Wind and sand control in composite shelterbelts combining Cyperus esculentus with trees and shrubs: Evidence from wind tunnel and field studies

Cyperus esculentus ( C . esculentus ), a desert-adapted plant species with both ecological and economic value, has been widely cultivated in northern China's sandy regions. However, limited studies have investigated the performance of composite shelterbelts that integrate C . esculentus . This study systematically evaluated five shelterbelt models— Populus euphratica ( P . euphratica ), P . euphratica–C . esculentus composite, P . euphratica– nylon net –C . esculentus composite, Tamarix chinensis ( T . chinensis ), and T . chinensis–C . esculentus composite—using wind tunnel experiments and field observations. Sediment flux was measured at a normalized downwind distance ( x / h ) of 5, where x refers to the distance from the front edge (upwind side) of the shelterbelt for upwind measurements, and the distance from the rear edge (downwind side) for downwind measurements, and h represents the canopy height. Wind velocity was measured at x / h of –2, –1, 1, 2, 3, 5, and 7, and sand flux was measured at x / h =5, under initial wind velocities of 8.0 and 12.0 m/s. The results indicated that the P . euphratica– nylon net– C . esculentus composite was the most effective in reducing wind velocity, followed by the P . euphratica – C . esculentus composite. In contrast, the P . euphratica and T . chinensis exhibited relatively weaker wind reduction capabilities. Regarding sand flux, under moderate wind velocity (8.0 m/s), both the P . euphratica – C . esculentus composite and P . euphratica –nylon net– C . esculentus composite demonstrated the lowest sand flux values. However, under high wind velocity (12.0 m/s), the P . euphratica –nylon net– C . esculentus composite significantly outperformed the other shelterbelt models in sand retention, highlighting its superior windbreak and sand fixation efficacy. Field observations further validated the windbreak and sand fixation effects of C . esculentus . Comparisons between the bare sand plot and C . esculentus plot within protective forests demonstrated that planting C. esculentus can provide substantial ecological benefits in windbreak and sand-fixation. These findings, reinforced by field observations, strengthen the wind tunnel experiment results and highlight the critical role of C . esculentus in enhancing the performance of composite shelterbelts for desert ecological restoration .