Investigating the Wind Flow Modulation of Tree Crown Morphology and Layout at Different Heights

Tree planting strategies play a critical role in improving local wind environments. This study investigates the effects of tree crown morphology and planting layout on wind regulation at two vertical levels, pedestrian height (1.5 m) and low-altitude canopy level (5 m), in Macau, a high-density subtropical city. Field microclimate measurements were combined with computational fluid dynamics (CFD) simulations to quantify the performance of three typical crown morphologies (ellipsoidal, cylindrical, and conical) under six planting configurations. Results reveal differentiated impacts across heights; under single trees and opposite tree plantings, ellipsoidal crowns produced the least wind reduction at 1.5 m but the strongest blockage at 5 m, while conical crowns caused substantial attenuation at 1.5 m yet allowed faster wind recovery at 5 m. Planting layouts further modulated these effects; a single-row of ellipsoidal crowns balanced pedestrian ventilation with upper-level wind protection, whereas opposite tree pair planting, enclosure planting and curved planting displayed contrasting performances depending on species morphology. The findings demonstrate that optimizing tree morphology and layout can precisely regulate ventilation and sheltering across height layers. This study provides scientific evidence for vegetation configuration in hot–humid high-density cities, supporting climate-responsive urban planning and design.