大兴安岭北部4种沼泽湿地土壤活性氮质量分数变化特征

Variation Characteristics of Soil Active Nitrogen Content in Four Swamp Wetlands in the Northern Da Hinggan Mountains

选择大兴安岭北部4种沼泽湿地(毛赤杨沼泽、苔草沼泽、落叶松-苔草沼泽、落叶松-苔藓沼泽),研究不同沼泽类型、月份、土层土壤活性氮质量分数的变化规律及影响因子。结果表明:6—10月,大兴安岭北部4种沼泽类型土壤铵态氮质量分数呈波动式下降,波动范围在0.71~15.03 mg·kg^(-1);土壤硝态氮质量分数在观测期内均呈波动式下降,波动范围为0.35~3.30 mg·kg^(-1)。毛赤杨沼泽、苔草沼泽各土层微生物量氮质量分数均表现为6月、10月相对较低;2种落叶松沼泽表层(0<h≤10 cm)土壤微生物量氮质量分数则表现为9月最低,分别为15.86、22.58 mg·kg^(-1)。4种沼泽湿地土壤可溶性有机氮质量分数在6-10月波动性较大,且规律性不强,波动范围为5.15~38.66 mg·kg^(-1)。除苔草沼泽8月表层土壤铵态氮质量分数低于10 cm<h≤20 cm土层外,其他沼泽类型均表现为0<h≤10 cm土层土壤铵态氮质量分数高于10 cm<h≤30 cm土层土壤。相关分析表明,4种沼泽湿地土壤活性氮除与土壤温度相关性较差外,与其他因子多呈显著或极显著正相关。大兴安岭北部4种沼泽土壤活性氮质量分数差异较大,土壤有机碳和微生物量碳是影响沼泽湿地土壤活性氮的主要因子。

Four swamp wetlands in the northern Da Hinggan Mountains(Alnus sibirica wetland,Sedge wetland,Larix gmelinii-Carex schmidtii wetland and Larix gmelinii-Moss wetland)were selected to investigate the variation and the influencing factors of soil active nitrogen mass fraction in different swamp types within different months and different soil layers.The results showed that the soil ammonium nitrogen and nitrate nitrogen contents of four swamp types in the northern Da Hinggan Mountains shows a decreased trend from June to October,with a range of 0.71-15.03 and 0.35-3.30 mg·kg^(-1),respectively.The microbial biomass nitrogen content in each soil layer of Alnus sibirica wetland and Sedge wetland in June and October were relatively low,while the microbial biomass nitrogen content at the surface soil of two Larix gmelinii swamps in September were the lowest,with the 15.86 and 22.58 mg·kg^(-1),respectively.The soluble organic nitrogen content in the four types of swamp wetlands soil fluctuates greatly from June to October,with a fluctuation range of 5.15-38.66 mg·kg^(-1),and there is not obvious regularity.Except that the ammonium nitrogen mass fraction at the surface soil of the Sedge wetland was lower than that of the 10 cm<h≤20 cm layer in August,the ammonium nitrogen content at 0<h≤10 cm soil layer was higher than that of lower soil layer in other swamp types.By Pearson correlation analysis,the soil active nitrogen in the four swamp wetlands were significantly positive correlation with other factors,except for the soil temperature.The soil active nitrogen content in the four swamp in the northern Da Hinggan Mountains has great difference.Soil organic carbon and microbial biomass carbon are the main influencing factors of the soil active nitrogen content of swamp wetland.