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    王杰, 陆景星, 王相震, 崔靖亭, 王利东, 刘彦清, 司瑞雪, 贾忠奎. 华北落叶松人工林间伐后9 ~ 10年林下天然更新研究[J]. 北京林业大学学报, 2021, 43(12): 17-28. DOI: 10.12171/j.1000-1522.20200371
    引用本文: 王杰, 陆景星, 王相震, 崔靖亭, 王利东, 刘彦清, 司瑞雪, 贾忠奎. 华北落叶松人工林间伐后9 ~ 10年林下天然更新研究[J]. 北京林业大学学报, 2021, 43(12): 17-28. DOI: 10.12171/j.1000-1522.20200371
    Wang Jie, Lu Jingxing, Wang Xiangzhen, Cui Jingting, Wang Lidong, Liu Yanqing, Si Ruixue, Jia Zhongkui. Natural regeneration of Larix principis-rupprechtii plantations in 9−10 years after thinning[J]. Journal of Beijing Forestry University, 2021, 43(12): 17-28. DOI: 10.12171/j.1000-1522.20200371
    Citation: Wang Jie, Lu Jingxing, Wang Xiangzhen, Cui Jingting, Wang Lidong, Liu Yanqing, Si Ruixue, Jia Zhongkui. Natural regeneration of Larix principis-rupprechtii plantations in 9−10 years after thinning[J]. Journal of Beijing Forestry University, 2021, 43(12): 17-28. DOI: 10.12171/j.1000-1522.20200371

    华北落叶松人工林间伐后9 ~ 10年林下天然更新研究

    Natural regeneration of Larix principis-rupprechtii plantations in 9−10 years after thinning

    • 摘要:
        目的  为进一步完备华北落叶松天然更新障碍的研究体系,本研究从幼苗更新特征方面,揭示或反映华北落叶松林天然更新影响因素。
        方法  于2019—2020年,对不同强度间伐作业(于2010年6月完成)的27年、31年和47年共3个林龄的华北落叶松人工纯林林下幼苗群体展开调查研究。
        结果  (1) 塞罕坝地区华北落叶松林在经过35%极重度间伐、30%重度间伐、20%中度间伐和15%轻度间伐作业以及自然稀疏后的9 ~ 10年里,林下均存在着不同程度的天然更新,更新苗层次均为幼苗,无落叶松幼树存在。幼苗以1年生幼苗为主,多年生幼苗的年龄多为2年。在幼苗更新频率的表现上,更新能力与林龄间呈反比,以27年华北落叶松林的表现最好,47年人工林的最差。(2) 幼苗苗龄分布中,1年生幼苗占比高,更高苗龄的幼苗占比极少,1年生和2年生幼苗的损失较大,在向多年生幼苗的过渡过程中存在更新断层。(3) 幼苗地径和苗高在不同时期以及林分间的差异均较小(P > 0.05)。经过一个生长季,幼苗地径明显减小(P < 0.05),苗高则存在不显著增长(P > 0.05)。(4) 连续2年塞罕坝地区华北落叶松林天然更新等级的观测结果均为更新不良。林龄和林分密度对更新密度的影响较大(P < 0.05),2年内均以31年落叶松林整体更新密度最大(P < 0.05),更新密度则与林分密度间整体呈现正相关(P < 0.05)。相较于2019年,绝大部分样地内更新密度在2020年的表现均存在一定程度地下降(P > 0.05)。(5) 连续2年生长季内幼苗密度的动态变化在3个人工林中相对一致,7月底为萌发高峰期,幼苗损失主要发生在冬季。(6) 生长季成活率和越冬成活率在不同人工林间的差异较小(P > 0.05)。2019年27年落叶松林中生长季成活率要显著优于2020年的(P < 0.05);越冬成活率则在各人工林中均显著低于生长季成活率(P < 0.05)。
        结论  塞罕坝地区3个龄级的华北落叶松人工林,在经过4种强度间伐后的9 ~ 10年里,各人工林下存在不同程度的天然更新。林龄和林分密度主要通过影响林下幼苗的更新频率和更新密度影响到天然更新;而对于林下幼苗的年龄分布、生长状况、更新动态以及成活率等更新特征的影响则较小。即林龄和林分密度主要是通过影响幼苗数量来影响林下更新状态。相对而言,对结实能力更强的幼、中龄林,可通过间伐促进母树生长,提高林分整体的种子产量。并可能通过加大间伐强度和缩短轮伐期等方式,增加间伐对于林分的整体种苗品质、林下更新的环境因子和塞罕坝地区幼苗生长季期限等方面的正向影响。

       

      Abstract:
        Objective  This paper aims to further improve the research system of natural regeneration obstacles of Larix principis-rupprechtii, reveal or reflect the influencing factors of natural regeneration of L. principis-rupprechtii plantations from the aspect of seedling regeneration characteristics.
        Method  From 2019 to 2020, the natural regenerations of the 27, 31and 47 years old L. principis-rupprechtii pure plantations under different intensities of thinning operation in June, 2010 were investigated.
        Result  (1) There were different degrees of natural regeneration under L. principis-rupprechtii plantations in Saihanba area, Hebei Province of northern China after 35% extremely severe thinning, 30% severe thinning, 20% moderate thinning and 15% light thinning and natural thinning for 9−10 years, and the regeneration seedlings were all saplings and there were no larch treelets. The 1-year-old (1a) seedlings were the dominant, and the age of perennial seedlings was mostly 2-year-old (2a). In the performance of seedling regeneration frequency, the regeneration ability was inversely proportional to the stand age. The best performance was 27 years old L. principis-rupprechtii plantations, and the worst was 47 years old plantations. (2) In the distribution of seedling age, 1a seedlings accounted for a higher proportion, higher seedling age accounted for a small proportion, the loss of 1-year-old and 2-year-old seedlings was greater, and there were renewal faults during the transition to perennial seedlings. (3) The differences between seedling ground diameter and seedling height in different stages and stands were small (P > 0.05). After a growing season, the ground diameter of seedlings decreased significantly (P < 0.05), while the height of seedlings did not increase significantly (P > 0.05). (4) The observation results of natural regeneration grade of L. principis-rupprechtii plantations in Saihanba area for two consecutive years were poor regeneration. Stand age and stand density had a great influence on regeneration density (P < 0.05), the overall regeneration density of 31 years old L. principis-rupprechtii plantations was the largest in 2 years (P < 0.05), and there was a positive correlation between regeneration density and stand density (P < 0.05). Compared with that in 2019, the regeneration density of most sample plots in 2020 decreased to a certain extent (P > 0.05). (5) During the growing season, the dynamic changes of seedling density in the three plantations were relatively consistent in two consecutive years. The germination peak was at the end of July, and the seedling loss mainly occurred in winter. (6) The difference of survival rate in growing season and overwintering was small among plantations (P > 0.05), and the survival rate in growing season in the 27 years old L. principis-rupprechtii plantations in 2019 was significantly higher than that in 2020 (P < 0.05), while the overwintering survival rate was significantly lower than that in growing season (P < 0.05).
        Conclusion  Natural regeneration of L. principis-rupprechtii plantations of three age classes in Saihanba area occurred in different degrees in 9−10 years after thinning under four intensities. Forest age and stand density mainly affect the natural regeneration by affecting the regeneration frequency and regeneration density of seedlings under the forest, but have little effect on the regeneration characteristics such as age distribution, growth status, regeneration dynamics and survival rate of seedlings under the forest. That is to say, forest age and stand density mainly affect the regeneration state under the forest by affecting the number of seedlings. Relatively speaking, for young and middle-aged forests with stronger seed setting ability, thinning can promote the growth of mother trees, and improve the overall seed yield of the stand. It is possible to increase the thinning intensity and shorten the rotation period to enhance the positive impact of thinning, improve the overall seedling quality, improve the environmental factors under the forest and extend the growing season of seedlings in Saihanba area.

       

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