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    管惠文, 董希斌. 间伐强度对落叶松次生林冠层结构和林内光环境的影响[J]. 北京林业大学学报, 2018, 40(10): 11-23. DOI: 10.13332/j.1000-1522.20180021
    引用本文: 管惠文, 董希斌. 间伐强度对落叶松次生林冠层结构和林内光环境的影响[J]. 北京林业大学学报, 2018, 40(10): 11-23. DOI: 10.13332/j.1000-1522.20180021
    Guan Huiwen, Dong Xibin. Influence of thinning intensity on canopy structure and light environment inside Larix gmelinii secondary forest[J]. Journal of Beijing Forestry University, 2018, 40(10): 11-23. DOI: 10.13332/j.1000-1522.20180021
    Citation: Guan Huiwen, Dong Xibin. Influence of thinning intensity on canopy structure and light environment inside Larix gmelinii secondary forest[J]. Journal of Beijing Forestry University, 2018, 40(10): 11-23. DOI: 10.13332/j.1000-1522.20180021

    间伐强度对落叶松次生林冠层结构和林内光环境的影响

    Influence of thinning intensity on canopy structure and light environment inside Larix gmelinii secondary forest

    • 摘要:
      目的为改善林分结构和促进林木生长,对大兴安岭落叶松次生林进行不同强度的抚育间伐,研究落叶松冠层结构和光合特性指标的相关关系,进而探讨改善林内光环境特征的最佳间伐强度。
      方法设置间伐强度为9.43%、16.75%、29.00%、40.01%、53.09%、67.25%的实验样地和未进行间伐作业的对照样地。对不同样地落叶松冠层结构参数和光合特征参数指标值间的差异进行描述性统计,运用相关系数法确定不同指标间的相关关系进而剔除有显著正相关的部分指标,同时运用灰色关联法对各个样地的光环境特征进行综合评价。其中冠层结构选取林隙分数、开度、叶面积指数、叶倾角、直接定点因子、间接定点因子、总定点因子、冠上直接辐射、冠上间接辐射、冠上总辐射、冠下直接辐射、冠下间接辐射、冠下总辐射13项指标,光合特征参数选取蒸腾速率、光合速率、CO2参考值、叶片表面P.A.R、叶片温度、胞间CO2浓度、水蒸气气孔导度7项指标。
      结果各样地林隙分数表现为随间伐强度的增加先减少后增加,开度、直接定点因子、总定点因子与之变化趋势相同,各项指标值均在间伐强度为29.00%的样地中最小;叶面积指数在间伐强度为29.00%时达到最大值;不同间伐强度样地的冠上辐射通量无显著差异性;冠下直接辐射通量和冠下总辐射通量随间伐强度的增加先减少后增加。随着间伐强度的增加,落叶松的蒸腾速率、光合速率、水蒸气气孔导度均呈现先增加后减少的趋势,叶片表面P.A.R、叶片温度先增加后趋于稳定,间伐增加了林地内的CO2浓度;胞间CO2浓度随着间伐强度的增加先减小再增加后减小。林隙分数与开度、直接定点因子、总定点因子、冠下直接辐射、冠下总辐射呈显著正相关,与叶面积指数呈显著负相关;蒸腾速率、光合速率、水蒸气气孔导度之间呈显著正相关性。剔除相关性极强的指标后,冠层结构的林隙分数与光合速率呈显著负相关,叶面积指数与光合速率呈显著正相关。运用灰色关联综合评判林地内的光环境特征,关联度表现为间伐强度29.00%(0.823)>40.01%(0.794)>53.09%(0.739)>0%(0.724)>67.25%(0.713)>16.75%(0.701)>9.43%(0.673)。
      结论落叶松冠层结构与光合特征指标间存在相关性,落叶松冠层的透光率对于光合速率有明显的影响。结合二者综合评价不同间伐强度下的林地光环境特征,抚育间伐强度为29.00%、40.01%的落叶松天然次生林林地的林内光环境特征较好,说明29.00%~40.01%的中等强度间伐有利于林内光环境的改善。

       

      Abstract:
      ObjectiveIn order to restore the forest structure and improve the forest growth of Larix gmelinii in Daxing' an Mountains of northeastern China, the different thinning intensities of forest were carried out to find the relationship between canopy structure and the photosynthetic characteristics of the undergrowth vegetation and to optimize the operating effects of secondary forest.
      MethodThe experimental plots with thinning intensities of 9.43%, 16.75%, 29.00%, 40.01%, 53.09%, 67.25%, and the control plot were set. The canopy structure parameters selected were the gap fraction, canopy opening, leaf area index, leaf inclination, direct fixed-point factor, indirect fixed-point factor, total fixed-point factor, direct radiation on the crown, indirect radiation on the crown, total radiation on the crown, direct radiation under the crown, indirect radiation under the crown, total radiation under the canopy(13 indexes). The photosynthetic parameters selected 7 indexes, i.e. transpiration rate, photosynthetic rate, CO2 reference value, leaf surface P.A.R, leaf temperature, intercellular CO2 concentration, stomatal conductance. They were used to describe the differences between different places and the correlation coefficient method was used to determine the correlation between different indexes. At the same time, the gray correlation method was used to evaluate the light environment of each sample.
      ResultThe results showed that: gap fraction, canopy opening, direct fixed-point factor and total fixed-point factor decreased first and then increased by increase of thinning intensity, and the value of the 4th sample with thinning strength of 29% was the smallest. The leaf area index reached the maximum value when the thinning intensity was 29%. There was no significant difference between the radiation direct radiation on the crown and the total radiation on the crown. The direct radiation under the crown and total radiation under the crown also decreased first and then increased by the increase of thinning intensity. With the increase of thinning intensity, transpiration rate, photosynthetic rate and stomatal conductance all appeared first increasing and then decreasing trend, while leaf surface P.A.R, leaf temperature raised afterwards steadily. Thinning increased the concentration of CO2 in woodland and the intercellular CO2 concentration decreased at first, then increased, reduced at last by the increasing of thinning intensity. The gap fraction was positively correlated with opening, direct fixed-point factor, total fixed-point factor, direct radiation under canopy and total radiation under canopy, but negatively correlated with leaf area index. There was a positively significant correlation between transpiration rate, photosynthetic rate and stomatal conductance. After removing the strongest correlation index, the gap fraction was negatively correlated with the photosynthetic rate, and leaf area index had a significant positive correlation with photosynthetic rate. Comprehensive evaluation of characteristics of the light environment in woodland was tested by grey correlation and the correlation degree was 29.00%(0.823)>40.01%(0.794)>53.09%(0.739)>0%(0.724)>67.25%(0.713)>16.75%(0.701)>9.43%(0.673).
      ConclusionThere was correlation between canopy structure and photosynthetic index of larch, and the light transmittance of canopy had obvious influence on photosynthesis rate of undergrowth. Combining the two characteristics of the light environment to evaluate them comprehensively under different thinning intensities, it was best that 29% and 40.01% of thinning in larch natural secondary forest in the light environment. It indicates that intermediate thinning of 29.00%-40.01% is beneficial to the improvement of light environment in the forest.

       

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