树冠结构对主干生长量垂直分配的影响

1985—1986年用定位测量方法研究了Ⅰ-69杨(Populus deltoides Bartr.cv.“Lux”ex.Ⅰ-69/55)树冠结构对主干生长量垂直分配的影响和主干、侧枝生长量分配的关系。结果表明,空旷地与人工林树干生长量分配趋势不同,前者树冠以下主干生长量较大,而后者的大生长量集中在冠部;人工林树干直径增量以地径处最大,向上逐渐变小,从枝下高处又开始增大,直到冠部。冠部树干直径增量一般都大于枝下干部,且呈波动式起伏;断面积与材积增量的分配,以树干基部较大,向上逐渐减小,随着修枝高度的上移,上部材积分配比额增大;侧枝生长影响主干上下生长量的分配,侧枝断面积增加1cm~2,可使分枝部位上下断面积的差值扩大0.7cm~2左右。修枝对调节树干的直径材积生长量分配有显著作用。可以促进树干上部直径材积生长。

EFFECT OF TREE CROWN DISPOSITION ON THE VERTICAL DISTRIBUTION OF ANNUAL INCREMENT IN THE MAIN STEM OF POPLAR

The effect of tree crown disposition on the vertical distribution of annual increment in the main stem of Populus deltoides Bartr. cv. "Lux"ex. 1-69/55 was studied by measurement at fixed position in 1985-1986. The tend of distribution of annual increment inside plantation was different from outside. The increment of main stem under branches of the latter was more than the former. The maximum increment of stem diameter was at bottom, diminished up to branch height, then increased to crown. With increase of pruning height, the volume increment of crown stem became greater than the below stem. Cross-section area of lateral branch increased 1cm~2, the difference between upper and below section areas at the positions of growing branch was about 0.7cm~2. Pruning is important for reguiation of increment in main stem.