The Variation Characteristics Of Heartwood And Sapwood Of Artificial Larix Gmelinii

In this study, ten sample plots of dahurian larch (Larix gmelinii Rupr.) plantations were selected from Lilin farm in Wuying Forest Bureau in Heilongjiang province. Three trees with dominant trees average tree and suppressed trees were selected. Wood discs were cut at intervals of lm along the stem of felled tree. Diameter outside and inside bark, overall ring number, heartwood ring number, heartwood width, sapwood ring number, sapwood width were measured at two directions of northeast and southwest. Variations in heartwood and sapwood among two orientations, trees and stands, from base to the top of the tree, and growth correlation with cambial age, cambial radius, stem cross section diameter and other individual tree variables were investigated using normal distribution test,t test, nonparametric test, variance analysis, multiple comparison, and correlation and regression analysis methods.The results showed that tree height、DBH、crown width、HLB、tree age have impacts on the growth of heartwood and sapwood, while the influence of individual tree variables was different.Ring number of heartwood and sapwood increased with cambial age increased.The heartwood ring number was significantly positively correlated to cambial age(P<0.0001).Cambial age could account for over 90% of the variation of heartwood ring number, however,only 46% of the variation of sapwood ring number.The heartwood and sapwood radius were strongly positively correlated to the cambial radius. However, the correlation between the sapwood width and cambial radius was significantly lower than the heartwood radius.Heartwood radius, heartwood area, sapwood width, and sapwood area have significant correlation with cambial age and outside and inside bark diameter (P<0.0001).The cambial age had a more significant effect on heartwood than on sapwood, and stem cross-section diameter had a more significant effect on sapwood area than on sapwood width. The variations of heartwood and sapwood’s growth were well explained by outside and inside bark diameter..However, sapwood width is bigger at stem base, remained relatively constant above lm to stem, and then decreased at top of the tree. There are no significant variations among two orientations (P>0.05); there are significant variations among trees and stands (P<0.05) and diameter at breast better explained the variations of heartwood and sapwood among trees.