Aims Recent theories indicate that N is more in demand for plant growth than P;therefore,N concentration and N:C and N:P ratios are predicted to be positively correlated with relative growth rate(RGR)in plants under n...Aims Recent theories indicate that N is more in demand for plant growth than P;therefore,N concentration and N:C and N:P ratios are predicted to be positively correlated with relative growth rate(RGR)in plants under nutrient-enriched conditions.This prediction was tested in this study.Methods We examined the whole-plant concentrations of C,N and P and RGR,as well as the relationship between RGR and the concentrations and the ratios of N:C,P:C and N:P,for different harvest stages(the days after seed germination)of the seedlings of seven shrub species and four herbaceous species grown in N and P non-limiting conditions.The relationships among plant size,nutrient concentrations and ratios were subsequently determined.Important Findings RGR was positively correlated with N concentration and the ratios of N:PandN:C when the data were pooled for all species and for each shrub species,but not for individual herbaceous species.However,the relationship between RGR and P concentration and P:C was not significantly correlated for either shrubs or herbs.The variation of N among harvest stages and species was much greater than that of P,and the variation in N:P ratio was determined primarily by changes in N concentration.The shrub species differed from the herbaceous species in their N and P concentrations,nutrient ratios and in intraspecific relationships between RGR and nutrient ratios.These differences possibly reflect differences in the capacity for P storage and biomass allocation patterns.In general,our data support recent theoretical predictions regarding the relationship between RGR and C:N:P stoichiometry,but they also show that species with different life forms differ in the relationships among RGR and C:N:P stoichimetries.展开更多
文摘Aims Recent theories indicate that N is more in demand for plant growth than P;therefore,N concentration and N:C and N:P ratios are predicted to be positively correlated with relative growth rate(RGR)in plants under nutrient-enriched conditions.This prediction was tested in this study.Methods We examined the whole-plant concentrations of C,N and P and RGR,as well as the relationship between RGR and the concentrations and the ratios of N:C,P:C and N:P,for different harvest stages(the days after seed germination)of the seedlings of seven shrub species and four herbaceous species grown in N and P non-limiting conditions.The relationships among plant size,nutrient concentrations and ratios were subsequently determined.Important Findings RGR was positively correlated with N concentration and the ratios of N:PandN:C when the data were pooled for all species and for each shrub species,but not for individual herbaceous species.However,the relationship between RGR and P concentration and P:C was not significantly correlated for either shrubs or herbs.The variation of N among harvest stages and species was much greater than that of P,and the variation in N:P ratio was determined primarily by changes in N concentration.The shrub species differed from the herbaceous species in their N and P concentrations,nutrient ratios and in intraspecific relationships between RGR and nutrient ratios.These differences possibly reflect differences in the capacity for P storage and biomass allocation patterns.In general,our data support recent theoretical predictions regarding the relationship between RGR and C:N:P stoichiometry,but they also show that species with different life forms differ in the relationships among RGR and C:N:P stoichimetries.
