扎龙湿地不同生境芦苇种群根茎构件的年龄结构

芦苇是典型的长根茎型克隆植物,天然种群主要依靠根茎的营养繁殖进行更新。采用单位土体挖掘取样,按实际生活年限划分根茎龄级的方法,对扎龙湿地芦苇种群不同龄级根茎进行调查。结果表明,6月份,4个生境芦苇种群根茎构件均由2—6a的5个龄级组成,7—10月份均由1—6a的6个龄级组成。6—10月份,1a根茎长度比率逐渐增加;除盐碱生境略有增加外,其他3个生境2a、3a比率均小幅减少;4—6a比率逐渐减小,根茎长度比率均以3a最大,依次是2a,4a,1a,5a,最高的6a最小。1—3a根茎生物量比率逐渐增加;4—6a比率逐渐减小,均以3a根茎生物量比率最大,依次是4a,2a,5a,6a,以最低1a最小。不同龄级根茎长度和生物量比率与返青后实际生长时间之间均较好地符合直线函数关系(R~20.91,P0.01;R~20.81,P0.05),6—9月份,根茎长度呈衰退型年龄结构,10月份又转为稳定型结构,整个生长季根茎生物量均为衰退型结构。不同龄级根茎构件在芦苇种群中的地位和作用不同,根茎构件的年龄结构蕴含着种群调节的重要信息。

Age structure of rhizome module of Phragmites australis population in different habitats in Zhalong wetland

Phragmites australis is a typical clonal plant of long-rhizome, and its natural populations rely mainly on vegetative propagation of rhizomes for renewal. By sampling the soil from a unit area, with method of classifying the age classes of rhizomes according to the actual living years, a field investigation was performed on age structure of rhizome of different age classes of P. australis population in Zhalong wetland. The results showed that the rhizome modules of P. australis populations in four habitats were all composed of five age classes (2nd-6th) in June, and six age classes (1st-6th) from July to October. From June to October, the ratio of rhizome length of 1st was gradually increasing, but the ratio of 2nd and 3rd decreased slightly in three habitats except for the slight increase in saline-alkali habitat. At the same time, the ratio of 4th-6th gradually decreased with the largest ratio of 3rd, followed by 2nd, 4th, 1st, 5th, and the 6th was the smallest. The ratio of rhizome biomass of 1st-3rd was gradually increasing, while gradually decreased between 4th-6th with the largest ratio of 3rd, followed by 4th, 2nd, 5th, 6th, and the 1st was the smallest. The ratio of rhizome length and biomass of different age classes and the actual growth time after turning green were consistent with a linear function (R²>0.91,P<0.01;R²>0.81,P<0.05). The rhizome length showed a declining age structure from June to September, while transformed into a stable age structure in October. The rhizome biomass showed a declining age structure during the whole growing season. The status and function of rhizome module of different age classes were different in the P. australis populations. The age structure of rhizome module contains important information on population regulation.