BASIC FEATURES OF FOREST STEPPE IN THE LOESS PLATEAU OF CHINA

摘要

The Loess Plateau is situated at 33°43′ — 41°16′N, 100°54′ —114°33′ E. It is covered with 50 — 150m deep loess. As it is eroded by flowing water for a long time, it formed alone hill-gully topography. Humidity and heat decrease by degrees from southeast to northwest, the forest is replaced by the steppe, and an obvious transitional zone formed between them, it is forest steppe. Its characteristic is that stunted xero-mesophilous trees distribute sparsely on the meadow steppe, the meadow steppe mainly consist of xero-mesophytes and meso-xerophytes, the trees cover degree isn' t over than 20%, usually about 10%, sometimes below than 5%. A precipitation of about 420-520mm is a decisive factor of existence of the forest steppe in the Loess Plateau.