Developing a grid-based association rules mining approach to quantify the impacts of urbanization on the spatial extent of mangroves in China

Being significant to the coastal sustainability, mangrove forests have decreased at an alarming rate over the past decades, under various pressures from both natural and anthropogenic forces, while urbanization has been widely recognized as one major factor for the dramatic areal mangrove loss. China has experienced rapid urbanization, particularly in coastal zones, which revealed negative impacts towards mangrove loss in previous literature. However, there is a lack of quantitative understanding between urbanization and mangroves loss at large spatial and temporal scales. Given its complexity at a large scale, the relationship between urbanization and mangroves changes remains under-explored, and satellite remote sensing provides a unique tool for addressing this imperative issue quantitatively. To this end, this study developed a grid-based association analysis (GBAA) method for quantifying and investigating the relationship between urbanization and mangroves changes using satellite-derived datasets in China during 1973-2015. Experimental results indicated that conservation policies in nature reserves have made significant contributions to mangrove conservation in China. The impact of urbanization on the spatial extent of mangrove forests weakened gradually outside nature reserves during 1973-2015, indicating that urbanization does not necessarily damage mangroves in recent decades. These findings provide important clues for understanding the relationship between urbanization and mangroves to support better and wiser policy-making for future mangrove conservation and urban management.