Assessing long-term vegetation changes, pollution and climate response in the Uttarakhand Region, North India:...

Analyzing vegetation dynamics in the Himalayan region has been challenging due to the limited ground observations and complex topography. This research focuses on examining the spatiotemporal variability of vegetation cover in Uttarakhand State, northern India, over a 22-year period (2001-2023), by exploring the relationships between two vegetation indices-Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI)-and various climatic and pollution factors. These factors include Evapotranspiration, soil moisture, precipitation, land surface temperature, number of forest fires, aerosols, Black Carbon, ozone, sulfur oxides, and land use-land cover. The present study utilized Google Earth Engine to enable detailed monitoring of vegetation patterns. Pearson correlation coefficients were employed to analyze the relationships between vegetation indices, climate, and pollution variables. The results showed that the average NDVI and EVI peaked during the post-monsoon season and were lowest in the pre-monsoon. Significant monthly, seasonal, and inter-annual variations in these indices were observed, highlighting distinct effects of climatic variables on vegetation development across regions. Anthropogenic pollutants like aerosols, BC, sulfate, and O₃ may affect vegetation indices to a lesser degree, depending on the district and altitude. Multi-decadal trends in NDVI and EVI revealed district-wise tendencies, exhibiting a general increase in vegetation indices across the state. This research enhances the understanding of climate-vegetation interactions in mountainous ecosystems highly impacted by atmospheric pollution, contributing valuable insights about vegetation-climate-human interactions. By understanding specific climatic and anthropogenic factors that affect mountainous ecosystems, decision-makers can implement targeted strategies to mitigate their adverse effects.