Physiological Response Of Urban Greening Trees To Dust Pollution-a Case Study Of Aksu City

Urban greening trees play an important role in reducing air pollutant in atmospherethrough their leaves. In this study, the main greening tree species in Aksu City werechosen as the research object, dust amount of unit leaves area and relativephotosynthetic parameters were examined to explore the relationship between dust onthe leaves and physiological reacts of trees. Tree leaves can absorb the dust in theatmosphere, at the same time badly affected by the dust on the leaves. This paperincludes the various tree species: Populus alba var. pyramidalis, Salix babylonica,Ulmus densa, Fraxinus rhynchophylla etc and5different functional areas: West lakeindustrial park, Cement factory, Television station, Dolan park, K kyar forestadministration station. The aim of the study is that comparing dust retention capacity ofdifferent tree species in Aksu City, examine photosynthetic parameters of trees, analyzethe relationship between different parameters, therefore conclude how the trees absorbdust, how the dust affect trees physiological functions, at last, the most tolerable oracceptable tree species can be chosen though our study results.The results of this study showed that:(1) The diurnal variation of photosynthetic rate of different tree species in4functional areas has the same bimodal character. Net photosynthetic rate in everyfunctional area got the peak level at11:00and5:00local time, reduced significantlyabout12:00, showing obvious "lunch break" phenomenon. Dust amount of the leaves ordust pollution level of the environment in the other word is closely related with thephotosynthetic rate. The average photosynthetic rates of trees in West lake industrialpark were lower than other places.(2) The diurnal variation of stomata conductance in different functional areas waskeep balance with the variation of photosynthetic rate. That means the two parameterhad the same changing trend. Under the combined effects of environmental factors, treespecies decreased stomata conductance, at local time13:00, this change with diurnalvariation consistent description of stomata conductance is the major internal factorsaffecting photosynthetic rate. Under the joint action of stomata conductance andphotosynthesis rate, tree species in different functional areas of intercellular CO2concentration was relatively consistent with diurnal variation, got the peaking at11:00am, the lowest at15:00.(3) Analysis of tree transpiration rate changes showed that each speciestranspiration rate trends consistent with the diurnal variation of transpiration ratefluctuations changes. There are two types: single peak, double peaks, in addition to treesin Dolan Park Fraxinus rhynchophylla, Populus alba var. pyramidalis, Ulmus densatranspiration rate changes had one peak. In television Juglans regia, Ulmus densaoutside, Fraxinus rhynchophylla, Platanus orientalis, Morus alba transpiration ratechanges had single peak. In Cement factory, Populus alba var. pyramidalis, Platanusorientalis transpiration rate changes had single peak. Single peal curve belongs to thenon-transpiration lunch type. Transpiration rate changes bimodal curve is of thetranspiration rate lunch type. (4) The exchange parameters and results of different functional areas consistentcorrelation between physiological and ecological factors affecting net photosyntheticrate. Foliar water vapor pressure deficit and temperature of the main causes of roadfactor is related to the temperature and air dried.(5) Different tree species in different functional areas fluctuate not much with thetime. At the first cycle, the dust amount is the highest. Weekly average dust amout ordersize of different functional areas can be divided into two categories. Populus alba var.pyramidalis, Platanus orientalis, Ulmus densa in the first class round-week averageorder size of dust-different functional areas are: West Industrial Park> Cement factory> Television station> Dolan Park>K kyar forest administration station Of Fraxinusrhynchophylla, Salix babylonica in the dust-week average size of different functionalareas of the second class order: West industrial park> Cement factory> Televisionstation> K kyar forest administration Station> Dolan Park. Dust amount of severalspecies there are significant differences, the biggest difference of up to seven timesmore. Within two weeks of each species week dust volume presents the first week oflarger than the second week of the trend. In the determination of five tree species in aspecies common features between different locations, with increments of time, dust-are increasing. Species week average dust order: Platanus orientalis>Populus alba var.pyramidalis>Salix babylonica>Ulmus densa> Fraxinus rhynchophylla, dust-weekaverage were:7.85,6.22,6.15,5.81,4.21gm-2.