Abstract:

Accurately identifying and monitoring the changes in mangrove pest and disease outbreaks is of great importance for the protection and restoration of mangrove ecosystems. In 2023, a serious mangrove pest and disease outbreak occurred in Tieshan Port, Guangxi. Using the rapid data acquisition feature of the Huanjing Jianzai-2A/B (HJ-2A/B) satellites, 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 mangrove affected by pests and diseases. The results are shown as follows. (1) In 2023, the maximum area of mangrove affected by pests and diseases in Tieshan Port was 571.52 hm², accounting for 51.60% of the total area of mangrove in the port. (2) When 0.1≤FVC≤0.5, the mangrove was affected by pests and diseases. The degree of damage to the affected mangrove 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 mangrove with severe damage on October 8, 2023 was 257.82 hm², accounting for 45.11% of the total affected mangrove area at that time. (3) On October 8, 2023, the area of mangrove affected by pests and diseases in Tieshan Port was the largest and the degree of damage was the most severe.

Key words: HJ-2A/B satellites, mangroves, pests and diseases, dynamic monitoring, Tieshan Port