Rhombomys Opimus Contribution to the "Fertile Island" Effect of Tamarisk Mounds in Junggar Basin

Fertile islands are created and maintained by a combination of physical and biologically mediated processes. Previous studies indicated a number of biotic factors are related to the development of fertile islands. Plants have been shown to be very important in the formation of fertile islands, and recent research indicated that the activities of burrowing animals have a significant influence on the physiochemical properties of soil that can promote the development of fertile islands. But the study about the role of plants and animals in the creation process of fertile islands is very limited.

The oasis-desert ecotone is an interactive area between desert and oasis ecosystems that plays an important role in ensuring ecological security and maintaining oasis internal stabilization. Tamarisk (Tamarix spp.) is the dominant species in the ecotone areas of the Junggar Basin in western China. Recent studies showed that the water and other resources [N, P, and soil organic matter under the canopy of tamarisk are significantly higher than that found in interspaces.

Because of the litter accumulation and dust sediment, “tamarisk mounds” are formed around the tamarisk plant and constitute a special desert bio-landscape in arid areas. The tamarisk mounds are important habitat for the great gerbil (Rhombomys opimus), which is widely distributed in central Asia. Great gerbils can produce elaborate multi-chambered burrow systems in the mounds, and hoard food in storage chambers, which can reach up to 100 kg of stored food. Burrow systems and food-hoarding behavior may increase the soil nutrients by accumulating plant material from food and nests.

To study the influence of great gerbils on soil nutrient dynamics in tamarisk mounds, Dr. XU Wenxuan et al. chose the tamarisk (Tamarix spp.) and the great gerbil (Rhombomys opimus) as the study objectives. The results indicated that fertile islands exist in tamarisk mounds without burrows of the great gerbil. However, the great gerbil’s burrowing activities promoted the fertile island effect in tamarisk mounds: soil nutrients under shrubs with great gerbil activity were significantly higher than inter-mound areas in both surface soil and deep soil from 15 to 50 cm. Available nitrogen in mounds with rodent burrows was over twice as high as in tamarisk mounds without burrows at the same depth. The findings showed that great gerbil’s burrowing activities could promote the concentration of soil nutrients in the tamarisk mounds.

The result has been published on Ecological Research, 2012, 27: 775-781. The paper can be downloaded from http://www.springerlink.com/content/x4196l750qp241p8/.