Funding for this research was provided by:
Natural Science Foundation of China (81573545)
Received: 29 July 2020
Accepted: 9 March 2021
First Online: 23 March 2021
: The authors asked for permission from the local authorities and the people interviewed to carry out the study.
: The people interviewed were informed about the study’s objectives and the eventual publication of the information gathered, and they were assured that the informants’ identities would remain undisclosed.
: The authors declare no competing interests.