Compositional characteristics and roles of soil mineral substances in depressions between hills in karst region. - HAN Mei-rong; SONG Tong-qing; PENG Wan-xia; HUANG Guo-qin; DU Hu; LU Shi-yang; SHI Wei-wei (Chinese Journal of Applied Ecology / Yingyong Shengtai Xuebao, 2012)