Molecular Detection of Rice Variant Lines Treated by Embryo-soaking of Alternanthera philoxeroides DNA Solution and Their Drought Resistance Evaluation Site Classification and Evaluation of Teak Forests in Hainan Island THE STUDY ON THE SITE CLASSIFICATION AND ITS EVALUATION AT FOREST LAND IN THE PLAIN FORMERLY FIOODED BY THE HUANGHE RIVER Evaluating Site Quality for Secondary Forests and Plantation in Qinling Mountains