Point Pattern Of Artemisia Ordosica And The Impact To Soil Crust Thickness In MuUs Sandy Land

Applying Ripley’s K function bivariate point pattern analysis method, three typical sample plots were selected from fixed sandy land, semi-fixed sandy land and Artemisia ordosica land to find:1) Point patterns of Artemisia ordosica, Hedysarum laeve and Hedysarum scoparium, the three aerial-seeding plants;2) Patterns of Artemisia ordosica under different phases; and3) The influence degree to soil crust thickness caused by Artemisia ordosica under different conditions. The analysis shows:1、Artemisia ordosica’s aggregated distribution was stronger on fixed sandy land than on semi-fixed sandy land, which was caused by the less soil moisture of fixed sandy land. Aggregated distribution could help inhibiting other population reproduction, and surviving in poor conditions. On the semi-fixed sandy land, aggregated distribution was relatively weak for the sufficient soil moisture.2、Hedysarum laeve’s aggregated distribution was stronger on semi-fixed sandy land than on fixed sandy land. That’s because the number of Hedysarum laeve was less on fixed sandy land than on semi-fixed for the lack of soil moisture, and lower number would cause the decline of aggregated distribution. Hedysarum laeve is a cloned guerrilla plant with big distance between each plant, and the root system can reach2meters underground for water. So the distance would getting bigger on fixed sandy land, which cause the weaker aggregated distribution. There were more Hedysarum laeve on semi-fixed than fixed sandy land. The fixed sandy land had obvious soil crust, in which case, soil moisture transmission was affected and the shrubs with deep roots would recession for the lack of soil moisture.3、Hedysarum scoparium was aggregated distribution both on fixed and semi-fixed sandy1and, so aerial seeding would be suitable for Hedvsarum scoparium. On the semi-fixed sandy la nd, there was competitive relation between lower age-class Artemisia ordosica and Hedysarum s coparum. 4、Aerial seeding Artemisia ordosica on sandy land would go through three phases:With t he growth of Artemisia ordosica, sandy land would become from semi-fixed sandy land to fixe d sandy land, and then to the nature Artemisia ordosica land. On the nature sample plot, live, half-dead and dead Artemisia ordosica were all aggregated distribution. The competition between live and half-dead Artemisia ordosica would getting more obvious if the distance between diff erent age-class was bigger. Artemisia ordosica with higher age-class would restrain the growth of that with lower age-class.5、Artemisia ordosica had significant impact on the soil crust thickness. The crown diamet er was bigger, the crust nearby was more thickness.