Research On The Law Of Empty Rot Rate And Root Distribution Characteristics Of Platanus Acerifolia Based On TRU Tree Radar

As a world-famous street tree,Platanus acerifolia has a very high ornamental value and garden value.According to literature records,Platanus acerifolia has been planted in my country as early as the 12th to 15th centuries,but the large-scale introduction began in 1887 and spread from Shanghai to the whole of China during the Republic of China.With a history of more than 100 years of introduction,Platanus acerifolia has grown into a towering tree and even an ancient tree,but at the same time,it is accompanied by hidden dangers to health and stability.Therefore,this study took a total of 100 Platanus acerifolia trees of various ages as samples,and based on the TRU tree radar to explore the law of vacant rot,the causes of vacant rot,and the distribution characteristics of roots under urban pavement.Provide the basis for street tree health diagnosis,reinforcement,tree management and replacement.The main conclusions are as follows:1.The best fitting model between the age and DBH of the Platanus acerifolia is a power function relationship model,and the equation is A=2.329×D^0.798（R²=0.801）.2.With the increase of the diameter class,the empty rot rate of each height section of the Platanus acerifolia increases.The maximum empty corrosion rate is detected.The section is mainly 120cm high.3.On the DBH height section,89%of the Platanus acerifolia samples were grade II with mild air rot.With the increase of age,the average air rot rate and the proportion of moderate air rot samples of each age class increased.In the A∈[70,80)age class Severe empty rot samples appeared for the first time.4.On the DBH height section,the initial void rot ratio,forming void ratio,and void rot rate fluctuated slightly in the range of 6%,14%,and 19%respectively before the tree age of 60 years,and showed a slow increase with age.The rising trend;after the tree age is 60 years old,the proportion of initial empty rot,the proportion of molding cavities,and the empty rot rate begin to increase sharply,reaching the highest of 24%,34%,and 50%,respectively,and the volatility also increases.The proportion of sapwood decay did not show a significant change rule with age.87%of the samples fluctuated within 0.5%.5.The external damage of Platanus acerifolia is mainly characterized by four types of rotten skin,splitting marks,wormhole bulges and tree knots,which are concentrated in the height range of 120-160cm.The four types of damage will further aggravate the hollow rot of the tree body:rotten skin>splitting marks>tree knots>wormhole bulge.The frequency of splitting marks is the highest,and most of the rotten skin is formed by the further decay of the splitting marks.Overall,this type of damage has the greatest impact on aggravating empty rot.6.The distribution characteristics of the root system of the Platanus acerifolia are as follows:in the vertical direction of 0-1m,the root system is mainly distributed in the range of 40-60cm,accounting for 41.7%on average;with the increase of tree age,the number of root systems on the surface layer of 0-40cm increases.[50,60)age class begins to have a greater possibility of root uplift,and this possibility will further increase with age;in the horizontal direction of 0-3m,0-1m,1-2m,2-3m The number increases successively.