Keywords: 
• forest soil science /
• Phyllostachys praecox stands /
• intensive cultivation management /
• microbial biomass

Abstract: Phyllostachys praecox，a favorite bamboo species with high economic value from its edible shoots，has often been intensively managed resulting in great gains for the farmers，yet compared to traditional management there is a serious bamboo degradation problem. The objective of this study was to analyze the effects of long-term intensive management on soil microbial biomass in P. praecox stands. A field survey was conducted with soil samples taken from 5-，10-，and 15-year old intensively managed bamboo stands in Hengfan and Xitianmu Towns，along with new，1-year-old stands on converted paddy fields （control）. Results indicated that，after long term intensive management，total organic carbon （TOC），total N（TN），available N，total phosphorus（TP），and available P in soils（0 - 20 cm） significantly increased（P＜0.05），whereas pH significantly decreased（P＜0.05） with prolonged plantation times. Compared to the control，soil microbial biomass carbon（MBC） and microbial biomass nitrogen（MBN） significantly decreased（P＜0.05），and the ratios of MBC/TOC and MBN/TN also decreased from 1 to 15 years. Microbial biomass phosphorus（MBP） increased in the first 5 years after the paddy fields converted to P. praecox stands，but with no significant difference，and then decreased gradually with the ratio of MBP/TP from 1 to 15 years gradually decreasing with progressively older plantations. This study showed that long-term fertilization and winter mulch restrained soil microbial activity，decreased soil biological properties，and led to early degradation of P. praecox stands.［Ch，4 tab. 22 ref.］