<正>研究松树幼苗和幼树离体枝对松材线虫侵染的反应，表明组织褐变、失水萎蔫为病害外部症状表现标志；2月龄苗对线虫侵染的反应快速敏感，组织细胞褐变坏死反应明显。而茎已完全木质化的1年生松幼苗和4～5年生幼树离体枝感染松材线虫后，外部症状表现为发病叶褪绿、变红褐色或褐色且萎蔫，症状首先出现在叶基部，很快向叶尖扩展，至整个针叶枯萎死亡。叶部症状的出现标志病害进入发展晚期，寄主已接近完全死亡，茎内失水和细胞褐变坏死已广泛发生。组织细胞褐变坏死反应则直接与线虫的迁移扩散、分布和数量有关。肉眼可见的皮层和髓的褐变通常发生在线虫出现之后，其褐变程度与线虫的数量呈正相关。

The spatial distribution patterns of Broussonetia papyrifera population in the growth stages which naturally revegetabled in mine spoils in Nanjing Mufu mountain were researched by six indices of contagion intensity and the active regulation of spatial distribution patterns of B. papyrifera population was analyzed on the basis of the spectral analysis. It indicated that the spatial distribution patterns of B. papyrifera population in the growth stages which naturally revegetabled in mine spoils in Nanjing Mufu mountain were contagion distribution,and the contagion intensity became weak and turned into a diffuse trend with its growth. It also indicated that the spatial distribution patterns of B. papyrifera population in the stages of seedling and young tree moved regularly based on the spectral analysis.