Vegetation Response to Climate and Climatic Extremes in Northwest Bangladesh: A Quantile Regression Approach

Abstract The present study assessed the vegetation response to climate in the water-stressed northwest Bangladesh (NWB). The quantile regression analysis was employed to evaluate the effect of climate and climatic extremes on vegetation. The nonparametric correlation analysis was used to assess the climatic influence on vegetation for various time lags. Besides, the modified Mann-Kendall (MMK) test was conducted to understand the changes in climate and vegetation to anticipate the climate change impacts on vegetation. Satellite estimation of Normalized Difference Vegetation Index (NDVI) and observed rainfall and temperature data collected from five locations of the study area for the period 1982-2018 was used for this purpose. The results revealed a negative effect of rainfall, a positive impact of maximum temperature on vegetation in monsoon and a positive influence on minimum temperature on vegetation in winter. Quantile regression analysis revealed a significant negative influence of extreme rainfall and a positive impact of maximum temperature on vegetation for the whole NWB. Overall, the study revealed a greater influence of temperature than rainfall on vegetation change in the region. The trend analysis revealed a reduction in rainfall (-2.56 mm/decade) and a rise in temperature (0.176ºC/decade), and thus, an increase in vegetation (0.014 per decade). The results indicate the positive effect of climate change on vegetation, positively impacting the environment and water resources in the study area.