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为探讨灌丛对人工油松幼树生长的影响,以黄土高原灌丛边缘、灌丛中和砍伐释放区3种生境中的9年生同龄油松(Pinus tabuliformis)幼树种群为研究对象,分析了人工油松幼树的冠形特征以及当年主干、枝条和针叶的生长状况。结果表明:(1)人工油松幼树的株高在灌丛边缘、灌丛中和砍伐释放区间差异不显著,冠幅、树冠率、着生绿叶年限、基径表现为灌丛边缘>砍伐释放区>灌丛中,而枝下高与其相反。幼树的冠形特征在砍伐释放区与灌丛中差异不显著。(2)高出灌丛的油松幼树当年生长量与灌丛边缘个体差异不显著;当人工油松幼树低于灌丛时,灌丛不利于油松幼树当年主干及枝叶的生长;砍伐释放(人工抚育措施)减小了灌丛对油松幼树生长的不利影响。(3)灌丛中的油松幼树通过对树冠下层枝叶的自然整枝来减少不必要的营养消耗,进而改变植株的冠形特征。(4)当灌丛对人工油松幼树产生遮阴效应时,幼树将大部分干物质用于主干和枝条长度的生长,在枝条水平上增大叶的生物量比例,增大比叶面积,以适应弱光环境。
In order to investigate the effects of shrubs on the growth of young saplings of Pinus tabulaeformis, the population of Pinus tabuliformis saplings of three-year-old Pinus tabuliformis was studied in three habitats at the shrub edge, shrub and deforestation area in the Loess Plateau. The crown-shaped characteristics of artificial pine saplings and the current growth of trunk, branches and needles. The results showed that: (1) The plant height of young tree was not significantly different between shrub edge, shrub and deforestation zone. The crown width, crown rate, green leaf age, Release area> shrubs, while branch height is the opposite. The crown shape of saplings was not significantly different between deforested areas and shrubs. (2) There was no significant difference in the growth of shrubs between the shrubs and shrubs at that time; when the P. tabulaeformis young was lower than the shrubs, the shrubs were not conducive to the growth of trunk and branches ; Deforestation (manual tending) reduced the adverse effect of shrubs on young tree growth. (3) Young pine trees in shrubs reduce the unnecessary nutrient consumption through natural pruning of the lower branches of the canopy, thereby changing the crown shape of the plants. (4) When the shrubs had shading effects on the saplings of P. tabulaeformis, the sapling used most of the dry matter for the growth of trunk and shoot length, increased the proportion of leaf biomass at the shoot level and increased the specific leaf ratio Area, to adapt to the weak light environment.