Funding for this research was provided by:
the Fundamental Research Funds for the Central Universities (YX-201410)
the Normal Sustainability Fund for Taiyueshan Long-Term Forest Ecology Research Station (2017-LYPT-DW-148)
Received: 5 January 2018
Accepted: 13 February 2018
First Online: 14 March 2018
: The authors declare that they have no competing interests.