Abstract: In this paper, we take the forest shelterbelt system around Jilantai Salt Lake as the research object, to assess its shelter effect after 35 years running. During a strong dust event in May of 2017, the sand transport above the different underlying surfaces (0-0.50 m) around the shelterbelt system were monitored. We reevaluated the protective effectiveness of the shelterbelt system. The results indicated that the total sediment transport fluxes reduced as the following sequence:active longitudinal dune > Nitraria Tangutorum vegetated dune > salt lake > lakeshore > shelterbelts. With the increasing of the forest coverage, the surface wind speed decreased more obviously, the total amount of sediment transport flux in the shelterbelt was only 5.96% of the active longitudinal dune. The now days' decrease proportion of sediment transport in the forest belt to the active longitudinal dune was 4 times of that 35 years' ago. Over 84.70% of the sediment transport in the shelter system was within 0.3 meters above the ground surface, and 7.36%-87.34% was concentrated within 0.1 meter. Based on the results of the sand flow eigenvalue, the sand flow occurred twice conversions between wind erosion and deposition during the shelterbelt system, the active longitudinal dune showed erosion, the Nitraria Tangutorum vegetated dune, shelter forest and lakeshore showed deposition, while the salt lake turned to be erosion again. In 1986, the amount of sand transported in the shelterbelt was 22.22% of the active longitudinal dune. While in 2017, it decreased to 4.54%. After 35 years running, the sand-trapping efficiency of the shelterbelt system around Jilantai Salt Lake was getting more and more effective.

Key words: sand transport structure, shelterbelt system, underlying surface, Jilantai Salt Lake