• Horticultural Science & Technology
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• v.31 no.4
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• pp.503-511
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• 2013

The purpose of this study was to evaluate temperature reduction and heat budget of extensive modular green roof planted with Sedum sarmentosum and Zoysia japonica. Plant height and green coverage were measured as plant growth. Temperature, net radiation and evapotranspiration of concrete surface, green roof surface, in-soil and bottom were measured from August 2 to August 3, 2012 (48 hours). On 3 P.M., August 3, 2012, when air temperature was the highest ($34.6^{\circ}C$), concrete surface temperature was highest ($57.5^{\circ}C$), followed by surface temperature of Sedum sarmentosum ($40.1^{\circ}C$) and Zoysia japonica ($38.3^{\circ}C$), which proved temperature reduction effect of green roof. Temperature reduction effect of green roof was also shown inside green roof soil, and bottom of green roof. It was found that Zoysia japonica was more effective in temperature reduction than Sedum sarmentosum. Compared with the case of concrete surface, the highest temperature of green roof surface was observed approximately 2 hours delayed. Plant species, temperature and soil moisture were found to have impact on surface temperature reduction. Plant species, air temperature, soil moisture and green roof surface temperature were found to have impact on temperature reduction in green roof bottom. As results of heat budget analysis, sensible heat was highest on concrete surface and was found to be reduced by green roof. Latent heat flux of Zoysia japonica was higher than that of Sedum sarmentosum, which implied that Zoysia japonica was more effective to improve thermal environment for green roof than Sedum sarmentosum.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.6
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• pp.190-197
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• 2012

The purpose of this study was to evaluate thermal environment and heat budget of light thin layer green roof through an experiment in order to quantify its heat budget. Two concrete model boxes($1.2m(W){\times}1.2m(D){\times}1.0m(H)$) were constructed: One experiment box with Zoysia japonica planted on substrate depth of 10cm and one control box without any plant. Between June 6th and 7th, 2012, outside climatic conditions(air temperature, relative humidity, wind direction, wind speed), evapotranspiration, surface and ceiling temperature, heat flux, and heat budget of the boxes were measured. Daily maximum temperature of those two days was $29.4^{\circ}C$ and $30^{\circ}C$, and daily evapotranspiration was $2,686.1g/m^2$ and $3,312.8g/m^2$, respectively. It was found that evapotranspiration increased as the quantity of solar radiation increased. A surface and ceiling temperature of those two boxes was compared when outside air temperature was the greatest. and control box showed a greater temperature in both cases. Thus it was found that green roof was effective in reducing temperature. As results of heat budget analysis, heat budget of a green roof showed a greater proportion of net radiation and latent heat while heat budget of the control box showed a greater proportion of sensible heat and conduction heat. The significance of this study was to analyze heat budget of green roof temperature reduction. As substrate depth and types, species and seasonal changes may have influences on temperature reduction of green roof, further study is necessary.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.4
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• pp.127-134
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• 2012

This study was carried out to suggest an experimental base in selecting the cold tolerance of plants. The cold tolerance of the plants were subject to laboratory low temperature treatments and cold processing time were evaluated using both electrolyte leakage and regrowth test. The Logistic model of nonlinear regression analysis was used to evaluate the lethal temperatures that were predicted with the range of $-16.1{\sim}-24.4^{\circ}C$. The order of low-temperature resistance was Sedum reflexum > S. spurium > Ophiopogon japonicus > S. album > S. takevimense > Dianthus chinensis. At the lowest temperature of $13.4^{\circ}C$ the electrolyte leakage value of the plants were lower than 50% demonstrating that they could be applied stably to the roof installed in Korea during the winter with the lowest temperature of $-13.5^{\circ}C$.

• Journal of the Korean Institute of Landscape Architecture
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• v.40 no.6
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• pp.180-189
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• 2012

This study was carried out to suggest an experiment based for selecting Sedum, which can adapt well with heat tolerance in extensive green roof system. The heat tolerance of Sedum subject to laboratory high temperature treatment and heat processing time were evaluated using electrolyte leakage, chlorophyll content and regrowth test, and the relation between soil water content and heat tolerance were researched. Logistic model of nonlinear regression analysis was used to evaluate the lethal temperatures that were predicted with the range of $45.0{\sim}48.1^{\circ}C$(soil water content 5%), $47.5{\sim}49.3^{\circ}C$(10%), $48.6{\sim}52.8^{\circ}C$(15%) in 6-hours high-temperature treatment. The higher the soil water content, the stronger the heat resistance property of Sedum. there is. The higher the treatment temperature, the lower the chlorophyll content, and the less the soil water content, the faster the chlorophyll decomposition. The order of hot-temperature resistance was S. reflexum>S. takevimense>S. middendorffianum>S. album>S. sieboldii>S. spurium when soil water content was 5%. The order of hot-temperature resistance was S. album>S. reflexum>S. spurium>S. takevimense>S. middendorffianum>S. sieboldii when soil water content was 15%. The more of soil water content, S. album, S. reflexum, S. spurium had stronger tolerant of hot temperature. These results were consistent with those from the regrowth test and the heat tolerance tested by electrolyte leakage evaluation.

• Ecology and Resilient Infrastructure
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• v.9 no.2
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• pp.107-112
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• 2022

This study was conducted to investigate the effects of mulching materials in extensive green roof system by comparing and analyzing the soil moisture content and growth response of Lychnis cognata according to the types of organic mulching materials. The experimental group consisted of a control group that did not use mulching material (Cont.) and a total of five treatment groups, including cocochip (C.O), woodchip (W.O), straw (S.T), and sawdust (S.A), depending on the mulching material. The soil moisture content according to the type of organic mulching material was high in the order of W.O > S.T > Cont. > C.O > S.A, and there was a significant difference especially in S.A. The plant height showed good growth in the order of S.T > Cont. > C.O > W.O > S.A, and there was no significant difference by mulching materials in other growth items except for plant height. Both the chlorophyll and plant water contents were superior to those of untreated group, so the treatment of organic mulching materials is considered to be effective in maintaining the chlorophyll and plant water contents of Lychnis cognata. In particular, the soil moisture content was affected by the characteristics of the mulching material itself. Based on these results, it is required to use a mulching material suitable for the characteristics of each plant in extensive green roof system and it is considered that this can be overcome through organic mulching when selecting a plant species that is weak to water stress.

• Journal of the Korean Institute of Landscape Architecture
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• v.42 no.6
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• pp.50-59
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• 2014

This experiment was performed in order to study the relationship between physical properties of soil and the growth characteristics of Sedum reflexum. A correlation analysis and multiple regression analysis were performed using SPSS Ver 19.0 for Windows. The multiple regression analysis results of soil physical properties and growth characteristics were as follows. The regression equation: The length=$.993-14.070^*$(soil bulk density)+$.233^*$(solid phase)+$.038^*$(liquid phase)+$.068^*$(permeability). The significance of soil bulk density and solid phase was great. The width=$2.931-33.925^*$(soil bulk density)+$.566^*$(solid phase)+$.206^*$(liquid phase)+$.027^*$(permeability). The significance of soil bulk density and solid phase was great. The wet weight and dry weight of the upper and lower and soil physical properties did not have a direct relationship.

• Korean Journal of Organic Agriculture
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• v.24 no.4
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• pp.787-795
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• 2016

The purpose of this study was to assess drought tolerance of groundcover plants for extensive green roof. Form July to November 2013, plant height, chlorophyll content, soil moisture, evapotranspiration and survival rate was measured. As results, after unirrigation started, Aster koraiensis reached 0% of soil moisture earliest followed by Sedum kamtschaticum, Hemerocallis fulva, Hylotelephium spectabile, Iris sanguinea, Hosta longipes and control. Among the plants, A. koraiensis withered earliest on 19th day of unirrigation experiment, followed by H. longipes and H. fulva (27th day); and I. sanguinea (29th day). S. kamtschaticum and H. spectabile survived even after 120th day of the experiment. As for chlorophyll content, I. sanguinea showed constant values in early stage than rapidly decreased right before its withering. Chlorophyll content of A. koraiensis and H. fulva showed rapid decrease from the beginning, while that of H. spectabile and S. kamtschaticum showed continuous reduction for first 30 days and the reduction was slowed down since then. In conclusion, H. longipes, I. sanguinea and H. fulva were found most applicable for extensive green roof considering scenic aspect.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.1
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• pp.83-97
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• 2013

This study was carried out to suggest an experimental base in selecting the drought resistance of plants. Adopting the natural drought method, this paper studies the drought resistance of 12 kinds of ground cover plants. focusing on analyzing the changes of relative water content on leaf, relative electric conductivity and chlorophyll content in 12 kinds of plants, and and the relation between soil water content under drought stress. The drought resistance of the plants were subject to laboratory and rooftop drought resistance treatments. The Logistic model of nonlinear regression analysis was used to evaluate the lethal time that were predicted with the range of 10.4~30.1d on roof top, and 19.5~39.0d on hothouse. The result shows that with the increase of stress time, relative water content and chlorophyll content on leaf were in a downward trend; the relative electric conductivity was upward tendency. Among 12 species of ground cover plants, exclude Pulsatilla koreana, Ainsliaea acerifolia were selected for rooftop plants because they showed resist drought strongly and took adaptive ability.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.19 no.2
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• pp.55-69
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• 2016

Significant efforts are being devoted in mitigating the urban heat island effect, and extensive green roofs are an option for mitigation. The purpose of this study was to compare the surface temperature, vegetation types, and plant species on an extensive green roof. Test beds were created in May 2015, and the surface temperature was monitored from June to August. The test beds comprised polyculture and monoculture. Polyculture was divided into three types, and monoculture comprised eight plant species. An extensive green roof is effective in reducing temperature by forming a shade and preventing sunlight from falling on the surface of buildings, which mitigates the urban heat island effect. Consequently, the surface temperature of the green roof and that of concrete during summer reduced from $17.8^{\circ}C$ to $7.3^{\circ}C$. The temperature reduction was greater on using polyculture than on using monoculture, but monocultures of Sedum takesimense, Hemerocallis dumortieri, Allium senescens, Aster yomena, Belamcanda chinensis, and Aster koraiensis also produced good results. The temperature reduction effects of Polygonatum odoratum var. pluriflorum f. variegatum, Phlox subulata, and Thymus quinquecostatus var. japonica were excellent compared with those of concrete but were less than those of other plant species. Careful attention is needed for the management of extensive green roofs. Studies on the plant species and types of extensive green roof should continue to mitigate the urban heat island effect.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.18 no.1
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• pp.115-125
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• 2015

This study was carried out to analyze comparison of carbon storage and physicochemical properties of vegetation soil for extensive green rooftop established at Seoul National University in september 2013. For this study, 42 plots were made by 2 kinds of vegetation soil including A-type and B-type. A-type vegetation soil plots were made of 90% perlite and 10% humus and B-type vegetation soil plots were made of 60% perlite, 20% vermiculite, 10% coco peat and 10% humus. This study used 6 kinds of plants which are Aster koraiensis, Sedum takesimense, Zoysia japonica Steud, Euonymus japonica, Rhododendron indicum SWEET and Ligustrum obtusifolium. Field research was carried out in 11 months after planting. Physiochemical properties of B-type vegetation soil plots were better than A-type vegetation soil plots in every way and soil carbon content was also higher at B-type vegetation soil plots as well. B-type vegetation soil plots were maintained 10 to 20% higher soil water content than A-type vegetation soil plots of the study period. The species of herb which showed the best carbon storage was Zoysia japonica Steud at B-type vegetation soil plots. The species of shrub which showed the best carbon storage was Ligustrum obtusifolium at B-type vegetation soil plots. Plants generally showed better growth at B-type vegetation soil plots and B-type vegetation soil plots were higher than A-type vegetation soil plots in soil carbon stock.