Does memory of hydrological processes and atmospheric dryness influence forest fire intensity: A case study in the western Himalayas

Forest fires in the Western Himalayas are characterised by high-intensity energy releases, resulting in influencing forest functionality. In contrast, fire management remains largely reactive due to limited understanding about the climatic and ecological drivers of forest fires in the region. The current study was attempted to identify the relationships between climatic and ecological drivers with fire intensity by integrating a 13-year (2012–2024) spatially thinned fire dataset with multi-seasonal hydroclimatic, vegetation, and terrain variables across different Himalayan forests in Himachal Pradesh, India. These variables were modelled for fire radiative power using structural equation modelling (SEM) and random forest bench marking. The findings indicate a significant hydrological memory effect, whereby antecedent winter precipitation (AWP) influenced pre-monsoon fuel moisture and was indirectly associated with fire intensity, whereas spring rainfall had a non-significant impact. Vapour pressure deficit (VPD) exhibited the strongest direct association with fire intensity (β = 0.15), while multi-group SEM revealed ecosystem-specific responses. AWP showed a significant positive effect on vegetation moisture across all forest ecosystems, whereas VPD showed a significant negative effect. In dry deciduous forests, vegetation moisture (β = −0.185) and distance to housing (β = −0.140) also significantly affected fire intensity. Gradient hydroclimatic perturbation analysis (±10% and ±20%) indicated that fire intensity was more sensitive to changes in VPD and vegetation moisture than to changes in AWP. Overall, AWP and VPD were associated with vegetation moisture and fire intensity, providing a mechanistic understanding of the hydroclimatic pathways across Himalayan Forest ecosystems.