Effects of deer debarking on masting and trunk radial growth of Hondo spruce, Picea jezoensis var. hondoensis, in a subalpine forest of central Japan

摘要

To examine whether Hondo spruce (Picea jezoensis [Sieb. et Zucc.] Carriere var. hondoensis [Mayr] Rehder) exhibits masting and how cone production and growth are affected by debarking by sika deer (Cervus nippon [Temminck]), cone production was followed over a 10-year period (1993-2002) in an old-growth subalpine forest in Mt. Ohdaigahara, central Japan. The trees showed high annual variation in cone production and masting production was seen twice in 1995 and 2002. The maximum mean number of cones per tree was 82.1 in 1995, followed by 35.8 in 2002. The coefficient of variation (CV) for the mean number of cones was 1.74. Very few cones were observed in other years. Significant positive relationships were detected between the mean number of cones and percentages of cone-producing trees, suggesting that Hondo spruce has normal masting behavior. Masting in debarked and untouched trees was synchronized, suggesting bark stripping does not affect cone production and masting by Hondo spruce. Debarking did not affect trunk radial growth and a trade-off was not detected between cone production and radial growth in mast years.