The Upper Yellow River City Cluster is the highest form of urban spatial organization in Northwest China, and it is the region with the closest exchange of materials, information and people among the cities in the upper Yellow River. In this paper, the gravity model was optimized and improved in terms of two dimensions, such as the assessment of the comprehensive strength of cities as well as the absolute and relative linkage strength, and the improved gravity model was used to evaluate the characteristics of urban spatial linkages of 10 cities in the Upper Yellow River City Cluster from 2018 to 2021, and to analyze their spatial patterns and evolution. The results show that large cities in the Upper Yellow River City Cluster show more radiation effects, while small cities are more attracted by external cities. With the passage of time, the strength of the connection between cities has been strengthened, gradually forming a spatial pattern of transition from “single nucleus” to “multiple nuclei”, with the spatial layout showing one center, three circles, three nuclei in the shape of V, and the Yellow River becoming an axis and cities being in the same belt, and the spatial pattern of the cities can be classified as follows Three groups, such as Lanzhou City Group, Yinchuan City Group, Xining City Group. There is a big difference in the development of each cluster, and it is urgent to find the development path to realize the differentiated development.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |