The Studies On Carbon-fixing,Oxygen-releasing,Temperature-reducin G And Humidity-increasing Of Community Based On LAI

With the rapid development of urbanization, ecological benefits of urban green community more and more attention. How accurate and objective evaluation and an-alysis of urban ecological benefits, is important basis about the measure of the qualit-y of the urban environment and determination of urban development planning and other so.This is the main way to estimate ecological function of the community or a large area of green -based LAI.In this paper, we chose 20 artificial communities (each community is divided into tree layer, shrub layer, chip plant shrub layer, independent shrub layer o, without herb layer) in Wuhan 20 as the research objects, to study the diurnal changes of environme-ntal and photosynthetic about the garden plants of communities in the summer (July and August), then to establish the regression models between the community carbon fixation and oxygen, cooling and humidification function and environmental factors, final to calculate the amout of community carbon fixation and oxygen and cooling and humidification the level of functional value,so the main research results are as follows:(1)The diurnal variation of the temperature, humidity and light intensity is basically the same from small stations WATCHDOG and LI-6400 photosynthesis system, the temperature correction model from WATCHDOG and LI-6400 photosynthesis system, y= 18.75x-0.5x2+0.005 x3-204.16 (R= 0.75038), as well as small weather station measuring temperature x and y photosynthetic systems measure;the humidity correc-tion model is y= 26.82+0.52 x, (R= 0.6353), as well as small weather station meas-uring temperature x and y photosynthetic systems measure;the light intensity correc-tion model is y= 22.70425X0.60745, (R= 0.7663), as well as small weather station measuring temperature x and y photosynthetic systems measure.(2)The maximum net photosynthetic rate of arbor (Amax) order of Prunus cerasifera f. atropurpurea> Magnolia grandiflora> Cerasus serrulata London var.lannesiana Ma-kino> Cinnamomum camphora (L.) Presl.> Koelreuteria paniculata>Ligustrum luci-dum Ait.> Osmanthus fragrans> Ginkgo biloba. The maximum net photosynthetic rate of shrub (Amax) order of Lagerstroemia indica> Photinia serrulata>Pittosporum tobira> Ligustrum x vicaryi Hort.> Loropetalum chinense var. rubrum> Rhododend-ron simsii Planch.> Chimonanthus praecox> Mahonia fortunei (Lindl.) Fedde..The light utilization of arbors is greater than the potential of shrubs, but the ability to take advantage of low light of shrubs better than arbors, arbors is good at glare.(3) In species level, the regression model whose prediction accuracy is greater than 80% between net photosynthetic rate, transpiration rate and temperature, humidity, light intensity of the net photosynthetic rate, transpiration rate and temperature:Tree layer, Y1=0.016x1-7.658E-6x12-0.035, R2=0.585,, as the prediction accuracy of 86.62%; chip plant shrub layer, Y1=0.009x1-4.214E-6x12+0.611, R2=0.382, as the prediction accuracy of 80.39%; shrub layer Y1=0.002x1+0.448x3+1.128x2-65.175, R2=0.534, as the prediction accuracy of 80.87%; tree layer Y2=0.264x10.363, R2=0.506, as the prediction accuracy of 89.53%; chip plant shrub layer, Y2=0.064x10.53, R2=0.544, as the prediction accuracy of 80.95%; shrub layer Y2=0.136x10.44, R2=0.433, as the prediction accuracy of 82.62%. Note:Y1 is photosynthetic rate (μmolCO2.m-2s-1), x1 is photosynthetically active radiation (μmol.m-2s-1), Y2 is transpiration rate (μmolH2O.m-2s-1), x2 is temperature(℃)(4)In community level, the regression model whose prediction accuracy is greater than 80% between net photosynthetic rate, transpiration rate and temperature, humidity, light intensity of the net photosynthetic rate, transpiration rate and temperature:Tree layer, Y1=0.016x1-7.658E-6x12-0.035, R2=0.585, as the prediction accuracy of 86.62%; chip plant shrub layer, Y1=0.009x1-4.214E-6x12+0.611, R2=0.382, as the prediction accuracy of 80.39%; shrub layer, Y1=0.002x1+0.448x3+1.128x2-65.175, R2=0.534, as the prediction accuracy of 80.87%;tree layer, Y2=0.264x10.363, R2=0.506, as the prediction accuracy of 89.53%; sheet plant shrub layer, Y2=0.064x10.53, R2=0.544,as the prediction accuracy of 80.95%; shrub layer, Y2=0.136x10.44, R2=0.433, as the prediction accuracy of 82.62%. Note:Y1 is photosynthetic rate (μmolCO2.m-2s-1), x1 is photosynthetically active radiation (μmol.m-2s-1), Y2 is transpiration rate (μmolH2O.m-2s-1), x2 is temperature (℃)(5) In community the highest of LAI is up to 15.012, lowest is 6.084, the sequence of LAI is 5<11<6<9<15<13<17<19<3<12<20<16<2<7<8<14<4<10<1<18. The carbon sequestration and oxygen release date, the amount of cooling and humid-ification day community of per unit leaf area as a whole order of 18<11<6<13<8 <19<15<9<4<5<1<20<17<3<12<14<16<7<10<2. In community between the size of leaf area index and carbon fixation and oxygen, the amount of cooling, humidification function on unit leaf area is not consistent, then communities richer level of carbon fixation and oxygen and cooling and humidification is better.(6) The highest value of the community carbon fixation and oxygen release date and day cooling and humidification on unit land area (per hectare) based on Leaf Area Index is community 18, daily carbon sequestration capacity of 203.127×104g.hm-2d-1 oxygen release date is 147.733×104 g.hmd-2d-1, cooling of 5.194 ℃, increase the humidity of 72.058%; community order of 11<6<5<13<15<12<19<9<4<1<16 <17<20<8<7<14<3<10<2<18.