Assessment of Phenological Dynamics in Tropical Deciduous Forests

Phenological monitoring of tropical deciduous forests has become increasingly critical in understanding ecosystem responses to global environmental change. Since there is a dearth of in situ phenological monitoring in the Gir forest ecosystem, a tropical dry deciduous forest in India, our study offers vital baseline data for comprehending vegetation dynamics in this area. This study presents a detailed analysis of the canopy phenology of Gir Forest National Park, India, using high-temporal resolution PhenoCam imagery from October 2022 to May 2024. We employed a systematic approach to extract and analyze green chromatic coordinates (GCCs) from defined regions of interest (ROIs) within PhenoCam imagery. Through pairwise correlation analysis between color channels and a detailed examination of GCC patterns, we quantified seasonal transitions in leaf phenology, providing insights into the timing and duration of growing seasons. This methodology enables precise quantification of phenological metrics, including the timing of leaf emergence, peak greenness, and senescence, which are essential for understanding vegetation responses to environmental drivers. The median values in the GCC demonstrated the most stable seasonal pattern, with values ranging from 0.332 to 0.368. The analysis revealed asymmetric phenological transitions, with a prolonged green-up period (164 days) and a relatively shorter senescence phase (39 days). Our results create an effective structure for tracking the phenology of tropical forests and offer valuable reference data for examining how environmental factors and tree phenology interact in the context of climate change. This research contributes to filling a critical knowledge gap in understanding phenological variations and ecosystem functions in the Gir forest, offering insights that are particularly relevant as global environmental changes continue to have impact on forest ecosystems.