大叶白蜡分枝习性与平茬接干措施的研究

The branching habits and measures of evening stubble & connecting stems to the Fraxinus rhynchophylla

大叶白蜡是北方常用绿化树种,但在幼年期干性较差,影响苗木质量,本试验研究了在不同土壤条件和不同密度条件下大叶白蜡分枝类型及其比例,也研究了在不同苗龄和不同土壤条件下平茬的效果。结果表明:大叶白蜡可以分为4种分枝类型:单轴分枝、合轴分枝、假二叉分枝和三叉分枝。各种分枝比例与土壤条件关系密切而与密度关系不显著,优良的土壤条件能够有效的提高单轴分枝和合轴分枝的比例,在本试验中这两种分枝比例达到70%,从而提高自然接干的比例。对于过早分枝的苗木则应选择较好的立地条件,在定植后的第2年进行平茬接干,在平茬后的当年可达到1.8 m以上的干高标准。

The Fraxinus rhynchophylla is one of the popular forestation species in north China, so the quality of nursery stock was affected as the trunk shape is poor in its young stage. This experiment has done researches on the branching types and the proportion of the Fraxinus rhynchophylla under different soil and density conditions. Meanwhile it has also studied the effects after evening the stubble in different seedling age and under the different soil conditions. The result indicated that the Fraxinus rhynchophylla may be divided into 4 types of branching： the monopodial branching, the bipodial branching, the false bibranching and the tribranching. All branching proportion has close relation with the soil conditions, but has little to do with the density conditions. The good soil conditions can enhance the proportion of monopodial branching and bipodial branching effectively, with a number achieving 70% in this experiment, and increasing the proportion of connecting the stems naturally.For those premature branching nursery stocks, better site condition should be chosen. They should be evened the stubble after the fix planting next year. They might achieve 1.8 m high after the even stubble at the same year.