Abstract

Mangrove vegetation is among the most threatened and vulnerable ecosystems in the world, which has experienced a rapid decline over the past few decades. The dynamics of Mangrove vegetation in Quy Nhon city has been almost unnoticed and monitored since 1975, although the area has decreased significantly in the early years of the 21^st century. Therefore, the objectives of our study were to quantify changes in mangrove vegetation and identify the dominant drivers of change in Quy Nhon city, Binh Dinh province in the period 1975-2020. Spatial and temporal changes of mangrove vegetation were extracted using an object-based classifier combined with spectral index (CMRI) and support vector machine (SVM) algorithms in optical remote sensing images. The results show that the mangrove vegetation area of Quy Nhon city has significantly decreased by 8.26% during the 45 years and different degrees of decline in periods 1975-1995, 1995-2005, 2005-2010, and 2010-2020. In which, the period 1995-2005 has the largest decrease of 297.56 ha with an annual reduction rate of 29.75%/year. The findings of this study highlight the need for frequent and continuous monitoring of mangrove vegetation for a coastal city in the context of the impact of climate change and the rapid urbanization process.