Study on temporal stability of soil moisture in Haloxylon ammodendron plantations of different ages in the Minqin desert area

Abstract

[Objective] The temporal stability of soil moisture in Haloxylon ammodendron plantations in desert regions was elucidated to provide a foundation for optimizing soil moisture monitoring and prediction. [Methods] Field-observed soil moisture content data from the 2023 growing season were analyzed using classical statistical and temporal stability analysis method. The spatiotemporal variability and temporal stability of soil moisture were investigated at depths of 0~400 cm in Haloxylon ammodendron plantations aged 5 to 25 years. Spearman rank correlation coefficients and relative differences were calculated to assess the temporal stability of soil moisture. [Results] Soil moisture content in the surface layer(0~100 cm) remained relatively stable across stand ages, maintaining high levels between 6% and 9%. In contrast, soil moisture content in the 100~400 cm layer significantly decreased with increasing stand age, exhibiting fluctuations ranging from 2% to 9%. Deeper soil layers showed greater variability than shallower layers. The spatial variability of soil moisture content increased with soil depth.Plantations younger than 10 years demonstrated high temporal stability of soil moisture(Spearman rank correlation coefficient >0. 8). Conversely, the temporal stability of soil moisture in deeper layers of older plantations(15 years, 20 years, and 25 years)was significantly reduced. [Conclusion] The dynamics of soil moisture in Haloxylon ammodendron plantations in desert regions are jointly influenced by stand age and soil depth. Overall, soil moisture content decreased with increasing stand age, primarily due to scarce precipitation, intense evaporation, and substantial water consumption through transpiration in the study area.Appropriate water management measures should be implemented in older plantations to ensure sustainable soil moisture use. New insights into the impact of artificial vegetation on soil moisture balance and ecosystem health are provided.

Keywords

soil water content / spatio-temporal change / Haloxylon ammodendron / temporal stability / Minqin desert / influencing factors