Interspecific associations of plant populations in rare earth mining wasteland in southern China

- The interspecies associations of species pairs closed with increasing natural revegetation.

Currently, there is limited research regarding revegetation in ion-adsorption rare earth mining wastelands, although this is essential for sustainable mining. We conducted a field survey to investigate species composition and interspecific associations in naturally rehabilitated vegetation in a rare earth mining wasteland in Xinfeng, Jiangxi Province, China. The interspecific associations of major species were quantitatively analyzed using a 2 × 2 contingency table, variance ratio, χ2 test, and interspecific association coefficients. The results showed that, as the time of natural rehabilitation increased from 5 years to 15 years, the overall interspecific associations changed gradually from negative to positive. The succession of naturally rehabilitated plant communities in mining wasteland changed over time and gradually became stable. However, no significant correlation was found between most pairs of species, indicating that the communities had simple structures, and were still in the early stage of succession. These findings suggest that planted communities are more effective at speeding up succession than naturally colonized communities in the initial stage of vegetation restoration in this rare earth mining wasteland. The first three species with the highest importance values were Pinus massoniana (0.72), Miscanthus floridulus (0.30) and Dicranopteris dichotoma (0.18). The interspecific association coefficients for P. massoniana-M. floridulus, P. massoniana-D. dichotoma and M. floridulus-D. dichotoma pairs, which increased with rehabilitation time, were 0.41, 0.64 and 0.45, respectively. Therefore, the dominant species, such as P. massoniana, M. floridulus and D. dichotoma, are recommended for mixed planting.