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    修枝对尾巨桉生长动态及单板质量的影响

    Effects of pruning on growth dynamic and veneer quality of Eucalyptus urophylla×E. grandis

    • 摘要: 以尾巨桉人工林为研究对象,通过设置未修枝、轻度修枝、中度修枝和重度修枝4种修枝强度,采用裂区设计连续2年度实施人工修枝,研究修枝对尾巨桉生长动态和单板质量等级的影响。结果表明:幼林龄尾巨桉生长量受修枝强度的影响更大;随着林龄的增加,胸径生长将在生物量就近分配原则下受到影响,但修枝对树高生长的影响相对较小,这主要与修枝后林冠的高度以及叶片净光合速率有关;经2011和2012年连续实施2次人工修枝后,4种修枝强度的2013年双月连续单株材积、2013年定期单株材积基本一致;重度修枝能增加单板单位面积活节和降低单板单位面积死节,提高单板质量等级;重度修枝是综合尾巨桉生长量和单板质量等级前提下的定向培育无节材的最适宜修枝强度。

       

      Abstract: Using Eucalyptus urophylla×E. grandis plantation as the research material in this paper, the effects of pruning on the growth dynamic and veneer quality were studied by setting four pruning intensities of CK (no pruning), light pruning (cut 25% of the whole canopy), moderate pruning (cut 33.3% of the whole canopy) and heavy pruning (cut 50% of the whole canopy), and pruning in consecutive 2 years with applying split-plot experiment design. The results showed that the growth of young E. urophylla×E. grandis was most influenced by pruning intensity, especially with the increasing of trees age. The increase of diameter at breast height (DBH) was affected under the principle of nearby allocation of biomass; however the growing on the height of tree was affected quite less than that for DBH. The reason of this phenomenon was mainly related to the height of canopy and net photosynthetic rate after pruning. The tree volumes for both bi-monthly continuous and regular growth in 2013 were nearly the same under four pruning intensities after two consecutive pruning in 2011 and 2012. The veneer quality was improved by the heavy pruning, which was able to increase green knots and decrease dead knots per unit area. The heavy pruning is most appropriate method for directive breeding of clear wood based on the growth and veneer quality of E. urophylla×E. grandis.

       

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