Dynamic changes in the sap flow of Haloxylon ammodendron in the Minqin desert region

Investigating the water consumption process of Haloxylon ammodendron is important for promoting the survival and growth of artificial sand-fixation forests in arid areas. In this paper, thermal diffusion (TDP) monitoring technology was used to obtain real-time sap flow data for H. ammodendron in the growth season in Minqin, and then dynamic changes in the sap flow were analyzed to provide important evidence for clarifying the water consumption during the growth process of H. ammodendron. The result was showed that the sap flow of H. ammodendron initially increased with age and then declined. The average sap flow velocity at 10, 15, and 20 years of age was 1.059, 1.460, and 0.570 cm³·(cm²·h)⁻¹, and the accumulative liquid flow quality in the growth season from May to October was 423.386, 1041.186, and 430.212 kg, respectively. The sap flow of H. ammodendron increased as the ground diameter thickened, and the maximum fluid flow period was delayed with the growth of H. ammodendron forests. The average sap flow velocity at the different stem levels was 0.276～2.132 cm³·(cm²·h)⁻¹, and the cumulative liquid flow quality in the growing season was 121.656～1722.810 kg. The sap flow of H. ammodendron in the large diameter class had an early start time, long duration, high peak value, which was observed between 07:00 and 08:00, and maximum flow velocity varied in a range of 2.767～5.536 cm³·(cm²·h)⁻¹; moreover, the daily maximum liquid flow rate was delayed by 1.5～4.0 h with increases in forest age. The sap flow changes of H. ammodendron in different age groups reflected the process of water consumption and its response to a drought-prone environment, while those at different diameters indicated that the growth of individual H. ammodendron trees has obvious competitive advantages. The analysis results can provide theoretical support for the estimation of ecological water use in H. ammodendron sand-fixation forests in desert areas.