Item: BENDING STRESS MODEL FOR SNOW-BURIED TREES: HYSTERSIS EFFECTS OF CROWN SNOW AND ACCUMULATED SNOW LOADING
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Title: BENDING STRESS MODEL FOR SNOW-BURIED TREES: HYSTERSIS EFFECTS OF CROWN SNOW AND ACCUMULATED SNOW LOADING
Proceedings: Proceedings, International Snow Science Workshop, Whistler, BC, Canada, 2026
Authors:
- Daiki Yokoyama [ The United Graduate School of Agricultural Sciences, Iwate University, Iwate, Japan ] [ Faculty of Agriculture, Yamagata University, Tsuruoka, Yamagata, Japan ]
- Takafumi Katsushima [ Tohkamachi Experimental Station, Forestry and Forest Products Research Institute, Tokamachi, Niigata, Japan ]
- Kenichi Yoshimura [ The United Graduate School of Agricultural Sciences, Iwate University, Iwate, Japan ] [ Faculty of Agriculture, Yamagata University, Tsuruoka, Yamagata, Japan ]
Date: 2026-09-28
Abstract: Climate change is projected to increase wet snowfall in regions that continue to receive snow under rising temperatures. Wet snow has a higher water content and density than dry snow, so it accumulates on tree crowns more readily and increases the crown snow load. Snow-buried trees, the understory species and the saplings of canopy species buried within the snowpack, experience greater mechanical strain and higher mortality than snow-exposed trees. Because they are the next generation of the canopy and the understory, their survival directly determines forest regeneration. However, no structural-mechanics-based bending stress model has been developed specifically for snow-buried trees. We developed a bending stress model that accounts for the load hysteresis arising from the sequential application of a crown snow load and a snowpack pressure load. The crown snow load, applied as a concentrated tip load, is the snow that adheres to the crown; the snowpack pressure load, applied as a distributed load, is the force the surrounding snowpack exerts on the buried trunk, including both the weight of the snow and the pressure from its settlement (termed the accumulated snow loading in the title). At each step the trunk form deformed by the previous step was carried over, and the bending stress was calculated from the curvature change using large deformation theory. The model was validated against field measurements from 12 snow-buried Japanese beech, and the agreement was close. Simulations gave two key findings. First, the snowpack pressure load, not the crown snow load, is the direct driver of the bending stress that can break a trunk. Second, an increased crown snow load amplifies the bending stress during the snowpack pressure phase, acting as an indirect but significant risk factor. These results indicate that future increases in the crown snow load driven by wetter snow will indirectly but substantially increase the bending stress in snow-buried trees, with implications for trunk-breakage risk and forest regeneration.
Object ID: ISSW2026_P3.20.pdf
DOI: https://doi.org/10.15788/1790099121
Language of Article: English
Presenter(s): Daiki Yokoyama
Keywords: biomechanics; trunk deformation; large deformation theory; simulation; wet snowfall
Page Number(s): 991 - 994
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