| Because of its unique landscape value,Betula platyphylla is extremely favored by garden workers,but the low transplantation survival rate of large-scale Betula platyphylla has been criticized,yet to be resolved.In the past,the study on improving the transplantation survival rate of Betula platyphylla was only at the level of specific transplanting operation technology and improving the regeneration ability of root system through exogenous hormones,but neglected the correlation research from the perspective of tree transplant survival theory(tree balance theory).The aim of this paper is to provide solid technology support to Betula platyphylla transplantation based on the theory of tree planting survival theory-tree balance theory and the research on the distribution of leaf area and the regular spatial distribution of fine roots.In the fall of 2016,as the objects of study,three Betula platyphylla in different canopy margins(3 cm,6 cm,9cm)were planted.The spatial distribution of leaf area was studied by using the method of standard wood analysis,branch analysis and CID-203 hand-held leaf area meter produced by American CID Company.The spatial distribution of fine root was studied by using the whole plant system and WinRHIZO root system analysis system in order to set up the leaf area pruning retention model and the root pruning retention Quantity model.Research indications:(1)The vertical distribution of leaf area:this paper selects five Betula platyphylla section samples according to the length of the canopy,and the total leaf area of each canopy and the total leaf area per crown was calculated to figure out leaf area of Betula platyphylla at different vertical layers decreases with the increase of canopy.(2)The horizontal distribution of leaf area:this paper divides Betula platyphylla into 5 pieces evenly and numbered as branch section ??branch section ??branch section??branch section??branch section ?.The horizontal distribution of the leaf area on the primary branches increased first and then decreased from the base of the branches to the tip of the branches,and the highest distribution ratio was at branch section II and the least was at branch section V.(3)Based on the study of the spatial distribution of leaf area,the percentage model of leaf area of the first branch and the horizontal distribution were established to calculate the partial pruning on the first branch,as a result,the percentage of the total leaf area of the whole shoot was the percentage of the total leaf area of the first branch,and the model was as follows:P(primary leaf area)= 0.022lndl/DINC + 0.043,the coefficient of determination R2 =0.844,the model accuracy is 96.113%at the level of confidence a = 0.01;and the percentage of the total leaf area of the first branch is P(1/5 primary leaf area)== 0.548e-2.053(dl-d2),the coefficient of determination R2 = 0.876,The model accuracy is at the level of confidencea ?= 0.01,93.989%.And then deduced the amount of Betula platyphylla leaf area pruning retention model P(leaf area retention)=(?)(4)The vertical distribution of fine root:Betula platyphylla was studied by means of whole plant digging method.The root distribution of Betula platyphylla at different DBHs reached 90cm depth.Measured the surface as the start point,30 cm depths as a level to calculate the distribution.The results showed that the distribution of fine root(root length,root surface area and root tip number)showed a decreasing trend with the soil layer going deep.In addition,the vast majority of the distribution concentrated in 0-30cm soil layer,below 30cm soil layer was evenly distributed.(5)The horizontal distribution of fine root:Through this paper,the root system of Betula platyphylla at different DBHs was fully analyzed by the whole plant mining method,and the horizontal extension radius of Betula platyphylla at different DBHs reached 18d.Calculated the rim of trunk as start point,3 times of DBH as a level.As a result,(Root length,root surface area,root tips number)the horizontal distribution in different soil layers increased and then decreased with the further distance from the trunk.(6)Based on the study of the spatial distribution of the fine root of Betula platyphylla,,the model of fine root spatial distribution was established.Firstly,the root of the root is taken as the dependent variable,the square of the distance from the trunk(x = nd)times vertical depth(h)is taken as independent variable in order to calculate how many root tip equals to(N)=447.383[(nd)2h]0 528,the coefficient of determination R2= 0.966,the model accuracy is at the level of confidence a = 0.01 for 96.582%.Finally,deduced the percentage of the root fine root retention for the partial pruning calculation model as P(root tip number)=447.383[(nd)2h]0.528/447.383[(nmax*d)2hmax]0.528. |
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