Chin J Plant Ecol ›› 2014, Vol. 38 ›› Issue (5): 452-459.DOI: 10.3724/SP.J.1258.2014.00041

• Research Articles • Previous Articles     Next Articles

Trade-off between the biomass and number of flowers in Stellera chamaejasme along an elevation gradient in a degraded alpine grassland

ZHANG Qian,ZHAO Cheng-Zhang(),DONG Xiao-Gang,MA Xiao-Li,HOU Zhao-Jiang,LI Yu   

  1. Research Center of Wetland Resources Protection and Industrial Development Engineering of Gansu Province, College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China
  • Received:2013-12-02 Accepted:2014-03-11 Online:2014-12-02 Published:2014-05-13
  • Contact: ZHAO Cheng-Zhang

Abstract:

Aims Trade-offs are the basis of the theory on plant life-history strategies, and the trade-off between flower size and flower number is an important determinant of flower biomass allocation. Our objective was to study the changes in the relationship between flower size and flower number in Stellera chamaejasme populations with elevation in Northwest China.
Methods The study site was located in a degraded alpine grassland on the northern slope in Qilian Mountains, Gansu Province, China. Survey and sampling were carried out at four elevations at intervals of 100 m from 2700 m to 3000 m; a GPS was used to determine the elevation. Community traits were investigated and 45 individuals of S. chamaejasme were collected randomly at each elevation. The samples were cleaned and divided into different organs, and their biomass were then measured after being dried at 80 °C in an oven.
Important findings With increasing elevation, the height, density, and aboveground biomass of the plant communities displayed a pattern of initial increase and then followed by a subsequent decline; the flower biomass in S. chamaejasme increased with increasing elevation, while the flower numbers decreased. The flower size was negatively correlated with the flower number, but the relationship varied along the elevation gradient; there was a highly significant negative correlation (p < 0.01) between the flower size and the flower number at elevations 2700, 2900, and 3000 m, whereas the correlation only reached a significant level (p < 0.05) at the elevation of 2800 m, indicating that there is a trade-off between the flower size and flower number. The elevation of 2800 m appeared to be a switching point where the S. chamaejasme individuals with more but smaller flowers at the lower elevations were transformed into ones with fewer but bigger flowers with increasing elevation. Consequently, a change in the reproductive strategy with a trade-off between flower size and flower number ensures successful reproduction of the S. chamaejasme populations in adverse environments.

Key words: degraded alpine grassland, elevation, flower number, flower size, Stellera chamaejasme, trade-off