Etiology of “Shimagare” dieback and regeneration in subalpineAbies forests of Japan
Etiology of “Shimagare” dieback and regeneration in subalpineAbies forests of Japan
复制标题
日本亚高山冷杉林“Shimagare”枯死的病因和再生
作者：
T. Kohyama
“雪马瑞”现象与日本中部亚高山冷杉(Fir)森林中林分水平枯萎的条纹模式有关。死亡线逐渐变成纯净的冷杉林。随着死亡区的前进，它们会随着以波浪形式出现的偶数年龄段的艾比斯而再生。这种现象主要发生在靠近山顶的南坡上，使死皮前锋向南(即向下)暴露。几个事实表明，盛行风加速的干燥应力和机械破坏引发了人工林的定向枯死。然而，死亡线是由过度拥挤和均匀大小的看台结构推动的。在更新的早期阶段，当耐荫性较差的桦树入侵时，就会形成混交林。这些硬木混交林，不那么拥挤，种群大小不一，几乎不会同时腐烂。在这里，树也变得更大，活得更长。因此，大量枯死的趋势不是该物种本身的特征，而是该物种的致密纯林分的特征之一。
The “Shimagare” phenomenon relates to a striped pattern of stand-level dieback in the subalpineAbies(fir) forest of central Japan. Dieback fronts move gradually into pure stands ofAbies. As the dieback zones move forward they become regenerated with even-aged cohorts ofAbieswhich come up in form of waves. The phenomenon occurs mostly on the south slopes near mountain tops, exposing dieback fronts to south (i.e. downwards). Several facts suggest that desiccation stress and mechanical damage accelerated by the prevailing wind trigger the directional dieback ofAbiesstands. The dieback is, however, promoted by over-crowded and even-sized stand structure. When less shade-tolerantBetula(birch) trees invade in an early stage of regeneration, mixed stands develop. These hardwood-mixed stands, with less-crowded and various-sizedAbiespopulations, hardly decay simultaneously. Here, alsoAbiestrees become larger and live longer. Thus, the tendency of mass dieback ofAbiesis not a characteristic of the species as such, but rather one of dense pure stands of the species.