Community Characteristics And Spatial Pattern Of Artemisia Arenaria On Different Sites In Semi-arid Desertification Areas

Artemisia arenaria is an excellent semi-shrub for sand fixation in desert areas in China. It owns remarkable adaptability, ability of fast-growing and anti-wind erosion. It is also drought-enduring and able to endure infertility. What's more important, Artemisia arenaria plays a great role in the stability of the sand landscape. Meanwhile, the plant community spatial pattern and community characteristics are significant methods to study the interactions existing among the communities and what's going on between the vegetation and invironment. It has great value to analyze the community spatial pattern and community characteristics for the function study of plant ecological system to crystallize the growing condition of Artemisia arenaria in different stand sites. What's more, it can provide guideline in theory on how to choose the best plant site type and patterns, eventually make great contribution on preventing and control desertification. For this reason, the thesis choose 5 kinds of stand conditions, which include the windward slope, the leeward slope, the flat sand, the counterfeit Gebi covered by amount of coarse gravels and the sandy land among the dunes, to investigate the following contents:(1)community characteristics and comprehensive vigior indexes of Artemisia arenaria in different site conditions; (2)the size structure and dynamic changes of Artemisia arenaria in different site conditions; (3) the horizontal and vertical community spatial distribution pattern of Artemisia arenaria in different site conditions. The main conclusions in this thesis have been summarized as follows.(1)As far as the vertical distribution of Artemisia arenaria population in different site conditions is concerned, the average height of the Artemisia arenaria on the flat sand is the highest, which is 47cm, and most of them is between the 40-60cm high. But the height of Artemisia arenaria population in other stand conditions focus on the 0-20cm with a ratio of more than 40%.(2)Through analyzing the size structure of Artemisia arenaria population, the Artemisia arenaria population in the windward slope, the leeward slope and the counterfeit Gebi covered by amount of coarse gravels are in stable phases. It showed the population adapted to local habitat conditions and was able to complete the natural regeneration under natural conditions. The Artemisia arenaria population in flat sand and the sandy land among the dunes are in recession stages. It explained that the population can achieve maximize the expansion of their own survival by using the local environmental conditions, but it has developed to the bottleneck.(3)The best growing standing site are windward slope and the counterfeit Gebi covered by amount of coarse gravels, which are going through badly wind erosion and sand-burying. What's more, the Artemisia arenaria on the counterfeit Gebi is in the best life condition, and then the Artemisia arenaria on the windward following. On the contrary, due to the side effects by amount of soil crust, the leeward slope, the flat sand place and and the sandy land among the dunes are not good for Artemisia arenaria growing.(4)The spatial distribution pattern types of the study area of Artemisia arenaria population in different site conditions, except the sand land, are aggregation distribution, but there is a difference in the cluster size. the cluster size of leeward slope is the highest. The reasons of difference in the distribution pattern include the age structure, the breeding stradgy, the different standing site type and so on.