Effectiveness of wind and sand stabilization by artificial Haloxylon ammodendron forests of different ages in Turpan City and its relationship with biomass
[Objective] The aims of this study were to explore the wind and sand flow prevention and stabilization benefits of artificial Haloxylon ammodendron forests with different planting years, rapidly evaluate the wind and sand flow prevention and stabilization benefits, and define the lower limit of the biomass-anti-sand flow prevention and stabilization benefits to provide scientific basis for the restoration and reconstruction of desert vegetation. [Methods] Artificial H. ammodendron forests of varying planting ages in desertified areas of Turpan City, Xijiang Wei Autonomous Region, were selected as the study subjects. Field surveys, observations, and laboratory analyses were conducted to monitor windbreak and sand fixation benefit indicators. The relationships between these indicators and the changes in biomass were compared. [Results] ① The windbreak efficiency, surface roughness, surface erosion-deposition volume, and sand-blocking efficiency of artificial Haloxylon ammodendron forests significantly improved (p < 0.05) with increasing planting age. ② The wind speed profile in the region changed with the growth of artificial H. ammodendron forests. The wind speed profile of the primary desert showed type ‘L’ change characteristics, the wind speed profile of the 2 and 4-year-old artificial H. ammodendron forests showed type ‘I’ change characteristics. The wind speed contours of 6, 8, and 10-year-old planted H. ammodendron forests showed the opposite of type ‘J’ changes. ③ The sand transport flux of the planted H. ammodendron forest showed a decreasing trend with an increase in the establishment period and also showed a decreasing trend with an increase in height. ④ The biomass-windbreak and sand fixation efficiency index model was constructed based on five age-variant H. ammodendron forests, in which the best function models between the standing biomass index and the relationship between windbreak efficiency, surface erosion, surface roughness, sand transport flux, and sand blocking efficiency was the power function, the idempotent function, quadratic function, exponential function, and the logistic function models with R2 values of 0.651, 0.962, 0.790, 0.804, and 0.925, respectively. ⑤ The standing biomass index of artificial H. ammodendron forests must reach a minimum threshold of 4.94 kg/m² to achieve effective windbreaks and sand fixation benefits. [Conclusion] Artificial H. ammodendron forests achieved stable windbreak and sand fixation benefits 4 years of planting. These benefits could be estimated using the relevant models. The forests could stably deliver windbreak and sand-fixation effects when the standing biomass index was ≥4.94 kg/m².