Objective In order to solve the problem of understory regeneration of Larix principis-rupprechtii plantation in Saihanba Area of Hebei Province, northern China and realize the near-natural management of plantation, it is necessary to study the effects of artificial promotion measures (hereinafter referred to as “promotion”) on understory regeneration.
Method This study took 31 years old L. principis-rupprechtii plantation in Saihanba Area as the research object, we adopted the split plot design and other methods. The experiments of promotion were carried out from four aspects: stand density, litter treatment, seed source and seed treatment. This paper discusses the response of understory regeneration to different promotion measures.
Result The results showed that the regeneration can appear among the treatments and the regeneration frequency was about 100%. The ground diameter and seedling height of seedlings with different densities at the same period had little difference at the end of growth (P > 0.05), while the ground diameter of seedlings had significant differences in two years (P < 0.05). There was no significant difference in survival rate between different treatments (P >0.05), and the overall survival rate remained in the range of 43.68%−87.87%. However, the regeneration density and germination rate of seeds were significantly different among litter treatments (P < 0.05). The regeneration density of 8 633.33 plant/ha of sulcate cleaning (SC) was the highest under artificial sowing, and seed germination rate of 1.79% was also the highest. In addition, the dynamic of regeneration changed with sowing time. When the seeds were sown naturally, the regeneration dynamics among the treatments were relatively consistent, and the peak of seedling germination was at the end of July. When the seeds were sown artificially in the middle of June, only the seeds in SC treatment germinated in large quantities at the end of July.
Conclusion The artificial interference with litter layer and seeding are effective to promote the regeneration of L. principis-rupprechtii plantations. The promotion measures mainly affect the effects of regeneration by affecting the number of seedlings rather than the seedling quality. The sowing time and seed treatments affect the renewal dynamics of seedlings, and artificial sowing of untreated seeds in mid-June can cause the delay of renewal dynamics in the current years. The best way to promote the regeneration of L. principis-rupprechtii plantations is as follows: the first way is to sulcate clean the litter layer and spread the seeds manually before mid-June, the second way is comprehensively clean the litter layer and spread the seeds in early November of the previous year.
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