The Study On The Growth Process And Wood Quality Of The Stump Grafting Populus Tomentosa

The stump grafting populus tomentosa could use powerful nutrition in perennial root,fully absorb the deeper soil moisture, nutrient, cultivating budding tree fast growth, whichshortened the fast-growing update time. The present study focused on the technologicalprinciple, the tree species selection and the superiority, however there was no researchabout wood quality after grafting. With the sprouting reproduction populus tomentosa ascontrol, the stump grafting populus tomentosa was selected as the material in Yixiancounty test in Hebei province. The research fields covered the growth process variationpatterns, wood anatomical characteristics variations and wood basic physical andmechanical properties variations. The results are as follows:(1) The growth process variation patternThe stump grafting populus tomentosa DBH growth, tree height growth and volumegrowth were significantly higher than that of sprouting reproduction trees. The growthpattern were same, and the growth first increased rapidly, and then increased slowly tendedto be stable and at last the growth rate reduced. The fast-growing period of diameter atbreast height was between the1thand9th. The current annual increment of stump graftingpopulus tomentosa appeared two peaks, and the peak value was the13th, while that ofsprouting reproduction populus tomentosa was only one peak and the peak value was at the8th. The tree height increment grew rapidly between1thand10th. And the tree heightincrement of stump grafting trees was significantly accelerated high growth after threeyears. The current annual increment maximum of different reproduction trees was in the3th.The volume growth had been on an upward trend and the stump grafting trees grewfaster. The volume increment rapidly grew after five years. The current annual incrementmaximum of stump grafting trees was in15thwhile that of sprouting reproduction treeswas in13th.(2)The radial variation pattern of main anatomical features of populus tomentosaThe fiber length and width, vessel length and width, the wall to lumen ration of stumpgrafting trees were greater than those of sprouting reproduction trees, while the ratio offiber length to width and micro fibril angel were smaller. From pith outward, the fiberlength, the fiber width, the ratio of fiber length to fiber width, the vessel length and widthall increased by year, reached maximum at some year and then decreased gradually or leveloff. The fiber wall to fiber lumen ratio, the microfibril angel from pith outward decreased at first and then to fluctuate or remained stable. From pith to park, the tissue proportionvariation was small and basic along a center line fluctuation.(3)The axial variation pattern of main anatomical features of populus tomentosaAt the same tree height, the fiber length, the fiber width, the fiber length to fiber width,the vessel length and width of stump grafting trees were higher than the sproutingreproduction trees. While the fiber wall to lumen ratio, the microfibril angel were smaller.From the trunk base, the fiber length, the fiber length to fiber width ratio, the fiber wall tolumen ratio, the vessel length, the microfibril angel of populus tomentosa were firstincreased and then decreased. The fiber width, the vessel width of trees from the baseupward first decreased and then remained stable or slightly reduced. The wood tissueproportion remained stable or increased or decreased in fluctuation around a center value.(4)The main physical properties of populus tomentosaThe dimensional stability of stump grafting populus tomentosa was better than that ofreproduction trees, but there was no significant difference between the trees. The radialshrinkage was minimum, and then followed by the tangential shrinkage, the volumeshrinkage rate change was the biggest.12%moisture density: the density of stump grafting trees was0.48g/cm3and thedensity of reproduction trees was0.42g/cm3. The density of stump grafting populustomentosa was significantly higher than that of reproduction trees. The basic density: thebasic density of stump grafting trees was0.39g/cm3, and it was significantly higher thanthat of reproduction trees. At the same time, the water absorption of stump grafting treeswood was less than the sprouting reproduction trees.(5) The main mechanical properties of populus tomentosaThe mean value of tensile strength parallel to grain of wood was98.76MPa, and themean value of compression strength parallel to grain of wood was37.89MPa among thestump grafting trees. While among the sprouting reproduction trees, the mean value oftensile strength parallel to grain of wood was96.78MPa, and the mean value ofcompression strength parallel to grain of wood was35.84MPa. The bend strength and themodulus of elasticity in static bending of stump grafting trees wood were62.10MPa and8035.61MPa, while those mechanical properties of sprouting reproduction trees were54.06MPa and7594.13MPa. There was no significant difference between the mechanicalproperties of the two kinds of reproduction populus tomentosa except the bending strength.