Study On The Population Characteristics Of Three Sandy Subshrub Species Of Artemisia L. In Horqin Sandy Land

Artemisia halodendron, A. wudanica and A. sphaerocephala are important sand-fixation plants in arid desert zone and also the constructive species and the dominant species of sandy vegetation. In this paper, we selected Horqin sandy of Wengniute Banner of Chifeng City in Inner Mongolia as study area, mainly studied the architectural characteristics and sand-fixation efficiency, reproductive allocation, population structure and spatial distribution of the three plants, the results as follows:1.The branch length of the three species is becoming shorter with the decrease of the branch grade. A. wudanica decreases most obviously, and the length of first grade branch is obviously shorter than the others, the total bifurcation ratio and the gradual bifurcation ratio are all minimum. The branching angles of A. sphaerocephala are bigger, and branch could take full advantage for space resource.2. Based on the roughness concentration (Lc) to analyze the sand-fixation effect of three plants, A. sphaerocephala’s Lc value is highest in the study area, A. halodendron is close to with A. wudanica. It reflects that the A. sphaerocephala in the western Horqin Sandy Land has better population sand-fixation efficiency.3. A. wudanica and A. sphaerocephala begin to reproduce from the 2 age, and A. halodendron begin to reproduce from 3 age. The average individual reproductive allocation proportion of three species are 13.74%,48.76% and 24.13% respectively, and A. sphaerocephala greater than the other two kinds of plants. The reproductive allocation of three species has a certain relationship with age. A. halodendron with the increase of ages, the reproductive allocation proportion kept rising following the 3 age; A. wudanica will also ascend with age, and reach the maximum at 4 age, while fall again at 5 age; A. sphaerocephala’s reproductive allocation proportion rises apparently from the 2 age, and reaches to the stable state after 4 age.4. On the windward slope and semi-fixed sany land, A. halodendron population belongs to the stable population; for fixed sandy land on the leeward slope, and A. halodendron age structure will be a declining type. Age structure of A. wudanica basically belongs to pyramid which is on the windward slope, showing the characteristics of the increasing population, however the individual number of 2 age was significantly small; on leeward slope and semi-fixed sany land, presented the characteristics that transfers increasing type into stable population. For A. sphaerocephala age structure, on the windward slope and semi-fixed sandy land, has the character of increasing type population; on the leeward slope, the sand has been fixed, and age structure is the declining type, and the age of 1 or 2 individuals are extremely rarely. Three kinds of plants are all showed the tendency that develop to stable or declining type with the sand fixation.5. The population distribution pattern of A. halodendron in semi-fixed sand is a cluster distribution; in the fixed sand, the population distribution pattern has changed obviously, from the cluster into a random distribution. A.wudanica’s population distribution pattern is a cluster distribution both in the shifting and semi-fixed sandy land. A. sphaerocephala’s population distribution pattern in semi-fixed sandy land are cluster distribution, with the increase of the degree of sand fixation, in fixed sandy land A. sphaerocephala’s population distribution tend to uniform distributed.