Abstract

LI, YY et al. Linking relative growth rates to biomass allocation: the responses of the grass Leymus chinensis to nitrogen addition. Phyton (B. Aires) [online]. 2014, vol.83, n.2, pp.283-289. ISSN 1851-5657.

Relative growth rate (RGR) of plants is a key component of fitness. Theoretically, the RGR of plants would be closely related with biomass allocation. Our mechanistic understanding of the relationship between RGR and biomass allocation under global change scenarios is still limited. We examined the responses of RGR and biomass allocation of Leymus chinensis, a dominant grass in the temperate steppe of northern China, to a wide range of N addition. We found that N addition increased RGR of L. chinensis up to a threshold of 10 g N/m². While leaf and stem weight ratios were positively correlated with N addition rates, root weight ratio showed a negative correlation. The RGR of total biomass was positively correlated with both leaf and stem weight ratios, but negatively correlated with root weight ratios. The positive responses of leaf and stem biomass allocation, or the negative responses of root biomass allocation to N addition determined enhancements or reductions, respectively, of RGR on L. chinensis. The increased RGR of L. chinensis to N addition gave a direct and robust explanation for the increased of dominance of this species under field N-addition studies. Our results have important implications for projecting the growth status of L. chinensis under scenarios of increased N deposition in northern China.

Keywords : Plant functional traits; Nitrogen deposition; Growth dynamics; Temperate steppe; Allometry.

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