Identifying landscape dynamics and ecological imbalances: A geospatial study of Sonadia Island, Bangladesh

Abstract

Sonadia Island, Bangladesh, hosts diverse wildlife, avifauna, and both mangrove and non-mangrove forest ecosystems. However, persistent anthropogenic disturbances have degraded the island's ecological integrity, leading to its designation as an Ecologically Critical Area (ECA) in 1999 to protect vulnerable and endangered species. This study employs an integrated geospatial and socio-economic approach to assess land-use and land-cover (LULC) dynamics, identify associated ecological imbalances, and determine their driving factors. A semi-structured questionnaire survey involving more than 120 local residents was conducted to examine human-environment interactions and prevailing environmental pressures.

Statistical analyses, including Ordinary Least Squares (OLS), Factor Correlation Regression (FCR), Empirical Bayesian Kriging Regression (EBKR), and Principal Component Analysis (PCA), were applied alongside geospatial mapping using satellite imagery from 1990, 2000, 2010, and 2019. The results indicate a substantial expansion of wetlands and sandy or dry soil areas over the past three decades, accompanied by an approximately 51% reduction in mudflat areas, while only 11.5% of the land remained unchanged. The findings also reveal a decline in dense vegetation cover and a corresponding increase in sparse vegetation, suggesting limited potential for vegetation regeneration in sandy or dry soil environments. A SWOT analysis suggests that factors such as limited legal enforcement, reliance on subsistence-based livelihoods, and increasing human activity may be associated with ecological degradation. Ecological imbalance modeling shows that nearly half of the island's area (5287.54 ha) falls within the moderate imbalance class, followed by very high (21.31%) and high (3.31%) categories, with vegetation cover change emerging as a dominant contributing factor. These findings highlight the need for targeted conservation strategies and improved environmental governance to support sustainable management of fragile coastal island ecosystems.