Influence of Stipa spp. on near-surface aeolian process: A wind tunnel simulation

With global climate change, alpine meadows face an intensified risk of desertification, and Stipa spp. are the dominant constructive species in these ecosystems. Understanding the influence of Stipa spp. on aeolian processes can clarify the mechanisms of alpine meadow aeolian desertification. It also provides guidance for desertification control and ecological restoration in alpine meadows. In this study, wind tunnel experiments were conducted under conditions representative of the alpine meadow environment of the Tuotuo River region on the Qinghai-Tibet Plateau. The effects of Stipa spp. on wind characteristics, sand erosion and deposition, and transported sand properties were systematically investigated, revealing their key role in near-surface aeolian processes. The results showed that Stipa spp. (20-30 cm tall) effectively reduced wind speed at a height of 12 cm. At 0.3 cm, the mean wind speed reduction rate reached 17.49%. At heights above 12 cm, airflow was slightly accelerated. The presence of Stipa spp. also significantly increased roughness and friction velocity. Furthermore, Stipa spp. mainly affected the erosion and deposition stages of sand transport, and sand deposition was observed under low wind speeds. At 12 m/s, sand erosion and deposition rates over the Stipa spp. surface were 46.7-fold and 455.6-fold lower, respectively, than those on the sand surface. However, the structure of wind-sand flow remained largely unchanged. Grain-size analysis showed that the mean grain size of transported sand over the Stipa spp. surface was 3.22 Φ at 16 m/s, compared with 2.38 Φ over the sand surface. This indicates that Stipa spp. preferentially retain coarse particles, while finer particles are lost. Such selective retention may contribute to nutrient loss, potentially exacerbating desertification. Overall, Stipa spp. influenced near-surface aeolian processes by modifying airflow, controlling sand erosion and deposition, and redistributing transported sand.