Study On Crown Structure Model Of Fast-Growing Eucalyptus Clones

Plantation is the important component of forest ecological system,the decline in global forest resources led to the rapid development of the plantation,the effective development of artificial forest is also an important way to achieve sustainable forest management.In Eucalypt plantation,crown layer can intercept sunlight,rainfall and decide canopy density,thus affects forest productivity and utility rate of space,for the low quality and low benefit Eucalypt stand,this is an important means of forest form improvement to change the forest canopy structureis.The study chose Eucalyptus cloned DH32-29 ranging from 1 to 5 years old at random,that tree has the advantages of fast growth rate,the straightening trunk,short rotation,wide planting range and so on,and picked out 30 trees whose growth factors and all living branch attributes data were measured.Through the level of Eucalyptus branches attribute factor,the crown profile,crown volume and crown surface area data,regression analysis with forest factors,chosen the optimal model to simulate canopy space structure,offering a theoretical base for technique of pruning lift and Eucalypt plantations for clear wood.The main results are summarized as follows:1、To construct and analyze Eucalypt model of primary branch attribute factor,the multiple linear regression method is more effective in the construction of Eucalypt primary branch number relevant model and the mean branch diameter model.The composite model fitting method is more effective in primary branch chord length model,the mean branch length model and the mean chord length model;The regularity between branch angle,the distance into canopy and tree-age are not strong.In addition to the mean branch angle reduces with the increase of canopy height regularly in 1 year old,and the mean branch angle model can use multiple linear regression equation;Eucalyptus cloned DH32-29 plantations for clear wood production can either be pruned for the first time between one and two years or in the second year after afforestation.How much to pruning the Eucalyptus cloned DH32-29 is based on the vertical spatial distribution of branch number from different stand age groups,which injects a fresh thought into the study of pruning lift and Eucalypt plantations for clear wood.2、 To construct and analyze Eucalypt model of crown profile,by using 2 kinds of method for fitting the crown depth of crown max-radius and found that effect of the composite model obtained by the exponential function fitting method is best,it can describe different Eucalyptus between individuals at maximum radius of canopy depth better.The composite model can also be used to fit the average mean crown profile model and maximun crown profile model.3、 To construct and analyze Eucalypt model of crown volume and crown surface area,with the Eucalypt growth of tree-age,crown volume and crown surface area show a trend of decrease first and then increase,especially in the 3 and 4 years-old,The value of crown volume and crown surface area show a significant increase are changed greatly.Using effective method of nolinear regression to measure Eucalypt crown profile,crown volume and crown surface area,crown width can significantly influence Eucalypt crown volume and crown surface area,that are significantly positive correlation between them.