Influencing mechanisms of several shrubs on soil chemical properties in semiarid Horqin Sandy Land, China

摘要

Horqin Sandy Land is one of the serious desertification areas in the semiarid zone of north China. Shrubs are the dominant plant species in this region and they play an important role in the wind erosion-prone fragile ecosystem. This study deals with the differences of some chemical properties in the soils under shrub canopies and from adjacent open spaces and analyses their characteristics in the shrub rhizospheric soils and bulk soils. The results showed that: (1) the concentrations of organic C, total N, and total P, and the value of electrolytic conductivity (EC) in the soils under the canopy of shrubs increased by 56%, 51%, 37%, and 51%, respectively, compared with those of the soils in open spaces, but there was no significant difference in pH between the soils under shrub canopies and open spaces; (2) shrub rhizosphere soils exhibited significantly higher contents of organic C, total N, and values of EC as well as a lower value of pH compared to the bulk soils, but there was no significant difference in total P between rhizosphere and bulk soils; (3) there were close relationships between the properties in soils under shrub canopies and the rhizosphere soils, indicating that the development of "fertile islands" are favorable to root growth and induce greater amount of rhizodeposition, and vice versa; and (4) soils under Artemisia frigida and Caraganda microphylla canopies and rhizospheres had significantly higher organic C and total N contents than those of Artemisia halodendron and Salix gordejevii. The results suggested that shrubs were of vital importance for the sequestration and accumulation of nutrients and maintenance of soil fertility in the Horqin Sandy Land ecosystem.