水曲柳人工林节子愈合与变色特征

Knot Occlusion and Discoloration of Fraxinus mandshurica Plantation

节子的变色现象严重影响木材质量,了解节子变色规律及其影响因素是确定合理修枝的重要依据。以黑龙江省孟家岗林场地区49年生的水曲柳(Fraxinus mandshurica)人工林为研究对象,采用节子剖析技术分析自然整枝条件时水曲柳节子愈合时间与变色长度的变化规律。结果表明:水曲柳节子平均愈合时间约为6.7 a,约91.1%节子的愈合时间为3~11 a。水曲柳节子均出现了变色现象,平均变色长度约为30.93 mm,约92.2%节子的变色长度低于60.00 mm,仅有不足3.0%的节子变色长度超过80.00 mm。位于西南方向的节子愈合时间明显长于东北方向的节子(P<0.05),与东南、西北方向的节子愈合时间无显著差异(P>0.05)。位于树干高度10.0 m以下的节子愈合时间与变色长度均随节子着生高度的增加而逐渐增加(P<0.05)。节子愈合时间与变色长度均随着节子直径、死节半径的增加而增加,当节子直径超过15.00 mm,死节半径超过30.00 mm时,节子变色长度均明显增大。节子愈合时间越长,节子变色长度越大。水曲柳节子具有极易变色的特性,在生产上为了降低水曲柳节子变色长度,建议修枝时侧枝直径最好控制在15.00 mm内。

As the discoloration of knot affects wood quality seriously, understanding the knot discoloration law and its influencing factors become an important basis for determining reasonable pruning. The 49-year-old Fraxinus mandshurica plantation was taken as the research object atthe Mengjiagang Forest Farm in Heilongjiang Province, and we analyzed the occlusion time and discoloration length of knot by knot analysis technique. The average occlusion time of the F. mandshurica knot was about 6.7 a, and about 91.1% of the knots occluded within 3-11 a. All knots had discolored, and the average discoloration length was about 30.93 mm. Discoloration length of about 92.2% of the knots was less than 60.00 mm, and discoloration length of only less than 3.0% of the knots was more than 80.00 mm. The occlusion time of the knot in the southwest was significantly higher than that in the northeast(P<0.05), but had not significant difference with that in the southeast and northwest(P>0.05). The occlusion time and discoloration length of the knot increased significantly with the increase of knot heightwhen knot was located below 10.0 m(P<0.05). The occlusion time and discoloration length of the knot increased with the increase of knot diameter and the radius of dead knot. When the knot diameter and the radius of dead knot exceeded than 15.00 and 30.00 mm, respectively, and the discoloration length of the knot increased significantly. The longer the knot occluded, the greater discoloration length of the knot was. The above results indicated that F. mandshurica knots discolored easily. In order to reduce the discoloration length of knot, we suggested that branch diameter should be controlled within 15.00 mm during pruning.