The Growth Variation And Prediction Model Of Heart Sapwood And Bark Of Populus Nigra×Populus

Heartwood,sapwood and bark reflect the growth status and wood quality of trees to a certain extent.The analysis of the growth variation of heartwood,sapwood and bark is helpful to deeply understand the growth characteristics of trees.Based on the data of 90 analytical trees from 18 sample plots of Populus nigra×Populus simonii plantation in 6 forest farms in Shangzhi City,Heilongjiang Province in 2020,statistical methods such as analysis of covariance,paired t-test,analysis of variance and multiple comparison were used to study the growth variation of heartwood,sapwood and bark of Populus nigra×Populus simonii.Including azimuth variation,horizontal and vertical variation.The regression models of heartwood annual ring number,heartwood radius,sapwood width and cambium age were established by regression analysis,combined with annual growth and average growth curve,and the prediction models of heartwood radius,sapwood width and bark thickness were established based on mixed effect model.The results demonstrated that:(1)The orientation variation of heartwood,sapwood and bark of Populus nigra×Populus simonii was no significant difference(P>0.05).The heartwood radius and bark thickness decreased with the increase of trunk height,while the sapwood width was larger at the base of the trunk,fluctuated less with height in most areas in the middle of the trunk,and decreased significantly with the increase of height near the top.There was a very significant relationship between heartwood,sapwood and bark growth and trunk peeling radius and DBH(P<0.0001).There were significant differences in the ratio of heartwood and sapwood among different stands,and there were also differences in the ratio of heartwood to sapwood in different stands.(2)The annual ring number of heartwood increased with the increase of cambium age.The earliest formation age of heartwood of Populus nigra×Populus simonii was 2 years,and the growth rate of heartwood and sapwood reached the highest in 12 to 14 years,and tended to slow down after 17 years.In addition,it was found that the continuous annual growth curve and average growth curve of trunk disc radius and heartwood radius all intersect in about 12 years,reaching their respective quantitative mature age,and the growth tends to be flat after 17 years,which was confirmed by the study of growth rate.therefore,it was concluded that the initial growth rate of the tree species is too fast so as to reach the mature age ahead of time.(3)In this study,the prediction model of heartwood radius,sapwood width and bark thickness of Populus nigra × Populus simonii based on mixed effect model has a good prediction effect,which can provide a basis for the prediction of heartwood,sapwood and bark of Populus nigra×Populus simonii in this area.