The Changes of Nutrient Content and It’s Effect on Forest Growth on the Soil Degraded by Successive Crop of Japanese Larch

The changes of soil nutrients content and their effect on the forest growth on the soil degraded by the successive crop of Japanese larch (Larix kaempferi) were investigated with the data from 48 sample plots in Liaoning and Heilongjing Province in 1995. The results showed that (1) The nutrient content in the soil of different crop plantation of Japanese larch is different.The nutrient content of available N, total N, organic matter of the second crop plantation is lower than that in the soil of first crop.(2) The amount of 3 kinds of microbes (bacteria, fungi, rag fungus) in the second crop plantation’s soil is lower than that in the first crop plantation’s soil.(3) The growth (D and H) of different crop plantations is different.Whether it’s 12 year old or 3 year old, the average tree height and DBH of the second crop reduced by 2%～10% and 6%～13% compared with those of the first crop plantation respectively.