Analysis of the Impact of Three Agricultural-Landscaping Composite Model Shelterbelt Structures on NDVI

Based on Sentinel-2A multispectral imagery, the spatial structure of shelterbelts was extracted using methods such as supervised classification, 3D-CNN, LOESS, and random forest. The correlation mechanism between the Normalized Difference Vegetation Index (NDVI) and structural parameters of shelterbelts was systematically analyzed, revealing the differential effects of shelterbelt structure on crops under different agroforestry patterns. The results indicate that under three agroforestry patterns, the protective effects of shelterbelts on maize, peanut, and soybean differ significantly. The effective protection distances are 273 , 263 , and 241 m, respectively, while the optimal protection distances are 140 , 80 , and 110 m, respectively. The key driving factors of NDVI vary among different crops: peanut is mainly influenced by shelterbelt density, soybean is dominated by shelterbelt width, and maize is most sensitive to shelterbelt length, with importance scores of 24.81, 25.89, and 24.73, respectively. The optimal shelterbelt configurations for different crops exhibit both convergence and divergence. All three crops show highly consistent requirements for shelterbelt orientation, concentrated between 30°～45° and 135°～145°. For other structural parameters, the three agroforestry patterns show differentiated demands. Peanut and soybean have similar preferences in terms of length, density, and height, with optimal reference values of 2000–2500 m, 0.25～0.35, and 17～19 m, respectively. Maize, however, is only similar to peanut in width (both within 10～15 m) and displays uniqueness in all other aspects.