关键词: 荒漠草原, 柠条, 优势草本, 点格局分析, 空间关联性

Abstract: Diverse ecological processes lead to changes in the spatial pattern of populations， which in turn affect the spatial associations between species. The natural succession from a single sand-fixing shrub composition to a shrub-grass composite vegetation structure is one of the long-term management goals of artificial sand-fixing vegetation systems in arid regions. In this paper， point pattern analysis were employed to investigate the spatial relationships between Caragana korshinskii and dominant herbaceous plants within C. korshinskii sand-fixing plant communities along the southeastern fringe of the Tengger Desert over a period of 30 to 40 years， as well as the spatial relationships among the dominant herbaceous plants themselves. The results showed that （1） The dominant shrub C. korshinskii exhibited a uniform and random distribution within the scale of the study， with intense intraspecific competition. Dominant herbs show strong population effects at a small scale， manifesting as clumped distribution. As the scale increases， intraspecific competition among dominant herbs intensifies， and the spatial pattern gradually shifted towards a uniform and random distribution. （2） From an overall perspective， the community composed of the C. korshinskii population and the dominant herbaceous plant populations showed no significant spatial association within most of the study scale. The C. korshinskii and Artemisia scoparia populations were uncorrelated across the entire study scale. The C. korshinskii with Cynodon dactylon， C. korshinskii with Bassia dasyphylla， and C. korshinskii with Chloris virgata populations exhibited a relatively clear negative association at a scale of 9.4 to 10 meters， indicating mutual exclusion between species. The C. korshinskii and Eragrostis minor population showed a clear positive correlation at a scale of 7.8 to 10 meters， suggested a symbiotic relationship between the species. （3） The spatial association among different dominant herbaceous plants was more complex， and the spatial associations between different population combinations also varied. As the study scale increases， the spatial association among different dominant herbaceous plants tends to become non-correlated. The interspecific relationships among different dominant herbs changed sharply with the variation in the study scale， and then gradually moderate. In summary， as indicated by spatial distribution relationships， within the C. korshinskii sand-fixing community， intraspecific competition was predominant among C. korshinskii individuals， while dominant herbaceous plants showed symbiotic relationships at a small scale and competition at a larger scale. The spatial relationships between C. korshinskii and dominant herbaceous plants were relatively complex， often tending towards non-correlation. The shrub-herb vegetation configuration of C. korshinskii sand-fixing communities with an age of 30 to 40 years still exhibited a strong degree of randomness， and there remained a significant gap in the construction of stable communities， as indicated by the strong interspecific interactions between shrubs and herbs.

Key words: Desert steppe, Caragana korshinskii, Dominant herbaceous plants, Point pattern analysis, Spatial association