沙埋对樟子松(Pinus sylvestnis var.mongolica)幼树生长特性的影响

Effects of Sand Burial on Growth Properties of Pinus sylvestnis var.mongolica

沙埋对沙漠植物存活和生长影响的研究文献已有很多,但有关沙埋对樟子松(Pinus sylvestnis var.mongolica)幼树存活及生长适应的研究报道还很少。樟子松是中国北方沙区迄今为止推广种植范围最广的常绿乔木树种,为了解沙埋对其幼树生长特性的影响,2013年在内蒙古科尔沁沙地研究了不同沙埋深度下其3龄幼树的存活率、株高、顶芽长度、冠幅等生长特性,得到以下结果:樟子松3龄幼树只能耐受其株高以上2cm及其以下的沙埋,沙埋深度为其株高以上2cm时存活率开始下降,超过株高2cm后幼树全部死亡;低于株高以上2cm的沙埋能够促进樟子松幼树的高生长和茎粗生长,其中以沙埋深度为株高25%和50%时的增长幅度最大;同样,低于株高以上2cm的沙埋也有利于樟子松幼树顶芽生长,但以75%和100%沙埋顶芽生长幅度最大;沙埋可导致樟子松幼树冠幅的下降,但与不沙埋对照的差异不显著;少量沙埋对于樟子松幼树生长的促进作用主要源于沙埋能够导致根系层土壤温度的降低和水分增加,而完全沙埋致使光合面积减少,被埋叶片无法呼吸进而腐烂是樟子松幼树死亡的主要原因。

There is a great deal of literatures on the effects of sand burial upon the survival and growth of desert plants,but the effects of sand burial on survival of Pinus sylvestnis var.mongolicasaplings and its growth adaption to sand burial have as yet rarely been studied.P.sylvestnis var.mongolicais an evergreen species planted most widely in the desert areas of northern China.In order to understand effects of sand burial on growth properties of P.sylvestnis var.mongolicasaplings,changes of survival rate,plant height,stem diameter,terminal bud length,canopy areas of P.sylvestnis var.mongolicasaplings in different sand burial depths were studies during 2013 in the Horqin Sandy Land of Inner Mongolia.The results showed that the maximum tolerance of the saplings to sand burial is 2 cm depth above plant height,the survival rates of saplings began falling when the burial depth was 2 cm above the plant height,and the all saplings died after the burial depth exceeded 2 cm above the plant height.Sand burial below2 cm above the plant height could promote height growth and stem diameter growth of the saplings,in which the increased magnitudes were largest in the burial depth being 1/4 and 1/2 plant height.Similarly,sand burial below2 cm above the plant height also could promote terminal bud growth of the saplings,but the increased magnitudes were largest in the burial depth being 3/4 and 4/4 plant height.Sand burial could result in a decrease of the plant canopy,but the differences were not significantly among the canopies at the burial treatments and no burial treatment.Promoting effect of the partial burial to the sapling growth may be attributed to decrease of soil temperature and a increase of soil moisture in the root layer resulted from sand burial,the main reason of complete burial to result in death of the sapling could attributed to a decrease of photosynthetic area and rot of leaf without breathe after sand burial.