Appropriate Removal of Forest Litter is Beneficial to <i>Pinus tabuliformis</i> Carr. Regeneration in a Pine and Oak Mixed Forest in the Qinling Mountains, China oleh Xueying Huo, Dexiang Wang, Deye Bing, Yuanze Li, Haibin Kang, Hang Yang, Guoren Wei, Zhi Chao