Abstract: To explore the joint regulatory effects of birth time,feeding disturbance,and sexual reproduction of individual lifespan,Artemisia scoparia,a widely distributed species in degraded grasslands in Northeast China,was used as the study object. The reproduction and individual survival characteristics were compared among the experimental populations with different sowing times and decapitation frequencies,as well as natural population under different degrees of grazing disturbance. In the treatment of sowing time,after seeds-setting the experimental populations died entirely of those sown in the early spring and died partly of those sown in the late spring. In the treatment of decapitation,no matter the control or the experimental populations given one or two times of decapitation,all the populations died partly after seed-setting. Delayed sowing time reduced the allocation of inflorescence biomass and seed biomass,but decapitation treatments promoted two kinds of reproductive allocations. In the natural population,the proportion of reproduction allocation of 3-year-old individuals decreased,but the seed production increased,which have a seed quantity 3.6 times that of 2-year-old individuals and 3.1 times that of 1-year-old individuals,respectively. Both the birth time and reproductive allocation strategy of individuals in A. scoparia population affect individual lifespan,and individual death is caused by excessive nutrient consumption during reproduction.

Key words: Seed size, Reproductive strategy, Power-law trade-off, r-K continuum, Reproduction cost

摘要： 为了探讨个体出生时间、采食干扰及有性生殖等过程对个体寿命的调节作用，本试验以东北退化草地广布种猪毛蒿(Artemisia scoparia)为研究对象，开展不同播种时间和不同去顶频次的实验种群，以及不同程度放牧干扰下天然种群繁殖和个体存活特征的比较研究。研究表明：播种时间处理中，早春播种种群结实后当年全部死亡，春末以后播种的结实后部分死亡；去顶处理中，无论是对照，还是1，2次去顶处理结实后均部分死亡；延迟播种时间降低了花序生物量分配和种子生物量分配比例，但去顶干扰对两种繁殖分配均有促进作用；天然种群中，3龄级植株繁殖分配比例下降，但是种子产量增加，分别是2龄级3.6倍和1龄级3.1倍。猪毛蒿种群中个体出生时间和繁殖分配策略都会影响个体寿命，个体死亡是生殖消耗过多养分所致。

关键词: 种子大小, 繁殖策略, 幂律权衡, r-K连续统, 繁殖成本