Study On Spatial Pattern Of Artemisia Ordosica Communities In Different Habitats In Mu Us Sandy Land

Artemisia ordosica is one of the most excellent sand binding plants in arid-semiarid region of northern China. It can be found in most areas of Mu Us Sandy Land. In order to promote the application of this plant material in sand fixation as well as Chinese shifting sand treatment technology, artificial mixture Artemisia ordosica community and natural community were selected in Mu Us Sandy Land, Ningxia province. Population composition, spatial point pattern, differentiation between patches and patch gaps, heterogeneity and the relationship between Artemisia ordosica and biological crust were studied.First, structure features of both shrub layer and herb layer had been made comparisons under typical habitat including fixed sandy land, half fixed sand, shifting sandy land, sunny slope and shady slope. The results show that in half fixed sand, Artemisia ordosica on shady slope achieved higher survival rate than that on sunny slope. It is the moisture content instead of sunlight that mainly influences the growing condition of Artemisia ordosica in arid-semiarid region. Survival rate of Artemisia ordosica in shifting sandy land is higher than that of fixed sandy land which can reflect the fact that both shifting and sandy half fixed sand have better moisture condition than fixed sand. Regions of Mongolia and north china have the most kinds of Artemisia ordosica community. Most life form of Artemisia ordosica community is hemicryptophyta while no cryptophytes. Based on the relation between plants and moisture, water ecotype of xerophyte and mesoxerophyte take the dorminate position. Psammophyte is the main constructive species and dominant species of Artemisia ordosica community.Size and structure of both artincial mixture and natural Artemisia ordosica community have been made comparisons under four different habitat conditions. The results show that percentage of young Artemisia ordosica appears in artincial mixture areas which also shows conspicuous grow trend. Natural Artemisia ordosica community has more evenly age distribution and larger amount as well as much more integrated structure compared with artificial mixture area. Artificial mixture Artemisia ordosica has to face many problems such as hard to refresh and serious aging. Grazing can improve the condition of Artificial mixture Artemisia ordosica.Using point pattern analysis to study the spatial pattern of the population of the four habitats in mixed and natural Artemisia ordosica to find the close relationship between the factors of spatial scale, plant size, habitat conditions and human disturbance to the spatial pattern of the population of Artemisia ordosica. Artemisia ordosica and hedysarummaxim have tended to cluster distribution In general which are in the relationship of competitive exclusion. Even after the death of Artemisia ordosica, hedysarummaxim can't live on the place where Artemisia ordosica have survived. Both of them can be together temporarily when they are young. The bigger the difference between Artemisia ordosica age class, the more competitive to each other will they are, which are one of the main reasons of Artemisia ordosica population patchiness.Using geo-statistics and semi-variance analysis to study the spatial heterogeneity of Artemisia ordosica population shows the result that the spatial autocorrelation and spatial heterogeneity of natural Artemisia ordosica population are stronger than the mixed ones, among which the differentiation of plaque and plaque clearance are obvious. Compare to different artificial habitats in mixed Artemisia ordosica communities, Grazing and other human disturbance led to the Artemisia ordosica population spatial heterogeneity weakened, the distribution in the form of patchiness are broken, which has played a catalytic role to the update of Artemisia ordosica seedlings. Excluding the impact of artificial interference, as the increase of the soil crust and the decrease of soil water, artificial mixed Artemisia ordosica can restrain the process of Artemisia ordosica population patchiness, which reduce the Artemisia ordosica spatial heterogeneity and spatial autocorrelation relationship.The result of this research has certain theory significance to know about succession of Artemisia ordosica, and has certain directive function to quick sand manage technology to improve the Mu Us Sandland in arid, semi-arid region. Artemisia ordosica population can easily form the cluster distribution and plaque differentiation is obvious, so we should Plant Artemisia ordosica into the appropriate area and density plaque and leave the appropriate gap between plaques rather than transplante them in uniform distribution of low-density to the flow of sand, which can enhance the survival rate of the transplanted ones, using Artemisia ordosica good natural regeneration capacity to promote plaque clearance of vegetation recovery process. In addition, appropriate jamming in artificial planting and closed fencing region can promote the update of Artemisia ordosica.