Scale-dependent spatial heterogeneity of vegetation in Mu Us sandy land, a semi-arid area of China

To examine spatial scale-dependent variation in the vegetation in Mu Us sandy land, in the semi-arid area of NW China, two transects (5 km in length, meeting at right angle) were set, and two vegetation attributes (quantitative descriptors), vegetation cover and number of plant species, were investigated. The data were analyzed combining geostatistics and fractal geometry. Nested spatial structures were revealed for both vegetation attributes, indicating the existence of multi-scale variations. The large fractal dimensions (>1.70) commonly found in the vegetation suggest the dominance of small-scale variations. Shifting in fractal dimensions was detected, implying scale-dependent spatial variation of the vegetation, as well as its hierarchical organization. Significant differences in spatial variation of the vegetation attributes between the different directions were also found, suggesting a zonal anisotropy of geomorphologic processes.