A Comparision Study On Water Consume For The Major Landscape Species And Typical Woods In Hefei City

For alleviating the contradiction between city vegetation build and shortage of water resource supply, the plant water consume at leaf scale and individual scale for the major 15 species,as well as at community scale for typical woods was studies on in this paper.The aim for the paper is to provide a theoretic support for water-save woods establishment in city area.The diurnal variation of transpiration and water use efficiencies of the 15 major landscape species in Hefei were measured using Li-6400 in field,and individual plant water dispersal for 7 species of them was calculated,as well as water demand for some typical communities was done.Meanwhile,the regressions for the relationships between transpiration rates,water use efficiency and environmental factors such as temperature,relative humidity, PAR was analyzed.Based on formula built in this paper or cited experiential one for potential transpiration,Individual plant water dispersal and typical plant water demand were obtained.Conclusions are as follows:The diurnal variations of transpiration rate of the major 15 species measured in the paper mostly presented a single peak curve with the high point at noon and the low point at morning and evening,but the double-peak,flag shape or multi-peak curves were found in some cases since the changes in environmental factors as well.Variations in transpiration rate present a narrow peak with steep rise and fall usually,but a wide peak for a few.Mean transpiration rates in four seasons for 15 measured species are in order as follows:Oxalis corymbosa> Hibiscus syriacus> Acer buergerianum> Photinia serrulata> P.cerasifera cv.Atropurpurea> Loropetalum chinense var> Cinnamomum camphora> Osmanthus fragrans> Euonymus japonicus> Photinia davidisoniae> Pittosporum tobira > Pittosporum tobira > Photinia serrulata > Ligustrum lucidum > Magnolia grandiflora > Ophiopogon japonica. Studies on stomatal conduction and transpiration rates of 6 species show that the daily mean conds are as follows in order:Photinia serrulata >P.cerasifera cv.Atropurpurea > Oxalis corymbosa >Punica granatwn >Ligustrum lucidum >Cinnamomum camphora,which is the same as transpiration rate sequence.Three environmental factors affecting transpiration rate are PAR,temperature and relative humidity.All plants respond the same way in the same soil water condition.Water use efficiencies of different species vary obviously in different seasons,and also have different trends,in single peak or multi-peak-like form.Mean water use efficiencies of the 15 species are as follows:Magnolia grandiflora>Hibiscus syriacus > Photinia serrulata > Photinia davidisoniae > Acer buergerianum > Punica granatum > P.cerasifera cv.Atropurpurea > Osmanthus fragrans > Pittosporum tobira > Euonymus japonicus > Cinnamomum camphora > Oxalis corymbosa > Loropetalum chinense var.> Ophiopogon japonica.7 factors affecting plant WUE are:leaf temperature, PAR,CO₂,Ci,Cond,air temperature,and relative humidity.All these factors act together.Individual plant water dispersal for 7 tree species showed a different trend in different seasons.The mean values are as follows:Acer buergerianum> Cinnamomum camphora > P.cerasifera cv. Atropurpurea > Ligustrum lucidum> Punica granatum > Magnolia grandiflora > Photinia davidisoniae; 15 species studied in the paper are divided into four categories according to their water dispersals:Acer buergerianum,Hibiscus syriacus and Osmanthus fragrans belonging to high Tr and high WUE type, Cinnamomum camphora,P.cerasifera cv.Atropurpurea,Punica granatum and Loropetalum chinense var.belonging to high Tr but low WUE type;Magnolia grandiflora,Photinia davidisoniae,Phothnia serrulata and Pittosporum tobira belonging to low Tr but high WUE type;Ligustrum lucidum and Euonymus japonicus belonging to low Tr and low WUE type.Four experiential formulas applied in forest potential transpiration calculation were employed in the paper to estimate potential water dispersal for several typical green spaces,The results showed that the estimation based on Hamon and Kelle are relatively close.Thus the average value accounted using the two methods to be as the transpiration amount for the studied green spaces.The water demand of typical city green spaces in Hefei area was showed as follows:in the same season,same place and same environment,The community with trees- shrubs-grass structure needs most water,The community with only tree layer takes second place,and shrubs at the lowest;for the same plants in the same place, water disperses most in summer,then in autumn,in winter water disperses at lowest.