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    白东雪, 刘强, 董利虎, 李凤日. 长白落叶松人工林有效冠高的确定及其影响因子[J]. 北京林业大学学报, 2019, 41(5): 76-87. DOI: 10.13332/j.1000-1522.20190016
    引用本文: 白东雪, 刘强, 董利虎, 李凤日. 长白落叶松人工林有效冠高的确定及其影响因子[J]. 北京林业大学学报, 2019, 41(5): 76-87. DOI: 10.13332/j.1000-1522.20190016
    Bai Dongxue, Liu Qiang, Dong Lihu, Li Fengri. Determination and analysis of height to effective crown for plantedLarix olgensis trees[J]. Journal of Beijing Forestry University, 2019, 41(5): 76-87. DOI: 10.13332/j.1000-1522.20190016
    Citation: Bai Dongxue, Liu Qiang, Dong Lihu, Li Fengri. Determination and analysis of height to effective crown for plantedLarix olgensis trees[J]. Journal of Beijing Forestry University, 2019, 41(5): 76-87. DOI: 10.13332/j.1000-1522.20190016

    长白落叶松人工林有效冠高的确定及其影响因子

    Determination and analysis of height to effective crown for plantedLarix olgensis trees

    • 摘要:
      目的以黑龙江省长白落叶松人工林为研究对象,分别从光合作用机理角度以及树干断面积生长量与叶生物量垂直分布规律角度提出了有效冠高(HEC)的确定方法,并分析了影响有效冠高的主要因子。
      方法首先,根据3株光合作用测定样木不同轮层枝叶在生长季内光合累积碳量对树干的贡献量判定有效冠位置,并分析该位置与累积叶生物量垂直分布的关系,提出基于累积叶生物量垂直分布判定有效冠位置的标准。其次,采用传统方法,通过分析树干断面积增长量与叶生物量的实际垂直分布规律,判定有效冠高。最后,根据实测的19块标准地133株解析木数据,对比两种方法判定的有效冠高的差异,确定有效冠高的判断依据,并分析有效冠高与林木因子及林分因子的关系。
      结果树冠中各轮层枝叶对树干的净碳贡献量随相对着枝深度(RDINC)的增加表现为“单峰”形式的变化趋势,将净碳贡献量大于0的轮层及以上部分确定为有效冠。3株光合样木有效冠高存在一定差异,分别为2.84、4.73和4.38 m,但有效冠位置对应的相对累积叶生物量分别为87%、90%和86%,均接近于90%,因此,可以采用相对累积叶生物量为90%处的位置作为判定有效冠位置的依据。相较于该方法,采用分析断面积增长量和叶生物量垂直分布规律判定HEC位置的方法虽然存在一定差异,但二者的差异并不显著。林分年龄(Age)是与HEC相关性最高的林分因子,二者呈线性正相关,相关系数达到0.8;单木因子中,接触高(CH)和树高(H)与HEC呈显著的线性正相关关系,相关系数为0.9左右。林分密度(SD)和竞争指数(CI)与HEC呈负相关,但该现象主要是受Age、CH和H的影响。
      结论采用相对叶生物量累积达到总叶生物量90%所对应的位置作为判定有效冠的依据具有一定可行性,处于该位置之上的相邻轮枝的高度即为有效冠高。有效冠长占总冠长的比例平均为四分之三,最小值为二分之一,本研究结果为长白落叶松幼龄林的人工整枝提供了科学依据。

       

      Abstract:
      ObjectiveBased on the data of planted Larix olgensis trees in Heilongjiang Province of northeastern China, the height of effective crown (HEC) was respectively determined from the principle of photosynthate allocation and the vertical distribution of the trunk basal area increment and the leaf mass. The influencing factors of HEC were also analyzed.
      MethodFirst, HEC was determined according to the contribution of carbon from branches in each pseudo-whorl to trunk, based on the data of three photosynthetic sample trees during the growing season. The relationship between HEC and the vertical distribution of cumulative leaf mass was analyzed, and the rule for determining HEC was defined according to the vertical distribution of cumulative leaf mass. Then, HEC was also judged by comprehensive analysis of the vertical distributions of the trunk basal area increment and the leaf weight by adopting traditional method. Finally, according to the data of 133 branch analysis sample trees in 19 standard plots from different stand conditions, the difference of HEC determined by above two methods was compared, and consequently the judgment basis for HEC was determined. The main influencing factors and changing rules of HEC were analyzed.
      ResultThe net carbon contribution of branches in each pseudo-whorl exhibited an " unimodal” curve with the increment of relative depth into crown (RDINC). The effective crown was consisted of the branches having positive contribution to trunk. The HEC of three photosynthetic samples were 2.84 m, 4.73 m and 4.38 m, respectively. But the relative cumulative leaf mass corresponding to HEC was 87%, 90% and 86%, which were close to 90%. Thus, it could be the principle of HEC determination. Comparted to above method, although there were some differences of the HEC determined according to the vertical distributions of the trunk basal area increment and the leaf weight, the differences between the two were not significant. Stand age (Age) showed the strongest correlation with HEC among all stand factors, it was linearly and positively correlated with HEC and the correlation coefficient was up to 0.8. The mean crown contact height of neighboring trees (CH) and tree height (H) exhibited a significant linear and positive correlation with HEC, and their correlations were about 0.9. Stand density (SD) and competition index (CI) were negatively correlated with HEC, but these were mainly diven by Age, CH and H.
      ConclusionIt was feasible to use the height of the adjacent pseudo-whorl above the position that relative cumulative leaf mass was up to 0.9 from treetop to the base of crown as HEC. The mean and minimum values of the ratio of effective crown length to whole crown length were 3/4 and 1/2, respectively. Our results provide a scientific basis for artificial pruning of young Larix olgensis forest.

       

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