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Scientia Silvae Sinicae ›› 2022, Vol. 58 ›› Issue (11): 49-60.doi: 10.11707/j.1001-7488.20221105

• Research papers • Previous Articles     Next Articles

Sensitivity Analysis of Ecophysiological Parameters for the Simulated Carbon Flux Using the Biome-BGC Model in a Hippophae rhamnoides Plantation in the Loess Region

Chang Jia1,Lina Wang1,Yakun Tang1,2,*   

  1. 1. College of Forestry, Northwest A & F University Yangling 712100
    2. Institute of Soil and Water Conservation, Northwest A & F University Yangling 712100
  • Received:2021-06-06 Online:2022-11-25 Published:2023-03-08
  • Contact: Yakun Tang

Abstract:

Objective: Sensitivity analysis of the ecophysiological parameters in ecological process models was conducted to improve the accuracy of model simulations by optimizing these parameters. Method: The carbon fluxes observed during 2016-2018 in Hippophae rhamnoides plantation in the Loess Hilly region was used to optimize the parameters of Biome-BGC model and evaluate its applicability and accuracy. The extended fourier amplitude sensitivity test method was used to analyze the first-order sensitivity and total sensitivity of the 27 selected ecophysiological parameters in this model. The effects of these parameters alone or their interactions on the accuracy of simulated carbon fluxes were investigated. The total sensitivity parameters were selected based on high level (> 0.2) and medium level (0.1-0.2) criteria. Path analysis was conducted to calculate the positive and negative effects of these parameters on the Biome-BGC model. Result: The result showed that after optimizing the parameters, the Biome-BGC model was effective at simulating the seasonal dynamics of the carbon fluxes in the H. rhamnoides plantation. Sensitivity analysis indicated that the ratio of new fine root carbon relative to leaf carbon and the ratio of shady leaf area relative to sun leaf area (SLAshade: sun) exhibited high total sensitivity to the gross ecosystem productivity (GEP), ecosystem respiration (RE), and net ecosystem productivity (NEP) in the plantation. The ratio of new fine root carbon relative to leaf carbon also exhibited high first-order sensitivity to the carbon fluxes. Path analysis suggested that the ratio of fine root carbon relative to leaf carbon had significant and negative effects on GEP, RE, and NEP in the H. hamnoides plantation (P < 0.001) through its effects on the relative carbon and nitrogen contents of the leaves and fine roots. In addition, the ratio of shady leaf area relative to sun leaf area had significant and positive effects on the carbon fluxes (P < 0.001) through its effects on the intensity and area of light on the leaves. Both the plant photosynthesis and respiration processes were directly influenced by the relative carbon and nitrogen contents of the leaves and fine roots, and light intensity and area. Conclusion: The ratio of new fine root carbon relative to leaf carbon and the ratio of shady leaf area relative to sun leaf area were highly sensitive parameters to simulate GEP, RE, and NEP through Biome-BGC model in a H. rhamnoides plantation in the loess hilly region. Optimizing these sensitive parameters can improve the accuracy of carbon fluxes simulation of Biome-BGC model.

Key words: Biome-BGC model, carbon flux, Hippophae rhamnoides plantation, sensitivity analysis

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