L2, P5P3L2 and P4P4L2 objects, which contained pearlite and peat moss, the amount of moisture tended to gradually decrease. As a result, the use of a artificial soil mixture soil seems to be required for the afforestation of a roof for a low level of management.