[Objective]In order to explore the ecological consequences caused by secondary earthquake disasters and to provide scientific evidences for disaster-affected soil restoration,the physical and chemical properties of forest soil in Li County,Sichuan Province,were investigated comparatively. [Method]Wenchuan earthquake happened on May 12 th , 2008 ,and the investigation and sampling in Cupressus chenginana plantation of disaster-affected area was conducted in November,2013. Three earthquake-affected stands and one stand as control ( no obvious damage caused by secondary earthquake disasters) were chosen in Xionger Mountain ( mountain cinnamon soil) ,and two earthquake-affected stands and one control stand were chosen in Puxi Gully ( mountain brown soil) . Soil physical properties such as soil density,total porosity and particle composition in 0 -20 cm soil layer were measured. Meanwhile,soil nutrient indices such as soil pH value,total nitrogen ( TN) ,alkali-hydrolysable nitrogen ( AN) ,available phosphorus ( AP) ,available potassium ( AK) , soil organic matter(SOM)content and cation exchange capacity (CEC) in three soil layers (0 -20,20 -40 ,and 40 -60 cm) were also analyzed. [Results]Soil density in 0 -20 cm soil layer was significantly increased in the earthquake-affected sites,the average value of earthquake-effected soils was 1. 28 g·cm -3 . In comparison with the controls,average values of soil density were increased by 6. 1% and 18. 6% in Xionger Mountain and Puxi Gully,respectively. The increased soil density caused the reduction of total soil porosity ( a significant negative relationship between them,r =-0. 998**) ,which brought in a reduction of soil water permeability and an increase of surface runoff and soil & water erosion. Affected by secondary earthquake disasters,the average soil organic matter contents were decreased by 56. 1%and 52. 2% in Xionger Mountain and Puxi Gully,respectively. Meanwhile,clay contents in surface soil (0 -20 cm) decreased by 54. 8% and 57. 1% on average,respectively. But soil sand and silt contents increased significantly. The soil pH values were significantly increased at different soil depths (0 -20,20 -40 ,and 40 -60 cm) in both of the two study sites,and the average pH value was increased by 11. 5%. The variability of pH value showed no significant relationship with the soil type and soil depth. The decrease of soil organic matter content and loss of soil clay content may be the main causes for the increase of pH value. Affected by secondary earthquake disasters,soil TN,AN,AP and AK contents were decreased significantly. The AP and AK contents were decreased by 67. 1% and 72. 2% in Xionger Mountain,meanwhile,decreased by 80. 3% and 78. 0% in Puxi Gully,respectively. Content of SOM was positively correlated with contents of TN,AN,AP,AK and CEC,respectively. The CEC values in earthquake-affected soils from both investigated areas were significantly decreased by 79 . 7% - 90 . 3%. The soils showed a very low capacity in maintaining soil water and nutrient. The changes of soil C/N ratio indicated that the C loss was higher than the N loss in earthquake-affected soils. [Conclusion]Affected by secondary earthquake disasters,the soils of Cupressus chenginana plantation in this study showed severe soil degradation: Increase of soil density,decrease of soil porosity,increase of soil pH value,loss of soil clay and nutrients and reduction of soil CEC. It is recommended that the soil remediation measures in the studied forest soils should be focused on the following aspects: increasing soil organic matter,improving soil water and nutrient retention,and reducing loss of soil clay.%【目的】通过对四川理县地震灾区不同受灾程度森林土壤理化性质的对比调查，探索地震对土壤的影响，为受灾地区土壤修复提供科学依据。【方法】2013年11月选取汶川地震受灾区岷江柏人工林地进行调查与采样，在熊尔山调查点(山地褐土)选取1个对照(未受地震次生灾害明显破坏)和3个受灾林分，在蒲溪沟调查点(山地棕壤)选取1个对照和2个受灾林分。测定表层土壤(0～20 cm)的密度、总孔隙度和颗粒组成特征，分析土壤剖面3个土层(0～20，20～40和40～60 cm)土壤的 pH值、全氮、碱解氮、有效磷、速效钾、有机质和阳离子交换量等养分指标。【结果】地震造成0～20 cm层土壤密度显著提高，受灾土壤密度平均值高达1.28 g·cm －3，与对照相比，熊尔山和蒲溪沟2调查点的土壤密度平均值分别提高6.1%和18.6%；伴随着土壤密度增大，土壤总孔隙度均显著减少(两者极显著负相关，γ=0.998＊＊)，导致土壤透水能力下降，地表径流和水土流失危险增大；受地震次生灾害影响，2调查点土壤有机质含量平均值分别下降56.1%和52.2%，表层土壤(0～20 cm )的黏粒含量分别平均下降了54.8%和57.1%，土壤砂粒和粉粒含量显著升高(P ＜0.05)；地震引起2个调查点各土层(0～20，20～40和40～60 cm)土壤 pH值显著升高(P＜0.05)，平均提高了11.5%，pH 值变化与土壤类型和土层深度相关性不显著，土壤有机质含量减少及黏粒流失可能是导致土壤 pH值升高的主要原因；受地震次生灾害影响，土壤全氮、碱解氮、有效磷和速效钾含量均显著降低，熊尔山土壤中的有效磷和速效钾含量分别减少了67.1%和72.2%，而蒲溪沟土壤中碱解氮和速效钾含量分别减少了80.3%和78.0%；土壤有机质含量与全氮含量、碱解氮含量、有效磷含量、阳离子交换量间均显著正相关；土壤的阳离子交换量显著减少，下降79.7%～90.3%，土壤保水保肥能力很弱；根据 C/N比的变化分析可知地震后土壤的 C 损失率高于 N 损失率。【结论】受地震次生灾害山体崩塌、滑坡、泥石流、土体断裂及掩埋等影响，调查林分的土壤均出现明显的退化现象：土壤密度升高，总孔隙度下降，土壤 pH值增大，黏粒流失十分严重，养分含量和阳离子交换量明显降低。建议该类林地的土壤修复应着重提高土壤有机质含量、改善土壤保水保肥性能和减少土壤黏粒流失等。
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