Background In arid and semi-arid regions, soil moistureis the core of ecosystem in sandy land, driving material circulation and energy flow in the soil-plant-atmosphere continuum (SPAC) system. However, Mu Us sandy land was located in arid and semi-arid areas, and the inter-annual variability of precipitation is large. There have been few studies on the interaction relationship between between Amygdalus pedunculate and soil moisture, especially the analysis of the temporal and spatial variability and temporal stability of soil moisture in this area after the large-scale planting of A. pedunculate is still unclear.

Methods From March 2018 to October 2019, the soil moisture contentsof 30 water points in the 0-300 cm section of the A. pedunculate woodland of the fixed dune on the southeast edge of Mu Ussandy land was continuously measured with a CNC503DR neutron. The spatiotemporal variability and temporal stabilities of soil moisture at different depths were studied using classical statistics and temporal stability analysis, and the data processing tool adopted SPSS and Excel 2016.

Results 1) The soil layers showed a medium variance during the period of measurement. The soil moisture content of 0-50 cm was low and the temporal variability was strong. The soil moisture content in 200-300 cm was higher and the spatial variability was stronger, which was significantly different from other layers.2) Spearman rank correlation coefficient of soil moisture content (0-300 cm) was extremely significant. Most rank correlation coefficient of soil moisture content in2018was more than 0.6 and showed a certain temporal stability. 3) The mean relative difference ranges of 0-50, 50-100, 100-200 and 200-300 cm were respectively -23.69%-32.47%, -28.4%-42.14%, -25.65%-74.61% and -72.02%-147.03%, andmean standard deviation ofits relative differences were 14.12%, 9.80%, 21.40%, 9.52%, respectively. Based on the cumulative probability and relative difference analysis, the temporal stability of soil moisture content increasedwith the increase of soil depth, andthe temporal stability of soil moisture content 200-300 cm was stronger; the R² of mean soil moisture content at representative measuring points of each soil layer in the study area was 0.67 and 0.90. 4)The water balance analysis showed that the maximum evapotranspiration water consumption of the shrub community on the windward slope of the study area appeared from early July to mid-August. During the monitoring period, the soil moisture conservation of the shrub community of A. pedunculate was greater than its consumption, and the precipitationmet the normal growth of the shrub community of A. pedunculate.

Conculsions During the monitoring period, the soil moisture content in the A. pedunculate woodland area was in positive balance. The temporal stability of soil moisture content at each measuring point increased with the increase of soil depth, and the representative measuring points may accurately predict the average soil moisture content at each measuring point in the range of 0~300 cm.