| Rain garden is one of the key technologies in the construction of“The sponge city”.Plants with strong function including rainfall runoff,purification and accumulation are the bases of rain garden's function.After surveyed the herbs used in low impact development facilities in Shanghai region,a study of screening and application patterns of rain garden applicable to Shanghai region had chosen twenty five species of herbs for the experiment about physiology,quantitative and the pollutants removal analysis.Making use of membership function for the mean of 25species of plants to drought waterlogging resistance,decontamination capability analysis and sequencing.Ultimately selected and designed the typical herbs plant configure patterns for storage type,purification type and comprehensive type rain gardens as a theoretical basis and design strategies to provide the construction of sponge city in Shanghai.The results of this study are as follows:1.Physiological response of 25 herbs under drought stress.Four index,including,soil water content,membrane permeability of leaves,content of free proline and malondialdehyde of leaves were obtained,were used to evaluate the drought resistance.The results showed that four index of 25 herbs were significantly different under drought resistance.It was indicated that 9 herbs?Miscanthus sinensis‘Morning',Liriope spicata,Miscanthus sinensis etc.?were considered as strong drought resistance,while 16 herbs?Dichondra repens,Miscanthus sinensis Andress‘Zebrinus',Iris pseudacorus etc.?as weak drought resistance.Finally,the ability of drought resistance was sorted by membership function value.2.Physiological response of 25 herbs under waterloging.Four index,including,membrane permeability of leaves,content of free proline and malondialdehyde of leaves were obtained,were used to evaluate the wet resistance.The results showed that three index of 25 herbs were significantly different under drought resistance.It was indicated that Hydrocotyle vulgaris,Lythrum salicaria,Ruellia brittoniana had extremely strong resistance to waterlogging.While Festuca glauca as well as Chlorophytum phnom waterlogging tolerance was weak.3.Study on the removal ability of pollutants of 25 herbs.Three test index included TP,TN and CODcr under heavy,medium and light concentrations of 25 spices of herbs were significantly different with eachother.Results showed that the same plant of 3kinds of concentrations of runoff removal capacity exist certain differences,different plants of the same concentration of runoff pollutants removal capacity are also exist large differences.The TP runoff removal ability of Hosta plantaginea,Reineckia carnea,Sedum lineare and other plants of are better.The TN removal ability of Sedum lineare,Dichondra repens,Liriope spicata and other plants are better than the others.Herbs with better removal ability of CODcr are Lythrum salicaria,Hosta plantaginea,Reineckia carnea and other herbs with better performance in CODcrr asorption.4.Patterns designed with herbaceous plants.Using three maths analysis methods included membership function value and clustering analysis as well as principal component to calculate the comprehensive function of 25 species herbs.The comprehensive function included 3 indexes:the drought and waterlogging resistance as well as runoff pollutant removel ability.Which suitable for storage type rain garden herbs are Hydrocotyle vulgaris,Lythrum salicaria,Reineckia carnea and so on.Runoff pollution is more serious in purifying rain garden herbs were chosen with better pollutant removel capacity included Hosta plantaginea,Lythrum salicaria and Sedum lineare.And then herbs suitable for comprehensive type rain Garden comprehensive adaptability are Sedum lineare,Liriope spicata and Reineckia carnea. |
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