Phenological Evaluation in Ravine Forests through Remote Sensing and Topographic Analysis: Case of Los Nogales Nature Sanctuary, Metropolitan Region of Chile

Ravine forests play a key role in environmental regulation and biodiversity in fragmented landscapes. Continuous monitoring is essential to understand their dynamics and promote sustainable management. In this context, with the use of remote sensing techniques, it is possible to analyze spatial and temporal patterns of vegetation, integrating environmental factors such as topography and surface temperature. The objective of this study is to analyze the phenology of the species present in the ravine forests of the Los Nogales Nature Sanctuary, located in Lo Barnechea, Metropolitan Region of Chile, in an area of 4,743.2 hectares. Using Sentinel-2 satellite images (2019-2024) and the Alos Palsar Digital Elevation Model (12.5 m), we calculated the Normalized Difference Vegetation Index (NDVI), which evaluates plant vigor and biomass; the Topographic Position Index (TPI), which characterizes the relief; and the Diurnal Anisotropic Heat (DAH), which measures the interaction between solar radiation and surface temperature. The Generalized Additive Model (GAM) was used to evaluate the phenological time series. The results showed phenological stability in trees affected by climatic variations and greater sensitivity in shrubs and herbaceous plants. The topographic analysis indicated that trees predominate in elevated areas and herbaceous plants predominate in low areas with higher water retention. These findings highlight how vegetation responds to interactions between topography and environmental conditions in dynamic ecosystems, highlighting the potential of remote sensing for monitoring, analyzing, and understanding the forest ecosystem.