Assessing the characteristics and seasonal changes of mangrove forest in Dong Rui commune, Quang Ninh Province, Vietnam based on multispectral UAV data

Abstract

Mangroves are estuarine and coastal ecosystems strongly influenced by the local tidal regime and climate, so there is a strong variation between seasons of the year. Assessing seasonal characteristics and fluctuations allows for an understanding of changes in mangrove ecosystems during each period of the year. In this study, we used images collected from the Multispectral Unmanned Aerial Vehicle (UAV) to determine the current status and fluctuations between summer and winter of the mangrove area of Dong Rui commune according to five vegetation indicators, including the Normalized Difference Vegetation Index (NDVI), Green Normalized Difference Vegetation Index (GNDVI), Enhanced Vegetation Index (EVI), Visible Atmospherically Resistant Index (VARI), and Green Chlorophyll Index (GCI). The results show that the current state of mangroves in the UAV flight area is relatively good, with the value of vegetation indicators at a high level. In the summer, the value of vegetation indicators is stable and higher than in the winter. In low-tide areas, vegetation index values fluctuate higher than in high-tide areas. Based on the results of the analysis of vegetation indicators, the degree of correlation between NDVI and the remaining four values was determined. The results showed that the correlation coefficient was at a high level, with the highest being between NDVI and SAVI with a correlation coefficient of approximately equal to 1, followed by NDVI and EVI with a correlation coefficient above 0.9. We propose that UAV is an effective tool for monitoring and assessing fluctuations, serving the management and conservation of mangrove ecosystems.