Funding for this research was provided by:
National Natural Science Foundation of China (30560013)
Received: 11 March 2020
Accepted: 17 September 2020
First Online: 9 October 2020
Ethics approval and consent to participate
: 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 that they have no competing interests.