Plot B (Sedum plot) received a drought-tolerant succulent plant It is an evergreen perennial herb native to Central American With fairly fast establishment rate, it can form a full cover in one growing season and has been adopted for roof greening in tropical areas Sedum species assumes the Crassulacean acid metabolism (CAM) photosynthetic mode by closing their stomata in daytime under water deficit condition At night time, stomata open to absorb carbon dioxide which is stored in leaf tissues for use in daytime photosynthesis when stomata are closed. Thus the transpiration rate of Sedum could be suppressed on hot days with dry substrate.