Spatiotemporal interactions between climate extremes and vegetation in the Southwestern Region of Bangladesh

Increased frequency of extreme temperature and precipitation events is now major concerns. These events threaten both natural vegetation growth and the frequency of disasters in a country characterized by flat deltaic topography and a subtropical monsoon climate. This study assessed the association between eight precipitation and temperature extreme indices and vegetation cover to evaluate and understand the relationship between climate extremes and natural vegetation growth. Remote sensing and meteorological data were collected from six weather stations in the southern region from 1992 to 2022. Climate variability was measured by calculating climate extreme indices using the R program, and change detection of vegetation cover was conducted using Normalized Difference Vegetation Index (NDVI). Mann-Kendall and Sen’s slope were used to analyze the trends in NDVI and climate extreme indices. The spatial heterogeneity of vegetation cover was analyzed by comparing NDVI results of years within a five-year gap, while the spatial heterogeneity of climate extreme indices was assessed using interpolation methods. Also, the annual mean NDVI has a significant increasing trend at a rate of 0.002 year⁻¹ (R² = 0.1726, p = 0.014), while warm temperature indices showed a significant rise and had a negative correlation with NDVI. Intense and heavy precipitation-related indice (R20mm) also showed a negative correlation with NDVI, as intense and heavy rainfall causes floods that damage vegetation. This knowledge helps policymakers assess vegetation vulnerability to climate fluctuations and supports the development of mitigation and monitoring programs, enhancing ecological conservation, land use planning, and forest management.