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Scientia Silvae Sinicae ›› 2024, Vol. 60 ›› Issue (11): 128-138.doi: 10.11707/j.1001-7488.LYKX20230559

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Remote Sensing Recognition Model of Illicium verum Forest Pests and Diseases

Meiqi Li,Meiling Liu*,Xuan Wang,Xiangnan Liu,Ling Wu,Junji Li   

  1. School of Information Engineering, China University of Geosciences (Beijing) Beijing 100083
  • Received:2023-11-22 Online:2024-11-25 Published:2024-11-30
  • Contact: Meiling Liu

Abstract:

Objective: Weak spectral signals induced by pest and disease stress are often obscured by spectral variations caused by vegetation phenology. This study investigates a forest pest and disease monitoring method that enhances weak spectral signals related to vegetation stress, aiming to provide a scientific basis for the prevention and management of forest pests and diseases. Method: Illicium verum was selected as the study species, with Leye County in the Guangxi Zhuang Autonomous Region designated as the experimental area. Sentinel-2 imagery data from 2019 to 2021 were collected for this region. Initially, six vegetation indices sensitive to pest and disease stress responses were selected as preliminary indicators for Illicium verum pest and disease stress: the normalized difference vegetation index (NDVI705), red edge position index (REPI), chlorophyll reflectance red-edge index (CIred-edge), plant senescence reflectance index (PSRI), pigment-specific simple ratio chlorophyll index (PSSRA), and fraction of absorbed photosynthetically active radiation (FAPAR). The Savitzky-Golay (S-G) filtering method was then employed to construct time series curves of these spectral indices. PSRI and FAPAR were identified as the most effective indices for comprehensively characterizing morphological color and physiological changes induced by pest and disease stress in Illicium verum. The Seasonal-Trend decomposition using LOESS (STL) method was applied to decompose the time series of FAPAR and PSRI indices, allowing for the isolation of seasonal components. This facilitated the construction of the Illicium verum Pest and Disease Index (IPDI) by integrating the seasonally adjusted FAPAR and PSRI components. Finally, a monitoring model for pest and disease stress in Illicium verum was developed using the Random Forest algorithm. Result: 1) Compared to healthy vegetation, Illicium verum plantations under pest and disease stress exhibited lower FAPAR and higher PSRI values. 2) The STL method effectively isolates the influence of phenological changes on parameters sensitive to vegetation stress from pests and diseases, thereby enhancing the sensitivity of Illicium verum to stress detection. 3) The remote sensing identification model based on IPDI demonstrated high accuracy, with kappa coefficients and overall accuracies from 2019 to 2021 of 0.81, 0.84, and 0.80, and 87.59%, 88.51%, and 84.17%, respectively. In 2020, the relative error between the remote sensing-calculated damage area of Illicium verum and the statistical disaster area was 2.08%. Conclusion: The method based on enhancing weak spectral signals from vegetation stress effectively monitors the distribution of pest and disease stress in Illicium verum forests. This approach significantly improves control efficiency and supports the sustainable management and ecological conservation of these forests.

Key words: disease and insect stresses, seasonal trend loss method, Sentinel-2 image, spectral index, Illicium verum forest

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