Title: Seasonal Assessment of Perennial Tree Stand Conditions Using Landsat-Derived NDVI and NDMI: Evidence from Quva District, Uzbekistan
Authors: Sherzodbek Yokubov, and Marjonakhon Zokirjonova
Volume: 10
Issue: 7
Pages: 108-115
Publication Date: 2026/07/28
Abstract:
Perennial tree stands in irrigated agricultural landscapes are affected by seasonal vegetation development, water availability and stand structure. This study evaluates the seasonal condition of perennial tree stands in Quva district, Fergana Region, Uzbekistan, using Landsat 8 OLI/TIRS Level-2 Surface Reflectance data and the Normalized Difference Vegetation Index (NDVI) and Normalized Difference Moisture Index (NDMI). Four observation periods in 2025 were analyzed: April, June, August and October. The workflow included QA/cloud screening, index calculation, clipping to the district boundary and zonal statistics for 32 cadastral contours of perennial tree stands. Field-inventory data for 2025 were used as contextual reference information. The weighted mean NDVI was 0.2090 in April, 0.2069 in June, 0.2206 in August and 0.1611 in October. The weighted mean NDMI was 0.0851, 0.0631, 0.0829 and 0.0442 for the same periods. August showed the highest NDVI and relatively high NDMI, while October showed the lowest values of both indices, reflecting autumn vegetation decline and reduced moisture-related spectral response. The correlation between contour-level NDVI and NDMI remained very high across all months (r = 0.984-0.992), indicating that vegetation activity and moisture condition were closely related in the investigated perennial tree stands. The results demonstrate that seasonal NDVI-NDMI analysis is useful for identifying periods of vegetation weakening and moisture stress, supporting field inspection planning, cadastral clarification and land-resource monitoring in irrigated agricultural areas.