Spatial heterogeneity and diversity of vegetation at the landscape level in Inner Mongolia, China, with special reference to water resources

Inner Mongolia, China, was divided into five different areas (landscapes) based on the annual overland flow of water (AOF): <2, 2–5, 5–10, 10–50, and >50 mm. Two maps of plant communities with a 1-cm² grid and the AOF were overlaid (scale: 1 cm = 15 km). Each plant community that occurred in each 1 cm × 1 cm cell (S-cell) was recorded, and the number of occurrences of each community type was counted for groups of four neighboring S-cells (L-cell). These data were statistically analyzed using the power law for each of the five landscapes. The per L-cell community richness and diversity for dry (AOF < 2 mm) and subhumid (AOF > 50 mm) landscapes were low compared to those of the three mesic landscapes (2–50 mm AOF). Community spatial heterogeneity was low in mesic landscapes. The dry and subhumid landscapes consisted of a small number of community types and exhibited monotonous spatial change, while the mesic landscapes consisted of rich plant communities that were spatially intermingled because natural conditions, such as climatic and edaphic conditions, in the landscapes are complex and divided into small areas, and, furthermore, historical anthropogenic activities such as livestock grazing, especially in landscapes with AOFs of 2–50 mm, have divided the landscape into small fragments.