Funding for this research was provided by:
National Natural Science Foundation of China (31570614)
the Forestry Science and Technology Innovation Project of Shandong Province (2019LY009)
Text and Data Mining valid from 2019-10-31
Received: 11 October 2019
Accepted: 17 October 2019
First Online: 31 October 2019
Ethics approval and consent to participate
: This article does not contain any studies with human participants or animals performed by any of the authors.
: All authors agree with the contents of the manuscript and its submission to the journal.
: The authors declare that they have no competing interests.