紫茎泽兰入侵对土壤酶活性和理化因子的影响

紫茎泽兰是我国危害最严重的外来入侵植物之一，为探明其入侵对土壤肥力的影响，比较研究了紫茎泽兰、云南菅、狗尾草群落和撂荒地下0~30 cm的4层土壤中6种酶活性和12种理化因子。结果表明群落类型和土壤深度对测定的各参数均有显著影响。随土壤深度的增加，多酚氧化酶、碱性磷酸酶、脲酶活性，以及有机质、全氮、全磷、全钙、水解氮、有效磷、速效钾含量和pH值均降低。总的看来，紫茎泽兰群落下碱性磷酸酶和脲酶活性，有机质、全氮、全磷、全钙、水解氮和有效磷含量，以及pH值均较高，全钾含量较低，但速效钾含量并不低，表明紫茎泽兰入侵多年后土壤肥力水平提高，形成了对其生长有利的土壤环境。

Effects of Eupatorium adenophorum Sprengel invasion on Soil Enzyme Activities and Physical and Chemical Factors

Eupatorium adenophorum is one of the most noxious invasive weeds in China.To explore the effects of this weed invasion on soil fertility,the activities of six enzymes and 12 physical and chemical factors were compared among the soil within 0~30cm depth under a more than 10 years old invaded grassland by E.adenophorum,a secondary grassland(abandoned maize field in November of 2001),a primary grassland of Themeda yunnanensis and a two years old artificial grassland of Setaria sphacelata.The results showed that each variable measured in this study changed significantly among communities and soil layers according to a two-way ANOVA.The activities of polyphenol oxidase,alkaline phosphatase and urase,the contents of organic matter,total N,total P,total Ca,hydrolytic N,active P,active K,and pH value decreased with the increase of soil depth.In general,the activities of alkaline phosphatase and urase,the contents of organic matter,total N,total P,total Ca,hydrolytic N,active P,and pH value were higher in the soil under E.adenophorum community compared to the soils under other communities.Total soil K content was lower in the soil under E.adenophorum than in the soils of other communities,while the active K content was similar among the four communities.These results indicate that E.adenophorum invasion for more than 10 years can increase soil fertility,create favorable soil conditions for itself.