Assessing Landslide-Driven Deforestation and Its Ecological Impact in the Western Ghats: A Multi-Source Data Approach

Abstract

The influence of landslides (LS) on forest structure, composition, and functionality has gained limited scientific attention compared to socioeconomic aspects. This study aims to fill this gap by investigating the dynamics of pre- and post-LS occurrences in and around the Kali Tiger Reserve (KTR), Western Ghats. Our approach integrates multi-source, multi-temporal earth observation data, vegetation indices, field observations, and machine learning techniques. This study identified 245-LS caused due to a catastrophic rainfall event in July 2021 the most severe over a century that impacted the tropical dense forests. The present study highlights the emergence of invasive alien species (IAS), particularly Chromolaena odorata, following these landslide incidents. Field observations revealed a significant loss of large trees, which corroborated with the Global Ecosystem Dynamics Investigation (GEDI) based Canopy Height Model (CHM) and very high-resolution (VHR) data. The affected areas witnessed a significant rise in land surface temperature (LST) and a decrease in vegetation moisture. A comparative analysis with operational tree loss monitoring using optical (30-m Landsat based Global Forest Watch (GFW), and microwave (L-band Synthetic Aperture Radar (SAR) JICA-JAXA (ALOS-2) Forest Early Warning System) revealed improved performance in mapping small landslides with current approach. These results emphasize the necessity of conducting local and large scale investigations of forest dynamics before and after landslides to meet environmental commitments at various levels. The landslide events will likely induce significant alterations in the forest's microclimate. Our research recommends an immediate action plan to restore affected sites, remove IAS, and encourage the planting of native vegetation for biodiversity conservation.