Mechanical Damage on Abies mariesii Trees Buried below the Snowpack

On a gentle leeward slope in a snowy forest limit in northern Honshu Island, Japan, mechanical damage by snow settlement and creep on Abies mariesii trees buried below the snowpack was examined to detect signs of the snow-damage effect on future survival and crown development. Damage types were recorded based on direct observation of crowns in 1996, a year of high snow accumulation exceeding 4.5 m, and 1997, a year of moderate snow accumulation. Of 153 trees examined, 63% were damaged in 1996 and 15% were damaged in 1997. The most destructive damage type was breakage of stems ≥5 cm in diameter, which occurred on eight trees in 1996 and three in 1997, resulting in foliage loss and death of some trees. The prevalent damage type was branch tearing at branch-stem junctions primarily within a height range of 4–6 m, which occurred on 171 branches in 1996 and 5 in 1997. Under snowy and windy conditions, stem breakage and branch tearing, caused by forces active within restricted layers of the snowpack, may reduce the future survival and crown development of A. mariesii buried below the snowpack in years of heavy snowfall.