Effects of simulated warming on the allometric growth patterns of an alpine meadow community on the Qinghai-Tibet Plateau

An alpine meadow on the Qinghai-Tibetan Plateau was chosen as the research object. In the meadow, simulated warming experiments were conducted using infrared radiators, and community growth characteristics were investigated during the plant growing seasons of 2011−2013 and 2016−2018. Four common basic functions (exponential, linear, logarithmic, and power functions) were selected to fit the optimal equations to analyze the allometric relationships of the plant communities under control and warming treatments and explore the effects of the simulated warming on the allometric relationships of the meadow plant communities on the plateau. The results showed that: 1) In the control treatment, the aboveground biomass was significantly and positively correlated with density (P < 0.05), height (P < 0.01), and cover (P < 0.01), whereas in the warming treatment, the aboveground biomass was significantly and positively correlated with frequency (P < 0.01) and cover (P < 0.01), and the root-shoot ratio was significantly negatively correlated with density (P < 0.05) and cover (P < 0.05); 2) The effect of cover on the aboveground biomass increased under the warming treatment (P < 0.01), the effect of frequency on the aboveground biomass changed from insignificant (P > 0.05) to significantly positive (P < 0.01), and density and cover effects on the root-shoot ratio changed from insignificant (P > 0.05) to significantly positive (P < 0.01). The density and cover effects on the root-shoot ratio also changed from insignificant (P > 0.05) to significantly negative (P < 0.05); and 3) Among the four common basic functions, the power function was more consistent with the vegetation growth relationship, indicating that meadow vegetation conformed to the allometry theory. In the control treatment, the aboveground part of the meadow vegetation was in agreeance with the isometric relationship, the belowground part with the allometric relationship, and the overall meadow vegetation with the allometric relationship. In the warming treatment, the aboveground part, belowground part, and overall meadow vegetation all conformed to the allometric relationship. Therefore, the aboveground part of the meadow vegetation changed from an isometric relationship to an allometric relationship, and the belowground part of the meadow vegetation further enhanced the allometric relationship under the warming treatment. The results of this study have theoretical significance for accurately understanding how climate change affects plant growth and community structure in alpine meadows.