Soil Carbon and Nitrogen Properties in an Alnus formosana Forest-Grass Complex Ecosystem | 台湾桤木林草复合生态系统土壤碳氮特征

chinois. 【目的】了解不同台湾桤木林草复合生态系统土壤碳氮特征，探讨林草复合模式对土壤碳氮库的影响．【方法】以四川省丹棱县退耕还林地台湾桤木＋扁穗牛鞭草（Hemarthria compressa）、台湾桤木＋黑麦草（Lolium multiflorum）和台湾桤木＋自然草（林下自然生长的杂草）3种模式为研究对象，采用土钻法分土层采集各模式下土样，研究其土壤有机碳和全氮特征。【结果】不同林草模式对土壤有机碳和全氮的影响程度并不一致。3种模式土壤有机碳和全氮含量表现出：台湾桤木＋牛鞭草＞台湾桤木＋黑麦草＞台湾桤木＋自然草，全氮含量差异显著（P＜0.05）。各模式有机碳和全氮含量均随土层增加而显著降低（P＜0.05）。3种模式土壤剖面平均C/N表现出：台湾桤木＋牛鞭草＞台湾桤木＋自然草＞台湾桤木＋黑麦草，各模式间C/N差异显著（P＜0.05）。【结论】林草复合模式能较好地改善土壤肥力，这为区域退耕还林林草模式水肥管理提供了理论依据。

anglais. 【Objective】Our aim is to understand properties of soil carbon and nitrogen in an Alnus formosana forest-grass complex ecosystem, and to explore the influence of forest-grass system on soil carbon and nitrogen pools. 【Method】Three models, alder （Alnus formosana） ＋ ryegrass （Lolium multiflorum）, alder （Alnus formosana） ＋ limpograss （Hemarthria compressa） and Alnus cremastogyne ＋ natural grass were chosen in this study. Soil samples of each model were collected using soil auger. Moreover, organic carbon and total nitrogen were analyzed.【Results】The effect size of vegetation on soil organic carbon and nitrogen was different among the three models. The order of soil organic carbon and nitrogen of three models is alder ＋ limpograss model〉alder＋ ryegrass model〉pure alder forest. There was significant differences in soil nitrogen content between two forest-grass models and natural grass system （P〈0.05）. The contents of soil organic carbon and nitrogen decreased with the increase in soil depth （P〈0.05）. The soil C/N of three models was alder ＋ limpograss〉pure alder forest〉alder＋ ryegrass. Significant differences in C/N were observed among the models （P〈0.05）. 【Conclusion】Forest-grass complex system can effectively improve soil fertility. This provides a theoretical basis for fertilizer and water management of forest-grass complex ecosystem.