狼毒种群生殖构件数量特征与生殖配置研究

研究了内蒙古东部退化草原3个放牧演替阶段内狼毒种群的生殖构件数量特征、生殖配置及其与年龄的关系.结果表明,极牧阶段每株花序数、每花序花蕾数、每花序花数显著高于重牧、过牧阶段(P<0.05),而千粒重在3个演替阶段之间差异不显著(P>0.05);6～14龄植株的花蕾数、花数、种子数随着年龄增大而增加,自15龄以后趋于稳定;老龄植株仍保持一定的繁殖能力.狼毒种群最小生殖年龄为6龄,最大生殖年龄为19龄;在同一个演替阶段内,均以花期的生殖配置值最高;地上生物量生殖配置平均为8.62%,茎、叶、生殖构件的总体配置格局为茎∶叶∶生殖构件＝5∶6∶1.放牧干扰未对狼毒种群的生殖配置格局产生显著影响;相对稳定的低生殖配置和长寿命可能是有利于该种群的生存与延续的生活史策略.

Study on the demography of reproductive modulars and reproductive allocation of a Stellera chamaejasme population

The quantitative characteristics of reproductive modulars (RM), reproductive allocation (RA) and the relation between the traits and the ages of a S. chamaejasme population which were distributed over three grazing successional stages (GSS), have been studied, with the results presented in this paper. The populations were located on the degraded steppe of eastern Inner Mongolia, China. The three GSS were defined as either over, heavy or extreme. The results show that: (1) the number of inflorescences per individual, number of flower buds per inflorescence and number of flowers per inflorescence of the population in the extreme GSS was significantly higher (P<0.05) than that in the heavy and over GSS, however the 1000-seed weights did not differ significantly (P>0.05) between the three GSS; (2) the number of flower buds, flowers, and seeds per individual in the 6-14 year olds increased with aging before stabilizing from 15 years old onward; (3) the RA value in the flowering stage was higher than in both the flower bud and fruiting stages within the same GSS; (4) the youngest reproductive age of the individuals was 6 years old and the oldest 19 years, with considerable fecundity found in older individuals; (5) the total mean RA value of aboveground biomass was 8.62% and the RA pattern of stemleafRA of the population was 561, with RA shown to be non-significantly affected by grazing disturbances. Stabilization of a lower RA and longevity of individuals were possibly survival strategies of S. chamaejasme, which were favorable to higher survival rates and consequently the proliferation of the population.