Figure.7 Betweenness centrality of nodes in oasis transition network during various periods

4.4 Oasis structural stability analysis

The oasis structural stability was assessed by the average path length for all the sub-periods in the oasis transition network. If the average path length was longer, the transition between the oasis types was more difficult, and the oasis had a stronger structural stability. In Table 2, the average path length of the oasis transition networks was all shorter than 1.5 in the seven sub-periods, implying an unstable structure of the oasis system. Additionally, the average path length of the oasis transition network descended from 1.47 to 1.20 in 1990-2020, which demonstrated the oasis system became increasingly unstable.
The average path length decreased by 5.44% between 1190-1995 and 1995-2000, and kept stable during 1995-2010. In this period, cropland areas expanded significantly, and many efforts like planting. However, the average path length decreased to 1.20 during 2010-2020, which indicated transitions among different land types were easier and oasis transition network was more complex.