Abstract: To explore the allelopathic mechanism of Euphorbia jolkinii Boiss， a degradation indicator species of mountain meadows in northwest Yunnan， in this study we analyzed its effects on soil phosphorus transformation and related indicators by adding different concentrations of 4-Nitrophenol （4-NP） and 2-Phenethylamine （2-PEA） to the soil. The results showed that both allelochemicals significantly increased soil microbial biomass phosphorus， aluminum-bound phosphorus， calcium-bound phosphorus， and moderately reactive organic phosphorus content， decreased pH and iron-bound phosphorus， occluded phosphorus， moderately stable and highly stable organic phosphorus content （P<0.05）， and promoted the proliferation of bacteria and actinomycetes. 4-NP significantly enhanced phytase activity and reduced acid phosphatase activity. 2-PEA significantly increased acid phosphatase， phytase， and phosphodiesterase activities， while reduced alkaline phosphatase activity （P<0.05）. In summary， the addition of 4-NP and 2-PEA directly affects soil physicochemical properties， changes the content of organic and inorganic phosphorus components， indirectly achieves the accumulation of soil nutrients in its rhizosphere environment， and promotes its further expansion.

Key words: Euphorbia jolkinii Boiss, Allelochemicals, Mountain meadows, Soil phosphorus transformation

摘要： 为探究滇西北山地草甸的退化指示物种大狼毒（Euphorbia jolkinii Boiss）的化感作用机制，本研究通过在土壤中添加不同浓度的4-硝基苯酚（4-Nitrophenol，4-NP）和2-苯乙胺（2-Phenethylamine，2-PEA），分析其对土壤磷转化及相关指标的影响。结果显示，两种化感物质均显著提高了土壤微生物量磷、铝结合磷、钙结合磷和中等活性有机磷含量，降低了pH值及铁结合态磷、闭蓄态磷、中等稳定性与高稳定性有机磷含量（P<0.05），并促进细菌和放线菌繁殖。4-NP显著增强植酸酶活性而降低酸性磷酸酶活性；2-PEA则显著提高酸性磷酸酶、植酸酶和磷酸二酯酶活性，降低碱性磷酸酶活性（P<0.05）。综上，4-NP和2-PEA的添加会直接影响土壤的理化性质，改变有机磷及无机磷各组分含量，间接实现土壤养分在其根际环境中的积累，促进其自身进一步扩张。

关键词: 大狼毒, 化感物质, 山地草甸, 土壤磷转化