Integrative Biology Journals

JOURNAL OF FORESTRY RESEARCH ›› 2024, Vol. 35 ›› Issue (1): 106-.DOI: 10.1007/s11676-024-01759-x

• Original Paper • Previous Articles     Next Articles

Enhancing forest insect outbreak detection by integrating tree-ring and climate variables

Yao Jiang1,2, Zhou Wang3, Zhongrui Zhang5, Xiaogang Ding5, Shaowei Jiang1,2, Jianguo Huang4,f   

  1. 1 Key Laboratory of Vegetation Restoration and Management of Degraded Ecosystems, Guangdong Provincial Key Laboratory of Applied Botany, South China Botanical Garden, Chinese Academy of Sciences, 510650, Guangzhou, People’s Republic of China
    2 University of Chinese Academy of Sciences, 100049, Beijing, People’s Republic of China
    3 Ministry of Emergency Management of China, National Institute of Natural Hazards, 100085, Beijing, People’s Republic of China
    4 MOE Key Laboratory of Biosystems Homeostasis and Protection, College of Life Sciences, Zhejiang University, 310000, Hangzhou, People’s Republic of China
    5 Guangdong Academy of Forestry, 510520, Guangzhou, People’s Republic of China
  • Received:2023-12-04 Accepted:2024-04-23 Online:2024-10-16 Published:2024-10-16
  • Contact: Jianguo Huang

Abstract:

Annual tree rings are widely recognized as valuable tools for quantifying and reconstructing historical forest disturbances. However, the influence of climate can complicate the detection of disturbance signals, leading to limited accuracy in existing methods. In this study, we propose a random under-sampling boosting (RUB) classifier that integrates both tree-ring and climate variables to enhance the detection of forest insect outbreaks. The study focused on 32 sites in Alberta, Canada, which documented insect outbreaks from 1939 to 2010. Through thorough feature engineering, model development, and tenfold cross-validation, multiple machine learning (ML) models were constructed. These models used ring width indices (RWIs) and climate variables within an 11-year window as input features, with outbreak and non-outbreak occurrences as the corresponding output variables. Our results reveal that the RUB model consistently demonstrated superior overall performance and stability, with an accuracy of 88.1%, which surpassed that of the other ML models. In addition, the relative importance of the feature variables followed the order RWIs > mean maximum temperature (T max) from May to July > mean total precipitation (P mean) in July > mean minimum temperature (T min) in October. More importantly, the dfoliatR (an R package for detecting insect defoliation) and curve intervention detection methods were inferior to the RUB model. Our findings underscore that integrating tree-ring width and climate variables as predictors in machine learning offers a promising avenue for enhancing the accuracy of detecting forest insect outbreaks.

Key words: Forest disturbance, Insect outbreaks, Machine learning, Tree-ring analysis