Spatial heterogeneity of plant height-crown width of sand-binding shrubs in semi-fixed dunes along the southern edge of the Gurbantünggüt Desert

In this study, four dominant sand-binding shrub populations in the semi-fixed dunes of the Gurbantünggüt Desert were used as research objects at the stand-scale. Isotropic and anisotropic spatial variation characteristics of plant height and crown width (east-west and north-south) were analyzed using variation function. Results showed that: (1) The plant height and crown width size of the four sand-fixing shrub populations followed the order Haloxylon persicum Bunge ex Boiss. et Buhse > Calligonum leucocladum (Schrenk) Bge. > Artemisia ordosica Krasch. > Ephedra distachya L.. Significant differences in plant height and crown width were observed among the four populations, except for between E. distachya and A. ordosica. (2) The variation function values of plant height and crown width of the four populations exhibited the same trend with increasing spacing distance, with a certain fluctuation within the local range. (3) Plant height and crown width of most populations showed strong spatial autocorrelation patterns. Spatial variation in crown width of the C. leucocladum population and plant height of the E. distachya population were co-determined by random and structural factors. The spatial variation patterns of plant height and crown width of the other populations were mainly due to structural factors. (4) The spatial patterns of plant height and crown width of the four populations were relatively simple, with spatial heterogeneity shown in different directions.