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    采伐对吉林蛟河针阔混交林空间结构的影响

    Effects of thinning intensity on spatial structure of multi-species temperate forest at Jiaohe in Jilin Province, northeastern China

    • 摘要: 探讨不同采伐强度下林分空间结构的变化对森林可持续经营具有指导意义。在吉林省蛟河次生针阔混交林内,设置采伐强度分别为0%(对照,CK)、14.3%(弱度,LT)、29.4%(中度,MT)和50.4%(重度,HT)的4块样地,样地面积各1 hm2,利用角尺度、大小比数、混交度和密集度4个林分空间结构参数探讨林分整体以及春榆、红松、色木槭、水曲柳和紫椴5个主要树种的林分空间结构在采伐3年后的变化。结果表明,从采伐干扰对林分整体的影响来看,LT处理后林分的水平分布格局更合理,混交度较高,林分结构相比CK处理更稳定;采伐干扰对林分大小分化程度的影响不显著;林木密集度随采伐强度增加逐渐降低,林内较稀疏的林木比例逐渐增加;从采伐干扰对主要树种的影响来看,不同树种对采伐干扰的响应差异显著,采伐对5种树种的水平分布格局均有显著影响,但对确定采伐强度不具指导意义;从树种的大小分化程度和混交度考虑,LT处理对春榆、水曲柳和紫椴更有利,MT处理对红松和色木槭更有利;除紫椴外其他树种的密集度随采伐强度的增加而降低。综合考虑,采伐干扰在短期内对林分整体的空间结构影响较小,对主要树种的空间结构影响较大,采伐强度在15%左右比较合理,也可以结合森林经营需求针对个别树种适当提高采伐强度,建议不超过20%。

       

      Abstract: Studying on the differences of spatial structure among different thinning intensity conditions has guiding significance for forest management. Four permanent plots were established in the secondary coniferous and broadleaved mixed forest in Jiaohe, Jilin Province of northeastern China, representing 4 different thinning intensity plots of 0% (control, CK), 14.3% (light treatment, LT), 29.4% (moderate treatment, MT) and 50.4% (high treatment, HT), with 1 ha area of each plot. Three years after thinning, we analyzed the neighborhood pattern, neighborhood comparison, mingling degree and crowding degree of forest, as well as the spatial structure of 5 main tree species, Ulmus davidiana var. japonica, Pinus koraiensis, Acer mono, Fraxinus mandshurica and Tilia amurensis. Our results showed that the horizontal distribution pattern of the whole stand after LT treatment was more reasonable, with higher mingling degree and more stable stand structure than the CK. The thinning has less impact on neighborhood comparison. The crowding degree decreased gradually with the increase of cutting intensity and sparse individual has an opposite result. In terms of the main tree species, the response to logging disturbance was different among species. Although logging had a significant effect on the horizontal distribution pattern of all the five species, the conclusion cannot be used to determine the intensity of logging. In addition, for the neighborhood comparison and mingling degree of these species, LT treatment was more beneficial to Ulmus davidiana var. japonica, Fraxins mandshurica and Tilia amurensis, while ML treatment was better for Pinus koraiensis and Acer mono. Furthermore, the crowding degree of all species decreased with the increase of logging intensity. In conclusion, we find that forest logging has a significant effect on the spatial structure of stands as well as the principal tree species in a short time, and 15% logging intensity is best for formatting a more reasonable stand space structure. We can also consider the forest management needs and increase logging intensity for individual species, but more than 20% logging intensity should not be advocated.

       

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