关键词: 水曲柳, 蒙古栎, 林隙大小, 人工更新, 生长, 形态, 生物量

Abstract: [Objective] This study was aimed to investigate the long-term effects of gap size on growth, morphology and biomass accumulation in planted Quercus mongolica and Fraxinus mandshurica saplings, and provide a scientific support for artificial regeneration.[Method] Random sampling method was used to survey the growth, morphological characteristics and biomass allocation in planted young trees of 15-year-old Q. mongolica and 9-year-old F. mandshurica with different gap sizes in the forest, i.e., large, intermediate, small gaps, and closed canopy, in Changbai Mountains, Jilin province, China.[Result] The height, ground-diameter, crown length and crown width of Q. mongolica and F. mandshurica saplings were significantly decreased with decreasing gap size (P < 0.05). The length and basal diameter of first-order-branches were significantly decreased with decreasing gap size of Q. mongolica and F. mandshurica saplings (P < 0.05), while density of first-order-branches and the branching angles were increased. The leaf length, leaf width, average leaf area and leaf area index of Q. mongolica and F. mandshurica saplings decreased with decreasing gap size. However, the specific leaf area decreased at first, followed by an increase with decreasing gap size. With the decrease of gap size, total biomass were significantly decreased (P < 0.05),the root-shoot ratio of Q. mongolica saplings gradually decreased, while the root-shoot ratio of F. mandshurica saplings decreased at first and then followed by an increase.[Conclusion] The larger gap size tend to promote growth of the 15-years-old Q. mongolica and 9-yeard-old F. mandshurica saplings; while smaller gap size and closed canopy habitat inhibited the saplings' growth. The effects of gap size on planted saplings can last for a long period, and it is necessary to evaluate the long-term accumulated growth responses of the saplings growing in different gaps. Effects of gap size on the growth of Q. mongolica saplings were greater than that on F. mandshurica saplings, suggesting that larger sized gap is more suitable for the artificial regeneration of Q. mongolica.

Key words: Fraxinus mandshurica, Quercus mongolica, gap size, artificial regeneration, growth, morphology, biomass