Abstract:

The dynamic changes of soil fertility of different ground clearances are studied through the fixed position observation of twelve run-off plots for six years. The results show that the great differences between the soil fertility of control burning and that of non-burning are resulted by the different ground clearances. The soil fertility was increased by control burning shortly and decreased rapidly because of the erosion till the stand closed. According to the dymamic changes of soil fertility in control burning site, three soil fertility periods are designiated. Control burning periodically in same land is main factor that causes soil degradation of Chinese fir timber plantation. Where as the nutrient were enriched in surface layer of non-burning land and soil fertility was improved due to the decomposition of site slash.The changes of soil fertility of non-burning land in six years also can be devided into three periods but quite different from that of the control burning.

Key words: Ground clearance, Control burning, Chinese fir, Soil fertility