Affects Of Nitrogen On Root Repiration Of Fraxinus Bungeana, Ginkgo Biloba, Buxus Sinica And Ligustrum Vicaryi Saplings

Dynamic of root respiration,responses of root respiration of young Fraxinus bungeana,Ginkgo biloba,Buxus sinica and Ligustrum vicaryi trees to temperature and soil nitrogen were studied in the paper on basis of fertilizer addition trail.In order to correctly realize the characteristics of root respiration of the 4 species trees and provide theoretical basis for scientific fertilization.And the main results were as follow:1.The root respiration rates were extremely different between different species(P＜0.001).The month diversity affects the root respiration rate of different species noticeably(0.01＜P＜0.05).The highest root respiration rate of different species occurred in September.The minimum root respiration rate in measuring time are found in November.2.The growth respiration rate was obviously diffrenet among the root in different diameters of Fraxinus bungeana(P＜0.01).So did it exist in maintenance respiration rate.Percentage of Rsa of 1-2mm diameter class in total respiratory rate was more than the other diameter classes.The number reached to 81.0%,which was 1.59 times that of the minimum of Rsa in 2-5mm diameter class.The maximum of Rb occured in 2-5mm diameter class,which was approximately 1.90 times as large as the minimum of Rb in 1-2mm diameter class.The maximum of Rv was 82.3%,which occured in 2-5mm diameter class,was about 1.21 times as large as the minimum of Rb in 1-2mm diameter class. The Rv with the amplitude of the root diameter class variation was approximately 21%.3.The mean values of Rsa in Fraxinus bungeana and Ginkgo biloba L.increased with the increasing of root diameter.The mean values of Rb in Fraxinus bungeana decreased with the increasing of root diameter.The results of multiple comparison indicated that the values of Rsa were significantly different from different root diameters at 5%level and significantly different between root diameters of＞5mm and＜1m,＞5mm and 1-2mm,2-5mm and＜1mm at 1%level.The values of Rsa in gingko(Ginkgo biloba L.) were significantly different between root diameters of＞5mm and＜1mm at 1%level,＞5mm and 1-2mm at 5%level.4.The root respiration rate of four kinds of tree species increased with the increasing of soil temperature within normal limits.There exist exponential relation between the root respiration rate and the temperature.The results of significance test showed that there exist exponential relation between root respiration rate and the temperature in three kinds of tree species at 1%level except the Buxus microphylla.However,there were exponential relation between Rsa and the temperature at 5% level,Rv,Rb and temperatures at 1%level in root diameters of＜2mm in Buxus microphylla.5.The allowance of nitrogen affected the root respiration rate significantly at 0.01%level.After treated by 2N,the root respiration rates in different root diameters of four species were higher than any other treatments during the whole evaluating cycle.There were significantly differences between different fertilizer nitrogen levels in Rsa,Rv and Rb of two shrub species going with seasons. Fertilizer nitrogen levels affected the seasondynamics of root respiration rate in each root diameter of Fraxinus bungeana and Ginkgo biloba significantly at 0.01%level.