Study On Water Characteristics Of Five Common Urban Forest Species

Water resources,as the basic material for the existence of living organisms on the earth,play an extremely important role in the development and continuation of life.It is because of the existence of water that the earth has green plants and life,and Water is an important condition and basis for the growth and construction of plants.Urban forests are an important part of urban ecosystems and have important ecological service functions,while tree species in urban forests playing an important role.During urban arid and dry areas or periods,making full use of limited water resources,selecting suitable tree species,solving the survival and growth of trees,improving the survival rate and preservation rate of trees,and improving the ecological environment,which are problems that need to be urgently resolved.The experiment was conducted at the Donghu Campus of Zhejiang Agriculture and Forestry University.The test materials were common urban forest species Elaeocarpus glabripetalus,Cinnamomum camphora,Sapindus mukorossi,Choerospondias axillaris and Cunninghamia lanceolata.Using P-V technology,leaf water potential measurement technology,leaf photosynthetic measurement technology,and relative water content determination technology,five tree species were continuously monitored in the three seasons(spring,summer,and autumn),and ten water characteristics of five tree species in different seasons were obtained.Indicators include: leaf water potential,transpiration rate,stomatal conductance,water use efficiency,osmotic potential at incipient plasmolysis,maximum osmotic potential at saturated water content,cell wall elastic modulus,the ratio of bound water to free water,relative water content at incipient plasmolysis.Finally,using Fuzzy function method to comprehensively evaluate drought resistance of five tree species,the results are as follows:(1)It shows that the order of drought tolerance of the five tree species is not exactly the same.by comparing 10 different water indexes.Leaf water potential is currently a good indicator of plant drought resistance.According to the leaf water potential mean values of five tree species in the three seasons(spring,summer and autumn),the drought resistance of the five tree species was ranked as follows: Choerospondias axillaris > Cunninghamia lanceolata > Cinnamomum camphora > Elaeocarpus glabripetalus > Sapindus mukorossi.It was initially determined that the drought resistance of Choerospondias axillaris and Cunninghamia lanceolata was relatively strong,while the drought resistance of Elaeocarpus glabripetalus and Sapindus mukorossi was relatively weak.(2)The ten indicators of the five tree species are not exactly the same in size and trend in the three different seasons(spring,summer and autumn).It can be seen that the forest tree species in each city in different seasons are adapting to the external water and changes in other environmental factors with various adjustment methods.(3)The comprehensive analysis results of drought resistance of tree species showed that the drought tolerance of five tree species was different in different seasons(spring,summer and autumn).In spring,the results of comprehensive evaluation are more similar to the results of Tr and Gs,indicating that the ability of the five tree species to adjust themselves to the outside world plays a more crucial role in their drought resistance;In summer,the comprehensive evaluation results are similar to the assessment results of the ? indicator of plant,indicating that cell walls of the five trees are harder in the summer and have a greater role in their drought evaluation;In autumn,the results of comprehensive evaluation are more similar to the results of leaf water potential,indicating that the water potential of the five tree species play a more critical role in their drought resistance in autumn.(4)Through the correlation analysis of five tree species,it was found that the correlation between different water indexes of each tree species was not completely the same,and it can be seen that the various water indexes among different tree species have different mechanisms in the process of drought resistance.