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Scientia Silvae Sinicae ›› 2019, Vol. 55 ›› Issue (11): 145-152.doi: 10.11707/j.1001-7488.20191116

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Nondestructive Estimation of Total Phosphorus Content in Canopy Leaves of Young Dalbergia odorifera

Zhulin Chen1,Xuefeng Wang1,*,Qingjun Guan2   

  1. 1. Research Institute of Forest Resource Information Techniques, CAF Beijing 100091
    2. Moerdaoga Forestry Bureau, Inner Mongolia Erguna 022250
  • Received:2019-03-01 Online:2019-11-25 Published:2019-12-21
  • Contact: Xuefeng Wang
  • Supported by:
    国家自然科学基金项目(31670642);林业科学技术推广项目([2016]11号)

Abstract:

Objective: In this paper, the total phosphorus content of young Dalbergia odorifera leaves in per unit-mass was estimated by using the image understanding method with the tree image as the data source. Method: Firstly, the algorithm which was used to extract the canopy image of Dalbergia odorifera from the image is provided. Then the statistical model form and the effective image parameters used to estimate the total phosphorus content of leaves are constructed. Finally, the plant leaf total phosphorus content prediction model with image parameters as independent variables is established by using nonlinear mixed-effects model. Result: Based on the color difference between foreground and background, this paper proposes a simple method to extract canopy image with green rate. Through a large number of image tests, we know that it can effectively erase the background when the green rate is set between 0.35 and 0.42. Furthermore, we combined and analyzed the image parameters, and built the nutrient content estimation model. The leaf total phosphorus content prediction model is established, which takes the standardized gray value as indicators and adjusts them with the the warm data. The model can achieve a high precision estimation of the phosphorus content per unit weight of canopy leaves. At the same time, the random effects are introduced to the model parameter estimation, and the results show a good adaptability to the prediction of total phosphorus content of Dalbergia odorifera with different soil c onditions in different regions. Conclusion: The result indicate that the green rate is a good method for tree crown image segmentation and extraction when there exist a certain difference between the background and foreground. The two-image parameter model could effectively improve the estimation accuracy of total phosphorus content prediction. For the prediction of total phosphorus content in canopy leaves of Dalbergia odorata with different soils or environments in different regions, the mixed effect model integrates these differences into one model, and shows a strong adaptability.

Key words: Dalbergia odorifera, image understanding, image extraction, mixed effects model, phosphorus content estimation

CLC Number: