Pattern Of Microbiotic Soil Crust And Its Influential Factors Under Artemisia Ordosica Shrubs In Mu Us Sandy Land

Microbiotic soil crust is developed broadly in arid and semi-arid areas. It has important effects on improving physical and chemical properties of soil, as well as maintaining the stability of the community. In this paper, we investigated the distribution of microbiotic soil crust under Artemisia ordosica shurbs in the Mu Us Sandland, and analyzed the patterns of microbiotic soil crust and its influential factors. The main research findings are as follows:(1)The distribution of the microbiotic soil crust like zonal around the roots of under the canopy of Artemisia ordosica, the thickness of microbiotic soil crust is uneven, changing regularity with the distance from the roots and different directions. The maximum thickness, 0.86cm, occurs at the position of 20 cm from the main roots. Outward from the position, the thickness of microbiotic soil crust reduced in ring by a rate of 0.07cm every 10 cm. The radius of microbiotic soil crust is longer southeastward than that in the other three directions, while it is shorter than others northwestward. Microbiotic soil crust is thickest southeastward and is thinnest northwestward.(2) The organic matter, total nitrogen and grain size changing regularity with the distance from the roots under the canopy of Artemisia ordosica.The percentage of coarse sand decreasing with increases of the distance from the roots, while coarse silt and fine sand increasing with increases of the distance from the roots. The percentage of organic matter and total nitrogen in the microbiotic soil crust decresing with destance far from the roots in general . The distribution of microbiotic soil crust could promote the development of surface soil and increases nutrients in soil.(3) The regularity of the influential factors distribution under the canopy of Artemisia ordosica is obviously. North wind is the main wind in the study area (the percentage rate of northwest, due north and northeast wind is 0.51 throughout the year). Affected by the main wind, the type of Artemisia ordosica appears different in directions, the northwest branch of Artemisia ordosica is shorter, less density, when southeast longer, more density. The length, density of the other two directions is between the former two. The litterfall under the Artemisia ordosica shurbs mainly came from the plant of Artemisia ordosica. The distribution of litterfall under the plant is determined by the main wind and the type of the Artemisia ordosica, which is changing with the distance and the directions. All of the organic matter, total nitrogen and grain size have some correlation with the distance from the roots under the canopy of Artemisia ordosica.(4) The pattern of the microbiotic soil crust under the canopy of Artemisia ordosica is affected by multiple factors. Affected by the main wind, the type of Artemisia ordosica appears different in directions, which cause the heterogeneith of wind, light, rain, atmospheric dust and litterfall under the canopy of Artemisia ordosica. The cover of litterfall and the vegetation reduced the light under the Artemisia ordosica shrubs, the temperature and humidity of surface soil is keeped suitable for microorganism activity; also the decomposition of litterfall increased the soil organic matter, which provided the necessary nutrient for the development of microbiotic soil crusts. The pattern of litterfall result in differences of soil properties. The development of microbiotic soil crust could increase fine particles of surface soil and increase soil nutrients, at the some time, the increase of soil nutrients are beneficial for the development of microbiotic soil crust, beneficial to both.