The 30-year impact of post-windthrow management on the forest regeneration process in northern Japan

Abstract

The frequency and intensity of typhoons are expected to increase over time due to climate change. These changes may expose forests to more windthrow in the future, and increasing the resilience of hemiboreal forests through forest management after windthrow is important. Here, we quantified forest structure recovery using aerial photos and light detection and ranging (LiDAR) data after catastrophic windthrow events. Our aims are to test the following three hypotheses: (1) forest structure will not recover within 30 years after windthrow, (2) forest recovery will be affected not only by salvaging but also pre-windthrow attributes and geographical features, and (3) various post-windthrow management including salvaging will drastically alter tree species composition and delay forest recovery. Our results revealed that hypothesis (1) and (2) were supported and (3) was partially supported. The ordination results suggested that more than 30 years were needed to recover canopy tree height after windthrow in hemiboreal forests in Hokkaido, Japan. Salvage logging did not delay natural succession, but it significantly decreased the cover ratio of conifer species sites (0.107 ± 0.023) compared with natural succession sites (0.310 ± 0.091). The higher the elevation, the steeper the site, and the higher the average canopy height before windthrow, the slower the recovery of forest stands after windthrow and salvaging. Scarification and planting after salvage logging significantly increased the number of canopy trees, but those sites differed completely in species composition from the old growth forests. Our study thus determined that the choice and intensity of post-disturbance management in hemiboreal forests should be carefully considered based on the management purpose and local characteristics.

The natural ‘exclosure effect’ and tree regeneration following post‐windstorm salvage logging

“…The greater abundance of Abies balsamea regeneration relative to that of Picea rubens , even in Picea rubens dominated stands, is well reported given that its regeneration is more robust and responds more aggressively to large canopy openings than does Picea rubens (Dumais & Prévost, 2014; Seymour, 1992). Similar compositional and structural differences between blowdown and salvage treatments are well documented in previous salvage logging studies (Li et al., 2023; Royo et al., 2016; Taeroe et al., 2019). However, we acknowledge a potential bias in our study (as well as in most previous browsing studies): Seedlings that had been completely consumed would not have been tallied, as no part would have been visible (Mosbacher & Williams, 2009).…”

“…Results from our study system indicate that salvage logging simplified CWM structure and altered regeneration structure and composition relative to blowdown conditions. These alterations, evident early in stand development, may influence forest structure and composition for decades, as seen in previous studies (Li et al, 2023;Mabry & Korsgren, 1998;Sass et al, 2018). Further, results suggest that retaining post-blowdown CWM in situ created an exclosure effect, thereby protecting saplings from browsing.…”

“…Although primarily conducted to reduce timber revenue losses, salvage logging has also been used to aid in site preparation (Greene et al., 2006), to abate future disturbance risk (bark beetle outbreaks, fire severity) (Dodds et al., 2019; Fraver et al., 2011; Johnson et al., 2013) and to promote coexistence of important hardwood tree species (Royo et al., 2016). In contrast, salvage logging has been shown to impede tree regeneration (D'Amato et al., 2011; Santoro & D'Amato, 2019), reduce plant community diversity (Kleinman et al., 2017; Leverkus et al., 2014), eliminate the aerial seedbanks of serotinous species (Greene et al., 2006) and slow post‐disturbance recovery (Li et al., 2023; Taeroe et al., 2019). These negative aspects of salvage logging are often centred around the loss of coarse woody material (CWM), given that standing and downed wood left after disturbance enhances forest structure, stimulates nutrient cycling and provides substrate for regeneration, among other benefits (Lindenmayer et al., 2004).…”

Improving the Estimation of Structural Parameters of a Mixed Conifer–Broadleaf Forest Using Structural, Textural, and Spectral Metrics Derived from Unmanned Aerial Vehicle Red Green Blue (RGB) Imagery

“…The arboretum experienced mean annual temperature of 6.4 • C and annual precipitation of 1297 mm (230 m asl) during 2001-2008. Snow typically covers the forest floor from late November to early April, reaching approximately 1 m in depth [34,[44][45][46]. For this study, forest compartments 16 (com16) and 65-66 (com65-66) were selected as the study area (Figure 1).…”

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

“…In birch forests where the upper trees have been lost due to logging or natural disturbances in Hokkaido, both bucket scarification MSP and mulching MSP have effectively suppressed dwarf bamboo regeneration, enabling the emergence of deciduous perennials and shrubs, previously stifled by dense dwarf bamboo cover [31,32]. As Sakhalin fir is highly shadetolerant [33][34][35], similar to other American and European Abies species [36,37], its seedlings' survival and growth may be less impacted by deciduous vegetation compared with evergreen dwarf bamboo. Thus, applying MSP across the plantation and restraining dwarf bamboo regeneration could substantially curtail the need for frequent weeding in Sakhalin fir plantations.…”