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Aboveground biomass modeling and allometric growth characteristics of Artemisia capillaris Thunb. under different water availabilities.

LI Lang1,2, LI Yi-bo1,2, MA Quan-hui1,2, YU Hong-ying1,2, LIU Xiao-di1,2, QI Miao1,2, XU Zhen-zhu1*   

  1. (1State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; 2University of Chinese Academy of Sciences, Beijing 100049, China).
  • Online:2020-01-10 Published:2020-01-10

Abstract: Establishing plant biomass models to explore plant allocation strategy and allometric growth relationships under various environments is of importance for better understanding plant community structure and function, and the storage and allocation mechanism of carbon. An in situ field experiment was conducted to examine the effects of water availability on plant biomass and allocation strategy in a desert steppe in northern China. Several key but easily measured parameters of a common species, Artemisia capillaris Thunb., in the desert steppe, including height, basal diameter, number of branches, crown, and biomass under different precipitation levels were used to construct plant biomass models. The allometric growth relationship of A. capillaris was analyzed using a standardized major axis regression. The results showed that the optimal parameters for biomass models along the gradient of water availability changed a lot. The allometric growth relationships within plant organs and that between plant organ and aboveground biomass were quite discrepant, with isometric growth relationships under extremely increased and decreased 50% precipitation amounts relative to the ambient. It indicated that there was a tradeoff of carbon allocation between plant organs under different water conditions, in accordance with the hypothesis of the best optimal resource allocation. However, the allocation competition may attenuate under extreme climatic conditions. The findings suggest that it is necessary to incorporate environmental factors such as precipitation for conducting biomass models of herbs in desert steppe. Our results can provide methodological support and theoretical basis for constructing biomass assessing models and understanding the adaptation of allometric growth to environment for herbs in arid ecosystems.

Key words: yield., direct-seeded cotton after wheat harvest, nitrogen application rate, potassium uptake and utilization