不同龄级辽东栎幼苗根系形态对幼苗生长的影响

Effects of Root Morphology on Seedling Growth of Quercus liaotungensis in Different Age Classes on Loess Plateau

为了探究混交林内辽东栎实生幼苗高死亡率的原因,以植物根系生长为切入点,探讨实生幼苗根系的变化规律,以期了解根系形态对幼苗生长的影响,对黄土高原子午岭地区油松(Pinustabulaeformis)+辽东栎(Quercus liaotungensis)混交林中3个龄级(1龄、2龄、3龄)辽东栎实生幼苗的形态、生物量、根系长度和表面积等进行研究。结果表明:随龄级的增加,幼苗根冠比、根系长度与表面积呈上升趋势,表明2、3龄幼苗地下部分需要更多的光合产物。幼苗根系形态研究表明,随龄级增加,根系组成变化使幼苗细根细化,这将导致幼苗生物量分配趋向地下。根系细化与细根表面积减小对于根系的稳定性与吸收作用均有影响。相关分析表明,地上生物量与根系形态间存在相关性,但并非线性,表明根系形态与生物量间关系复杂,应用连续测定与控制试验将有利于揭示两者之间深层次的关系。混交林内,幼苗根系形态的变化对其稳定性和幼苗生物量分配均产生影响,但此类影响是复杂的。对于根系变化如何影响幼苗生长及其对资源的竞争能力,还需进一步的研究与探索。

In order to explore the reason for the oak seedling＇s high mortality in the mixed forest,the author used the growth of plant root as the starting point to find the variation of the roots and understand the influence of root morphology to the growth of seedling.The author analyzed the seedling＇s growth and root morphology of 3 age classes（1,2,3-year-old） Quercus liaotungensis in a Pinus tabulaeformis＋Q.liaotungensis mixed forest stand on loess plateau.The results showed that：with increasing age the root-shoot ratio,seedling root surface area and length were increased,which indicated that the underground parts of seedlings needed more photosynthetic products.Root morphology studies had shown that with increasing age,the changes of root composition led to fine roots become thinner,which would cause the belowground biomass allocation increased in the 2,3-year-old seedlings.Thin fine root and surface area decreases would affect the root stability and absorption.Correlation analysis showed that there was a correlation between root morphology and aboveground biomass,but not linear,which indicated that there had a complex relationship between root morphology and the biomass.A further application of the control experiments with continuous measurement would help people to find out a deep relationship between them.The root morphology was changed with the seedling＇s growth,which affected the root stability and biomass allocation immediately.However,such effects were complex.So people needed a further research and exploration to find out how the root changes influence the seedling＇s growth and the ability of resource competition under the high canopy mixed forest.