STUDY ON CHANGES OF SOIL FERTILITY AS AFFECTED BY THE REPLACEMENT OF BROADLEAVED STAND BY CHINESE FIR STAND IN NANPING
南平溪后杉木林取代杂木林后土壤肥力变化的研究

The changes of soil fertility in a 70 year old fast-growing,highyield Chi-nese fir stand,which was originally occupied by a broadleaved stand,were studied for 2 consecutive years in Anchaoxia,Qihou,Nanping The results show-ed that the soil fertility of the 70-year-old fast-growing high-yield-Chinese fir stand had declined obviously. In comparison with the original broad-leafed forest stand,the Chinese fir site showed increased soil bulk density, decreas-ed soil organic matter content and nutrient element concentrations, and dimi-nishing soil enzyme and other biological activities.The reason that the 70-year-old Chinese fir stand still maintains relatively high fertility is that the increased undercanopy space facilitates the maintenance of high species dive-rsityand biomass production.