2.2 Experimental design
In September 2021, the H. ammodendron plantation at the southeastern edge of the Badangirin Desert in the Alxa League was used as the study object. Using the method of spatial substitution of time, we sequentially selected the H. ammodendron plantation in 2016, 2010, 1999, and 1975 (5, 11, 22, and 46yrs, respectively) for the study, and these four vegetation construction sites were referred to as 5yrs, 11yrs, 22yrs, and 46yrs, respectively, with nearby moving sands (MS) as controls. Because all eras of the H. ammodendron plantation were in moving sands when planted and in the same location, soil texture, standing conditions, and meteorological conditions, satisfying the comparative study of pike soil samples from different eras. The information of each stand age sample site is shown in Table 1.
Tab. 1 The basic description of the studied sites