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Chinese Journal of Applied Ecology ›› 2020, Vol. 31 ›› Issue (6): 1916-1922.doi: 10.13287/j.1001-9332.202006.004

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Density and spatial distribution of seedlings and saplings in different gap sizes of a sprucefir mixed stand in Changbai Mountains, China

HE Dan-ni1, YANG Hua1*, WEN Jing2, XIE Rong3   

  1. 1College of Forestry, Beijing Forestry University, Beijing 100083, China;
    2Beijing Xishan Experimental Forest Farm, Beijing 100093, China;
    3Yuhuan Bureau of Natural Resources and Planning, Yuhuan 317600, Zhejiang, China
  • Received:2019-12-27 Online:2020-06-15 Published:2020-06-15
  • Contact: * E-mail: huayang8747@163.com
  • Supported by:
    This work was supported by the National Key R&D Program of China (2017YFC0504101).

Abstract: In August 2019, we investigated natural regeneration (seedlings height between 0.2 m and 1 m; saplings ≥1 m in height and <5 cm in DBH) inside canopy gaps (n=48) in a plot (0.36 hm2) established in a typical mixed spruce-fir conifer broadleaved stand. To examine the short-term effects of gap size (small <20 m2, medium 20-50 m2, large 50-120 m2, and extra large >120 m2) on the regeneration density and growth (height and ground diameter) of Korean pine (Pinus koraiensis), Ezo spruce (Picea jezoensis) and Khingan fir (Abies nephrolepis), the kernel density estimation was used to examine their spatial distribution within gaps. The results showed that spruce and fir regeneration density generally decreased with the increases of gap size (significant effect only on saplings). The density of spruce and fir saplings in small gaps was 0.34 and 1.74 trees·m-2, respectively. In contrast, the density of Korean pine was not affected by gap size. The effects of gap size on seedling and sapling growth were strongest in Khingan fir and weakest in Korean pine, with greater height and ground diameter in larger gaps. Within a given canopy gap, the Korean pine and Ezo spruce saplings in small, medium, and large gaps were taller and had larger DBH in the northeastern corner of the expanded gap than in other sections, whereas those in extra large gaps had the highest growth in the northwestern part of the core gap. Small gaps favoring seed germination and seedling establishment could be created through selective removal of Khingan fir, which should be expanded later to larger sizes (>50 m2) to enhance sapling growth. Further monitoring would be required to understand the long-term effects of gap size on natural regeneration of spruce-fir forest.