Abstract: Accurately identifying and monitoring the changes in red mangrove pest and disease outbreaks is of great importance for the protection and restoration of red mangrove ecosystems. In 2023, a serious red mangrove pest and disease outbreak occurred in Tieshan Gang, Guangxi. Using the rapid data acquisition feature of the Huanjing Jianzai-2A/B(HJ-2A/B) satellite (HJ2A and HJ2B), the normalized difference vegetation index (NDVI) and fractional vegetation cover (FVC) parameters were inverted through remote sensing, and a threshold segmentation was performed to obtain the area and degree of damage to the red mangrove forests affected by the pest and disease. The results show that:① In 2023, the maximum area of red mangrove forests affected by pests and diseases in Tieshan Gang was 571.52 hm², accounting for 51.60% of the total area of red mangrove forests in Tieshan Gang.② When 0.1≤FVC≤0.5, the red mangrove forests are affected by pests and diseases. The degree of damage to the affected red mangrove forests was divided into three grades based on FVC, with 0.1≤FVC<0.23 being severe damage, 0.23≤FVC<0.46 being moderate damage, and 0.46≤FVC≤0.5 being light damage. Among them, the red mangrove forest with severe damage on October 8, 2023 was 257.82 hectares, accounting for 45.11% of the total affected red mangrove forest area at that time.③ On October 8, 2023, the area of red mangrove forests affected by pests and diseases in Tieshan Gang was the largest and the degree of damage was the most severe.

Key words: HJ-2 Satellites, Mangroves, Pests and Diseases, Dynamic Monitoring, Tieshan Port