养分添加和浅耕翻对晋北赖草草地土壤呼吸的影响

Effects of Nutrient Addition and Shallow Tillage on Soil Respiration in Leymus secalinus Grassland of Northern Shanxi Province

为了探究外源养分输入和人为干扰及其交互作用对农牧交错带草地土壤呼吸的影响,本研究以晋北农牧交错带草地为研究对象,设置对照、养分添加(氮磷钾NPK)、浅耕翻(15 cm)和养分添加+浅耕翻4个处理进行探究。结果表明:养分添加使土壤呼吸提高了39.0%,而浅耕翻对其无显著影响;浅耕翻和养分添加的交互作用对土壤呼吸的影响与年际降水有关,在湿润年份(2020),浅耕翻增强了养分添加对土壤呼吸的正效应,干旱年份(2021)削弱;结构方程模型的结果表明,土壤呼吸的变化与地下生物量有关;浅耕翻和养分添加处理对土壤呼吸温度敏感性无显著影响,养分添加+浅耕翻处理对土壤呼吸的温度敏感性无显著影响但存在明显的年际差异。综上所述,探究农牧交错带草地养分管理及人为干扰对土壤碳通量的影响应考虑年际降水的变化。

In order to explore the effects of exogenous nutrient input,human disturbance and their interaction on soil respiration in a grassland in agro-pastoral zone,this study took the Leymus secalinus grassland in agro-pastoral belt in northern Shanxi Province as the research object.In this study,four treatments,control,nutrient addition(NPK),shallow tillage(15 cm)and nutrient addition+shallow tillage,were set up to explore the responses of that Leymus secalinus grassland.The results showed that nutrient addition increased soil respiration in that grassland by 39.0%,while shallow tillage had no significant effect on it.The effect of interaction between shallow ploughing and nutrient addition on soil respiration was related to interannual precipitation.Shallow ploughing enhanced the positive effect of nutrient addition on soil respiration in wet years(2020)and weakened in dry years(2021).The results of structural equation model show that the change of soil respiration is related to belowground biomass.Shallow tillage and nutrient addition treatment had no significant effect on the temperature sensitivity of soil respiration,and nutrient addition plus shallow tillage treatment had no significant effect on the temperature sensitivity of soil respiration,but there were obvious inter-annual differences.In conclusion,the interannual precipitation should be considered to explore the effects of nutrient management and human disturbance on soil carbon flux in the agro-pastoral ecotone.