藏北高原不同海拔四川嵩草克隆种群表型和繁殖对策

The clonal phenotypic variation and reproductive strategies of Kobresia setchwanensis along altitude in Northern Tibet

本研究通过野外调查和室内分析相结合的方法分析了不同海拔四川嵩草(Kobresia setchwanensis)克隆种群相关特征的差异,研究结果表明,海拔高度显著影响四川嵩草克隆种群的特征参数、生物量及分配和种子萌发率(P<0.05);藏北草甸四川嵩草的最适分布海拔为4 400 m左右,随海拔的升高,四川嵩草株高、分株数以及生物量积累都呈现下降的趋势;繁殖枝数、穗粒数、萌发率等有性繁殖指标随海拔高度的升高而降低,但千粒重维持相对稳定;随海拔高度的增加四川嵩草将更多的生物量分配至克隆繁殖器官,因此在海拔高度变化的过程中四川嵩草有性繁殖和克隆繁殖之间存在权衡,随海拔高度的增加四川嵩草表现出逐步降低有性繁殖投入(穗重比降低)而增加克隆繁殖投入(根状茎重比增加)的策略。

The phenotypic and reproductive characteristics of Kobresia setchwanensis were investigated and analyzed in order to understand the clonal phenotypic variation and reproductive strategies of this species along altitude in Northern Tibet. For the clonal phenotypic parameters,there were significant differences among populations from different altitudes. The most suitable altitude for K. setchwanensis was about 4400 m above sea level in Northern Tibet. With the increase of the altitudes,the plant height,ramet number and biomass accumulation of K. setchwanensis decreased. The number of reproductive branches and grains per spike,the germination rate and biomass allocation also decreased with the increase of altitude which suggested that there was a trade-off relationship between the sexual reproduction and the clonal reproduction of K. setchwanensis. The results suggested that K. setchwanensis gradually reduced input of the sexual reproduction while increased input of the clonal reproduction to maintain and expand the population with the increase of the altitude.