Response of three dominant shrubs to soil water and groundwater along the oasis-desert ecotone in Northwest China

The ecotone from oasis to desert is an important area for combating sandy desertification. Three dominant desert shrubs (Nitraria tangutorum, Calligonuum mongolicum, Haloxylon ammodendrori) were selected in Minqin Oasis, Northwest China, to determine the groundwater level; soil water potential; and change of the three shrubs in density, coverage, and biomass along the natural and seminatural oasis-desert ecotone (ODE), respectively. The results indicated that traits of desert plant interaction with the topsoil water and groundwater depth along the ODE play an important role in generating complex desert vegetation spatial dynamics. Some natural desert plant species with shallow root systems will distribute themselves according to distribution of topsoil water. Thus, the distribution of Nitraria tangutorum had a decreasing trend in distribution along ODE. Calligonuum mongolicum occurs in different trends in natural and seminatural ODE due to utilizing groundwater as well as topsoil water. Some plant species with deep roots, such as Haloxylon ammodendron, will show more degradation near oases and will exhibit an ascending trend along ODE. Therefore, it is of primary importance to protect the integrity of groundwater depth in order to protect the stability of the oasis-desert ecotones. The text was submitted by the authors in English.