Windbreak and sand-fixing effects of typical nebkhas in the Yabrai Mountain aeolian corridorOA

Nebkhas are important aeolian landforms in arid regions and have notable windbreak and sand-fixing functions.However,the effects of shrub type and developmental stage on nebkha performance in high-wind energy regions remain insufficiently understood.This study quantified the windbreak and sand-fixing effects of three typical nebkha types(i.e.,nebkhas formed by Reaumuria soongorica,Caragana tibetica,and Nitraria tangutorum)at different developmental stages(i.e.,initial,developing,stable,and activated stages)in the Yabrai Mountain aeolian corridor,a high-wind energy region in China.Field sampling was carried out in three subregions along the prevailing wind direction(upwind,central sand-transport,and downwind)in March and November 2025.Particle-size analysis was conducted to characterize the differentiation of surface aeolian sediments,and field measurements combined with numerical simulations were used to analyze wind-speed profiles,windbreak efficiency,and airflow structure.The results showed that surface sediments on the windward slope and mound crest were dominated by clay and silt,whereas higher sand fractions occurred on the leeward and lateral slopes.The mean particle size followed the order:N.tangutorum(2.27Φ)<C.tibetica(2.30Φ)<R.soongorica(2.37Φ).Windbreak and sand-fixing effects ranked as stable stage>activated stage>developing stage>initial stage,with N.tangutorum nebkhas showing the strongest performance.When airflow passed over the nebkhas,wind speed increased above the canopy and along the lateral slopes;at the same time,a pronounced leeward deceleration zone formed within normalized horizontal distance(x/L)of 0–6 and relative height(z/H)of 0.0–0.5,where x is the horizontal distance,z is the vertical height,and L and H denote the shrub canopy major axis and shrub canopy height,respectively.Wind speed increased with z/H and x/L in the leeward direction and approached the reference wind speed over bare ground at z/H>1.2.Similar airflow patterns were observed among nebkha types.Prioritising N.tangutorum,combined with C.tibetica,and maintaining suitable developmental stages can enhance windbreak and sand-fixing performance in high-wind energy regions.These findings provide a scientific reference for constructing stable and efficient ecological protection systems in extreme wind environments,and support sand-control planning and vegetation configuration in arid and semi-arid areas.