Effects of Seedling Size, Stock Type, and Mechanical Site Preparation Method on Initial Survival and Growth of Japanese Larch (Larix kaempferi) Seedlings

Abstract

It is important to understand the characteristics of Japanese larch (Larix kaempferi) seedlings that allow them to grow vigorously after planting and quickly exceed the height of surrounding vegetation, resulting in lower weeding costs. Seven stock types, including bareroot and container-grown seedlings, were planted in two plots with different mechanical-site-preparation (MSP) methods and evaluated for survival, height, and root collar diameter (RCD) for four consecutive years. Three-year-old bareroot seedlings, which were one year older and larger than normal, had low survival rates in the mulcher MSP. Initial seedling height significantly differed among the seven stock types, while almost no significant differences were observed after four growing seasons. Model analyses showed that initial seedling height and RCD had a significant effect on seedling height after planting until the second growing season, while the effect of planted seedling age and plot became increasingly significant after the third growing season. The difference in seedling type, bareroot versus container-grown seedlings, had no effect on the seedling height during the four growing seasons after planting. A decision tree analysis suggests that the seedlings with sufficiently large RCD and young age, regardless of seedling type, can grow taller than surrounding vegetation more quickly.

Eight-year survival and growth of Sakhalin fir (Abies sachalinensis) seedlings with one weeding operation: Impact of mechanical site preparation, vegetation release, summer planting, stock type, and forwarder trail

“…Equivalently sized container seedlings can perform equally well (Thiffault et al 2014) or even outperform bareroot seedlings (Morrissey et al 2010). The smaller container seedlings with a higher H:D ratio at planting tend to prioritize diameter growth over height until reaching a more balanced ratio (Yagihashi et al 2016;Ivetic et al 2017;Harayama et al 2023a). In this study, container seedlings with higher H:D ratio (Fig.…”

“…This approach serves as a chemical herbicide alternative on a global scale (Thiffault and Roy 2011;Löf et al 2012;Fargione et al 2021). In Japan, MSP is occasionally implemented through topsoil scari cation using an excavator-mounted bucket and mulching with a forest mulcher attached to an excavator for postlogging vegetation management (Yamada et al 2018;Oya et al 2021;Harayama et al 2023a), although manual site preparation remains predominant. In birch forests where the upper trees had been lost due to logging or natural disturbances in Hokkaido, both bucket scari cation MSP and mulching MSP have effectively suppressed dwarf bamboo regeneration, enabling the emergence of deciduous perennials and shrubs, previously sti ed by dense dwarf bamboo cover (Yamazaki and Yoshida 2020;Harayama et al 2023b).…”

“…Various factors in uence seedling survival and growth during reforestation, including seedling type and quality (Grossnickle and El-Kassaby 2016;Grossnickle and MacDonald 2018a;Harayama et al 2023a), as well as soil compaction resulting from heavy forestry vehicle use (Cambi et al 2015;Labelle et al 2022). In Japan, the past decade has seen the introduction of container seedlings, aiming to extend the Subsequently, two MSP methods were applied: 0.5 m 3 capacity bucket scarifying MSP (PC120, Komatsu Ltd.) or mulching MSP (MINI-BMS 125, Seppi, Mezzolombardo, Italy) using excavators (Figure S2).…”

Eight-year survival and growth of Sakhalin fir (Abies sachalinensis) seedlings with one weeding operation: Impact of mechanical site preparation, vegetation release, summer planting, stock type, and forwarder trail

“…3c). Seedlings with a heightened H:D ratio defer height growth in favor of diameter growth until an appropriate H:D ratio is attained (Yagihashi et al, 2016;Ivetic et al, 2017;Harayama et al, 2023a). In this study's second year, container seedlings displayed high RGR D (Fig.…”

Research on Morphological Indicator Extraction Method of Pinus massoniana Lamb. Based on 3D Reconstruction

“…The quality of P. massoniana seedlings directly affects the success of afforestation, operational costs, and economic benefits. Therefore, employing scientifically sound methods for evaluating seedling quality is a crucial mean of ensuring the production of superior seedlings [5,6].…”