Variability of chromatic vegetation indices derived from digital repeat photography in the Biebrza Valley

This study presents an application of digital repeat photography to determine seasonal and interannual variability of chromatic vegetation indices of a wetland ecosystem in 2022–2024. The green chromatic coordinate (g cc ), along with red (r cc ) and blue (b cc ), revealed clear seasonal patterns, with the highest g cc values observed in summer and the lowest in winter. Despite similar annual trends, the timing and magnitude of vegetation greening differed significantly during those years. These differences closely followed variations in air temperature and growing degree day sums (GDDS), highlighting the strong influence of thermal conditions on vegetation phenology. The inverse seasonal response of rcc and winter-dominant b cc further reflected physiological changes and snow cover dynamics. While temperature emerged as the primary driver, findings from related studies suggest that other abiotic factors may also play a significant role. Further analysis is needed to fully understand the complex interactions shaping vegetation dynamics in this wetland environment.