Abstract: To determine the change of soil dissolved organic carbon (DOC) following grassland afforestation, the authors compared soil DOC, soil organic carbon (SOC) and soil total N (STN) of top 30cm soils under Leymus chinensis meadow steppe, Pinus sylvestris var. mongolica plantation, and Larix principis-rupprechtii. plantation in Saihanba, Hebei Province. DOC, SOC and STN of coniferous plantation soils were less than those of meadow steppe soils; DOC, SOC, and STN decreased following 40-year grassland afforestation. Soil heterogeneities of coniferous plantations were lower than meadow steppes.

Key words: afforestation, dissolved organic carbon, soil organic carbon, soil total nitrogen

摘要： 为了解天然草地造林后土壤可溶性有机碳的变化，以河北塞罕坝的羊草草甸草原以及在草甸草原上营造的樟子松人工林和落叶松人工林为研究对象，比较了3种植被类型土壤表层0-30cm的土壤可溶性有机碳、土壤总有机碳和土壤全氮等指标。结果表明，人工针叶林的土壤可溶性有机碳、土壤有机碳和土壤全氮含量均低于草甸草原，天然草地营造人工针叶林40年后土壤可溶性有机碳、土壤有机碳和土壤全氮都有所下降，人工林生态系统的土壤异质性低于草甸草原。

关键词: 草地造林, 土壤可溶性有机碳, 土壤总有机碳, 土壤全氮