Allometric Relationship,carbon Assimilation Efficiency Model And Stoichiometry Of Nine Picea Taxa

Metabolic Theory of Ecology (MTE) that describes the relationship of metabolic rate (including: assimilation rate and alienation rate) of plant individuals and body size follows a constant proportional relationship. The allometric exponent has been vigorously debated on Metabolic Theory of Ecology for many years. To test prior theoretical predictions on allomeric relationships among biological traits, a total of nine Picea taxa seedlings were used here to measure aboveground and underground respiration rate, annual net primary productivity, leaves and whole-plant biomass,respectively. Our results showed that 1) in alienation, temperature-corrected average aboveground and underground respiratory rates per plant scaled as 0.869,0.809-power of corresponding biomass per plant respectively, both of which significantly deviated from the three-quarters scaling law predicted by allometric scaling relationship; 2) in assimilation, scaling exponent of average annual net primary productivity per plant versus average leaves biomass per plant was 1.191.Average leaves biomass per plant scaled nearly isometrically (scaling exponent =0,983) with average whole-plant biomass per plant. Both of the allometric exponents mentioned above were close to theoretical prediction value of 1 for small plants; 3)the scaling exponent of average aboveground biomass per plant versus underground biomass per plant (1.074) and temperature-corrected aboveground respiration per plant versus underground respiration rate per plant (1.154) were consistent with the theoretical predictions value of 1, which indicated that the material and energy distribution of aboveground and underground for plant individual were complied by isometric distribution theory without environmental stress. Additionally, we also found that the relationship of annal net productivity per plant and body size scaled nearly 1. These results may provide theoretical references for the evolution of models of metabolic theory.It is generally accepted that increasing CO2 atmospheric levels contribute to global climate change. Accordingly, considerable attention has been paid to how ecosystem productivity and ecosystem assimilation efficiency (EAE) increase naturally. One method is to select species with high seasonal carbon assimilation efficiency (TECA) for reforestation or ecosystem reclamation and then evaluate the TECA of individual species. Here, we developed a theoretical framework based on the metabolic scaling theory to predict the whole growth seasonal carbon assimilation efficiency by directly measuring the whole-plant instantaneous net photosynthetic and dark respiratory rates. Four pivotal predictions of this framework were evaluated using seedlings of nine Picea taxa: (i) the flux rates of CO2 and energy are predicted to scale proportionally (one-to-one) as a function of plant size; (ii) the whole-plant net and gross photosynthetic rates and the net primary productivity are predicted to be directly proportional to the leaf mass; and (iii) these scaling relationships will be independent of temperature regardless of the instantaneous net photosynthetic rate,the instantaneous dark respiratory rate, or the overall growth rate; and (iv) TECA is predicted to conform to an isometric scaling relationship with respect to instantaneous efficiency of carbon assimilation (IECA) such that the latter can be used to predict the former across diverse species in practice. We found that the absolute values of IECA and TECA significantly differed among the nine taxa, with both IECA and temperature-corrected IECA being highest for P. abies and lowest for P. schrenkiana.Our data indicated that the theoretical framework can be used to access seasonal carbon assimilation efficiency of other plant species and can be used to estimate ecosystem productivity and assimilation efficiency.As essential elements for metabolic reactions, both nitrogen and phosphorus are of particular interesting for researchers. Plant investment in nitrogen relative to phosphorus varies with differences in physiological growth strategies among species,while it may follow fundamental stoichiometric rules. In this study, nitrogen and phosphorus contents of roots, stems, leaves and whole plant for seedlings of nine Picea taxa were used to test scaling relationships between these contents and the corresponding organs carbon contents and respiratory rate. Our results demonstrated that 1) the scaling of exponent nitrogen and phosphorus to carbon is not deviating from 1; 2) respiratory rate scales approximately isometrically with nitrogen and phosphorus and 3) isometric scaling of nitrogen to phosphorus per plant is observed in all data. Taken together, these findings provide no support for classic stoichiometric growth model, but gain new insights into the stoichiometric growth model.