Abstract:

Pinus tabulaeformis is one of the most important forest species in the warm temperature humid and semi humid climatic region in China. The information of the soil quality properties are essential for sustainable management of
Pinus tabulaeformis plantations. In 2005, the change of soil quality with the forest age was investigated with a chronosequence method in the Pinus tabulaeformis stands of 21, 29 and 36 year old in middle hilly area of Yingpan, Yanqing Country of Bejing. The results showed that the integrated fertility index (IFI) of the soil was respectively 0.579, -0.456 and-0.123 in the 21, 29and 36year old plantations. The soil physical properties were deteriorated in the 29year old stands, while the content of soil nutrient such as organic matter, total N and available P was degraded in the 36yearold stands. Also, the soil quality was mainly determined by forest age, and also influenced by forest density. The value of the coefficient of variance in the 21, 29and 36yearold stands was respectively 0192,-1361 and-2407, which suggested that the relative older stands were more sensitive to the forest density and its thinning intensity should be accordingly minor. Additionally, it was found that soil alkaline phosphatase, invertase, organic C, available K could be regarded as indicators to assess the change of soil quality related to forest secondary succession.

Key words: plantation, forest age, soil quality, complementary evaluation