6. Conclusion

In this study, oasis spatial-temporal variations in Tuha Basin were first analyzed for the further transition investigation over the past 30 years. All the oasis types increased from 1990 to 2020, and the natural oasis expanded the most. Oasis transition processes, key land type and oasis structural stability were then depicted using the constructed oasis transition network. We concluded that the oasis transition relationship among different oasis types became more complicated in 2020 than that was in 1990. Grassland, shrubland, forest and cropland changed the most during the study period, and grassland was viewed as the key land type due to the high out-degree, in-degree values and betweenness centrality. The oasis structural stability calculated from the network showing declining trend from 1990 to 2020. To explore the driving forces of oasis changes, correlation analysis between the natural and human factors and oasis changes was conducted using the Pearson coefficient. Among the natural driving factors, temperature correlated positively with natural oasis changes, and had insignificant effects on artificial oasis. In human driving factors, population, the total power of agricultural machinery, raw coal production, and the total agricultural output improved the growth of shrubland and the artificial oasis; built-up showed the most positive response to human driving factors. The study clarified the oasis transition pattern and process, and provided scientific reference for future oasis study and management.