紫萁年龄判断及其种群年龄结构分析初探

根据紫萁地下根状茎长度、叶残基痕迹及叶柄基径等与年龄相关的性状特征,该文建立了紫萁年龄判断模型,用以计算广西越城岭地区紫萁种群个体年龄,并采用年龄结构图方法,探讨该地区紫萁种群的年龄结构特征。结果表明:紫萁这种多年生草本蕨类植物达到一定年龄后,地上部分性状趋于稳定,对其年龄判断,只能选择地下根状茎作为研究对象;蕨类植物没有活跃的维管形成层,不能形成完整的次生维管结构,其地下根状茎的直径与年龄之间无显著相关关系,判断其年龄可根据地下根状茎的长度确定。越城岭山脉一带的紫萁种群趋于老龄化,幼龄级个体缺乏,更新能力弱,大量采摘或挖掘紫萁植株,极大地影响了紫萁天然更新和种群结构。

Age estimation and age structure of Osmunda japonica population

Based on the structural characteristics of Osmunda japonica,including the length of subterranean rhizoid,vestige of leaves,diameter of basilar petiolar,a method for age estimation of O.japonica population in Guangxi Yuecheng Ling Region was developed,and the age of each individual was calculated. The approaches of age structure diagram were used to study the age structure of the population. Results revealed that age estimation of O.japonica would focus on its subterranean rhizoid,as its overground part was stable after reaching fixed age; age estimation of ferns would referring to their length of subterranean rhizoid,for they are lack of vascular cambium. O.japonica population in Guangxi Yuecheng Ling Region is aging,Natural regeneration and population structure of O.japonica are tremendously destroyed by excess picking and transplanting.