Fertile islands under Artemisia ordosica in inland dunes of northern China: Effects of habitats and plant developmental stages

Plants may induce small-scale heterogeneity in soil nutrients, forming fertile islands. However, this process may depend on plant developmental stages and habitat conditions. We address whether fertile islands are formed under semi-shrubs of Artemisia ordosica in Ordos Plateau, a semiarid region in northern China, and how they are affected by developmental stages and habitat conditions. We selected young, mature and senescent individuals of A. ordosica from three habitats, i.e. the fixed dune, leeward and windward slopes of the mobile dune. At the location of each individual, we took soil samples beneath, at the edge of and outside canopies from 0–10 to 10–20 cm depth, and measured total organic carbon (TOC) and total nitrogen (TN). Soil TOC and TN were highest beneath and lowest outside the canopies. The differences in TOC and TN between soil beneath and outside the canopies were larger in the fixed than in the mobile dune, at the surface than at the deeper layer, and under the mature and senescent than under the young individuals. We conclude that fertile islands were formed under A. ordosica semi-shrubs, and that they are more strongly developed in fixed than in mobile dunes, in the surface soils than in the deeper soils, and under the mature and senescent individuals than under the young individuals.