About ARL Research

Research Center for Ecological Application Systems

  • Ecological Systems
  • Green infrastructure management
  • Developing phytoremediation-based measures for treating heavy metal soil pollution
  • Advancing hybrid soil types for use in various artificial revegetation applications
  • Advancing hot environment relaxation effects via urban greening
  • Improving urban storm water retention and circulation via planting bases
  • Enhancing environmental real estate values by cultivating greenery

Our laboratory promotes the study, planning sciences, and technical developments needed for the formation of urban environments within which human society and ecological systems can exist in harmony. To achieve these goals, our work and study methods aim at the creation of disciplines that combine sciences related to landscape and architectural planning, environmental greenery, and the preservation and promotion of health and hygiene in various ways. Our vision calls for the integration of the natural environment into all aspects of urban land use, including disaster prevention areas such flood and fire prevention, rainwater storage and circulation, and alleviation of the heat island phenomenon and the promotion of public health issues such as environmental cleanliness and recreation. Through study and experimental investigations, we will continue to advance the public interest in the functions use of natural environments.

Research staff

  • Professor

    Center Director

    Shiro Wakui

  • Professor


    Kentaro Iijima

  • Associate Professor


    Shigehiro Yokota

Research themes

1) Heavy metal soil pollution countermeasure utilizing phytoremediation

In this experiment, Chenopodium plants were introduced to soil that was heavily polluted with lead (Pb), as shown in (Photo 1). The initial elution amounts were below the detection limit. However, over the passage of time, the amount of Pb absorbed by the Chenopodium plant roots advanced, as shown Fig. 1. Over the course of the short-term (63-day) growth experiment, the absorption amounts were 11.3 mg/kg for a 50 mg/kg section, 53.3 mg/kg for a 150 mg/kg section, and 134.3 mg/kg for a 500 mg/kg section.

During the long-term (115-day) growth period, Pb measurement values in the analyzed plant roots were initially below the detection limit of 17.3 mg/kg for a 50 mg/kg section, 79.7 mg/kg for a 150 mg/kg section, and 262.0 mg/kg for a 500 mg/kg section. However, as the growth period progressed, the Pb content increased and the absorbed amounts could be measured in the leaves and stems of the plants, as shown in Fig. 2.

The control and 50 mg/kg section was below the detection limit of 21.3 mg/kg of 150 mg/kg section and 54.0 mg/kg of 500 mg/kg section in the leaves and stems of the plants analyzed during the short-term (63-day) growth period. Next, we found that the control and 50 mg/kg section was below the detection limit, 16.0 mg/kg of 150 mg/kg section, and 33.7 mg/kg of 500 mg/kg section in leaves and stems of plants analyzed after long-term (115-day) growth periods. The content differences were not reflected in the vegetation growth periods.

Photo 1: Chenopodium growth
Fig. 1: Absorbed Pb amounts in roots
Fig. 2: Absorbed Pb amounts in leaves and stems

2) Study on hot environment relaxation effect brought about by railway track greening

In these experiments, we attempted to influence the heat island effect by introducing greenery to railway track beds. The results of the experiment (shown below) indicate that the introduction of greenery resulted in lower railway bed temperatures for all periods over the course of a day, except for mornings during which rainfall occurred. It could also be seen that the temperature values were lower up to 100 mm above the ground surface. Furthermore, the temperature of the greening section continued to be low at night. When comparing the cooling effect on the vicinity of the ground surface, we found that a cooling effect of 330 minutes could be confirmed for the greening section and 220 minutes at 100 mm above the ground, as shown in Fig. 1. Both the ground surface and the measured value at a height of 100 mm showed that the greening section stayed cooler longer than the non-green section. Figure 2 shows a thermography photograph of the green and non-green railbeds measured in our experiment. An analysis of those images showed that the green plot was 7.2 degrees lower than the asphalt section and 4.4 degrees lower than the non-green section on a day when the environmental temperature at 12:00 noon was 38.7 degrees.

Fig. 1: Cooling effect by track Greenery
Fig. 2: Thermography of urban greenery