Analysis On The Dominant Species Spatial Pattern Of Typical Desert Plant Communities On The Northwest Edge Of Junggar Basin

Population acting as the linkage between the plant individual and community, its mosaic structure in community is the important characteristic of the plant community. The structure not only reflects the ecological relationship among populations, but also indicates the ecological relationship between population and environment factors. On the basis of typical community plot investigation data, the study researched the population distribution pattern and interspecies relation of the dominant species using the plot sampling method which based on frequency or density and the plotless sampling method which based on distance on the northwest edge of Junggar Basin. The results as following:Through the analysis of the distribution indexes method, as for the same research object, the population distribution character in different scales which were reflect by different indexes focused on different aspects. While combining of several indexes can gaven multi-factor information. Using the analysis of the distribution indexes method, the results indicated that all distribution indexes of Halostachys caspica population, Haloxylon ammodendron population and Haloxylon persicum population accorded with congregated pattern within the scales of 1m×1m,2m×2m,4m×4m,8m×8m,16m×16m,32m×32m. And the T-test evidenced that the deviation from random pattern was obvious in 1~32m scale. Thus, according to research object and goal, choosing a reasonable distribution index can provide multi-factor information about the spatial pattern of the population. Meanwhile, the results also indicated that the type of population spatial pattern which was judged by the test of frequency distribution was restricted by sampling scale. Through the analysis of frequency distribution testing in 1~16m scale, Halostachys caspica population shown congregation pattern in 2m×2m,4m×4m,16m×16m scales. Haloxylon ammodendron population congregated within the scales of 4m×4m,8m×8m,16m×16m and Haloxylon persicum population congregated in 1m×1m,8m×8m scales. It can be seen from the above results that there was an inseparable relation between the spatial pattern of population and sampling scale. If using frequency distribution testing to judge population spatial pattern, spatial scale must be considerated.Using the spatial point-pattern analysis of Ripley's function, the result indicated that Halostachys caspica population of Ass.halocnemum strobilaceum-H.caspica community on the northwest edge of Junggar Basin shown congregative pattern in 0~50m scale.But Halocnemum strobilaceum population shown congregative pattern in the same scale or the less scale. And there was a positive, no relation and negative relation change series in space between Halostachys caspica and Halocnemum strobilaceum. While in Ass.haloxy persicum-H.ammodendron communities, either Haloxylon ammodendron population or Haloxylon persicum population, the spatial pattern was also congregative in 0~50m scales.While sometimes there was a transition from congregative pattern to regular pattern between them. There was a negative or positive, no relation and negative relation change series between Haloxylon ammodendron and Haloxylon persicum. In Ass.Haloxylon ammodendron-H.persicum communities, Haloxylon persicum population had a transition from congregative pattern to regular distribution within the scales of 0~50m, while Haloxylon ammodendron population was congregative pattern. There was a negative, no relation and positive relation change series in space between Haloxylon persicum and Haloxylon ammodendron. As for single dominant species commimity, either Halostachys caspica commimity or Haloxylon persicum commimity, the spatial pattern was all congregative pattern in 0~50m scale.