Funding for this research was provided by:
Ministry of Science and Technology of the People's Republic of China (No.2019QZKK0502)
Chinese Academy of Sciences (XDA20050204, XDA19050301, and XDA19050303)
Received: 3 April 2020
Accepted: 21 July 2020
First Online: 31 August 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.