ANALYSIS OF ALEPPO PINE VITALITY AT CHETTABA USING NDVI

Abstract

The study was carried out in the Chettaba state forest, located in the Constantine region (north-east Algeria), to analyze the dendrometry structure and ecological dynamics of Aleppo pine (Pinus halepensis Mill.) stands in a semiarid Mediterranean context. Three representative stations were selected to characterize structural and physiological variations in the stands, based on field measurements and spectral data from the Normalized Difference Vegetation Index (NDVI) collected in 2024. The dendrometry results show a density of 312-725 stems/ha and a basal area of 22.46-41.32 m²/ha. This progression reflects the accumulation of woody biomass and structural differentiation, with differentiation increasing with increasing competition. Low-density stands are distinguished by higher average diameters (D = 29.85 cm), reflecting mature, well-balanced individuals, while denser stands feature more slender stems and marked competition for light. The height/diameter (H/D) ratio, ranging from 31 to 39, indicates satisfactory mechanical stability and good structural balance. NDVI analysis reveals apparent seasonal variability, with a peak in vegetative vigor in June (mean NDVI = 0.248), followed by a decline in August and October (NDVI ≈ 0.19), linked to summer water stress and leaf senescence. Statistical tests (Friedman and Nemenyi) confirm highly significant differences between periods of active growth and phases of vegetative rest. The convergence of dendrometry and spectral analyses reveals a positive correlation between stand vigor and NDVI, underscoring that medium-density stands (around 400 stems/ha) exhibit the highest productivity and ecological resilience. These results demonstrate the relevance of integrating field measurements and satellite indicators for monitoring forest vitality and the sustainable management of semi-arid Mediterranean ecosystems