Abstract: Saussurea hieracioides (Asteraceae) is a wide spread species in the eastern margin of Qinghai-Tibetan Plateau. This paper studied the reproductive allocation (RA) strategy of the 18 S. hieracioides populations in 6 altitudinal belts along the elevation from 3200 to 3850 m. The results showed that with increasing altitude, the plant individual size and vegetative input decreased, but the reproductive input increased. The number of disk florets and matured seeds per individual declined, while the weight of disk florets and 100-grain increased with increasing altitude, and there was a tradeoff between the number and weight of both disk florets and matured seeds at individual level. The RA was negatively correlated with the plant individual size among all the populations. It was suggested that in the resources-limited environment, S. hieracioides could increase its tubular floret weight and 100-grain weight at the expense of reducing the number of both tubular floret and seed as one of the strategies to guarantee the success of sexualreproduction.

Key words: intensive management, Phyllostachys heterocycla stand, N₂fixing bacteria, denaturing gradientgel electrophoresis (DGGE), real-time quantitative PCR.