林分结构对辽东山区蒙古栎林天然更新的影响

目的 探讨林分结构与林下更新幼苗之间的关系，为人工促进天然更新提供理论依据。 方法 以辽东山区蒙古栎林为研究对象，采用拟合模型和Pearson相关分析法，研究了林分空间结构对蒙古栎天然更新的影响。 结果 （1）林分断面积对更新幼苗密度影响显著，随林分断面积的增加，幼苗密度呈增加趋势，当断面积达到31 m2·hm−2，幼苗密度增加逐渐放缓；（2）林分断面积与幼苗基径和苗高呈显著负相关关系（P < 0.05）；（3）林分竞争指数和密集度均与幼苗密度之间存在典型的抛物线关系，与密集度相比，竞争指数对幼苗密度的影响更显著；（4）林分空间结构对更新幼苗的物种多样性影响显著，林分的混交度越大，垂直结构越复杂，更新幼苗的种类和Shannon-Wiener多样性越高。（5）多元逐步回归分析结果显示：林分断面积、竞争指数和密集度是影响蒙古栎林更新幼苗密度的主要因子。 结论 人工促进蒙古栎林天然更新，改善林下物种多样性，可通过调控林分断面积、竞争指数和密集度的经营方式来实现。

Effects of Stand Structure on Natural Regeneration of Quercus mongolica Forest in Mountainous Area of Eastern Liaoning Province

Objective The relationship between stand structure and undergrowth regeneration seedling was discussed to provide theoretical basis for artificial promotion of natural regeneration. Method Several Q. mongolica forests in mountainous area of eastern Liaoning province were taken as the research objects, the fitting model and Pearson correlation analysis were used, and the effect of stand spatial structure on natural regeneration of Q. mongolica was studied. Result (1) The forest stand base area had a significant effect on seedling density. With the increase of stand base area, the seedling density showed an increasing trend. When the base area reached 31 m2·hm−2, the increase of seedling density gradually slowed down. (2) There was a significant negative correlation between stand base area and seedling base diameter and seedling height (P < 0.05). (3) The relationship between stand competition index and density and seedling density was typical parabola. Compared with density, the effect of competition index on seedling density was more significant. (4) The spatial structure of stand had a significant effect on the species diversity of regenerated seedlings, the higher the degree of mixing, the more complex the vertical structure, and the higher the diversity of regeneration seedling species and Shannon-wiener. (5) Multivariate stepwise regression analysis showed that the main variables influencing the total regeneration density were stand basal area, crowding and competition index. Conclusion Adjusting stand basal area, crowding and competition index are the effective ways to promote the natural regeneration and improve the species diversity of Q. mongolica forest.