东北近天然落叶松云冷杉林不同间伐强度土壤肥力研究
Soil Fertility in Semi-natural Mixed Larch-spruce-fir Stands under Different Thinning Intensities

基于吉林省汪清林业局金沟岭林场5个区组共20块近天然落叶松云冷杉林样地0~10 cm、10~20 cm、20~40 cm和40~60 cm的土壤采集及理化性质测定，运用主成分分析法对不同间伐强度下（0%、20%、30%和40%）的土壤肥力进行综合评价，分析讨论了间伐强度对各土壤肥力因子和综合土壤肥力的影响。结果表明，间伐强度对土壤pH值、有机质、全N、全P、全K和速效K影响显著（p<0.05），而对土壤密度、含水量、有效P和CEC的影响不显著（p>0.05）；各土壤肥力因子之间具有一定的相关性，有机质、有效P、速效K、全N和全P各肥力因子之间均呈极显著正相关，全K与全P极显著正相关，而与有机质和全氮极显著负相关，CEC与有机质和全N极显著正相关；根据不同间伐强度土壤肥力综合评价得分，土壤肥力状况由高到低依次为30%、20%、对照、40%。
Twenty plots in five blocks were selected in Jingouling Forest Farm administrated by Wangqing Forestry Bureau, Jilin Province. Soil samples were collected at the depths of 0-10 cm, 10-20 cm, 20-40 cm and 40-60 cm for the determination of their physico-chemical properties. Comprehensive evaluation of soil fertility under different thinning intensities (0%, 20%, 30% and 40%) was made with principal component analysis method, and the effects of thinning intensity on soil fertility were analyzed. The results showed that thinning intensity had significant effects on soil pH, organic matter, total nitrogen, total phosphorus, total potassium and readily available potassium (p<0.05), but had no significant effects on soil bulk density, water content, available phosphorus and cation exchange capacity CEC (p>0.05). Certain correlations were found among soil fertility factors. There were very significant positive correlations between soil organic matter, available phosphorus, readily available potassium, total nitrogen and total phosphorus (p<0.01). Total potassium had a very significant positive correlation with total phosphorus, but very significant negative correlations with organic matter and total nitrogen; Very significant positive correlations were found between CEC and organic matter as well as total nitrogen. According to the comprehensive evaluation of soil fertility under different thinning intensities, soil fertility was from high to low in an order of 30%, 20%, control, 40%