不同养分添加对黄河源区退化高寒湿地土壤微生物碳源利用的影响

Effects of adding different nutrients on soil microbial carbon source utilization in degraded alpine wetland in the source region of the Yellow River

土壤微生物碳源利用能力是退化湿地修复过程中的重要评判指标,但在高寒退化湿地修复过程中,养分添加对土壤微生物碳源利用的影响仍不明确。为探究不同养分添加对黄河源区退化高寒湿地土壤微生物碳源利用能力的影响,本研究对黄河源区退化高寒湿地进行了氮、磷添加和有机掺混肥添加处理,采用常规实验室分析法和Biolog-Eco法,分析了不同养分添加处理对湿地不同退化阶段植被特征、土壤理化性质和土壤微生物碳源利用的影响。结果表明:氮添加可以显著提高中度退化阶段土壤微生物碳源利用能力,磷添加和有机掺混肥添加后退化湿地土壤微生物碳源利用能力没有显著提高。不同养分添加处理可以影响土壤微生物对不同种类碳源的利用能力,其中氮添加和有机掺混肥添加可以提高退化湿地土壤微生物脂类和醇类碳源的利用占比,降低酸类碳源的利用占比。不同养分添加下退化高寒湿地土壤微生物总体碳源利用能力主要取决于土壤微生物对酯类、醇类和胺类碳源的利用。结构方程模型分析显示,退化高寒湿地氮添加和有机掺混肥添加都可以通过提升植被地上生物量促进土壤微生物碳源利用,但有机掺混肥对土壤微生物碳源利用的提升作用受土壤水分含量降低的限制。该结果可为高寒退化湿地修复技术研发和退化高寒湿地修复效果评判提供科学依据。

The carbon source utilization capacity of soil microbes is an important evaluation indicator during the restoration of degraded wetlands.However,the effects of nutrient addition on carbon source utilization of soil microbes during the restoration of degraded wetlands remains unclear.The aim of this study,therefore,was to determine the effect of adding different nutrients on the carbon source utilization ability of soil microbes in a degraded alpine wetland.To this end,a field experiment was conducted in degraded alpine wetlands at various stages of degradation in the source region of the Yellow River.Nitrogen,phosphorus,and organic compound fertilizer were added to the soil,and the effects of these treatments on the vegetation characteristics,soil physicochemical properties,and carbon source utilization of soil microbes in wetlands at different stages of degradation were analyzed using conventional laboratory methods and the Biolog-Eco method.The results indicate that nutrient addition significantly improved the overall carbon source utilization ability of soil microbes in moderately degraded alpine wetland.However,the carbon source utilization ability of soil microbes in more heavily degraded wetland was not significantly improved by adding phosphorous or organic compound fertilizer.The addition of different nutrients affected the ability of soil microbes to utilize different carbon sources.In degraded wetland,the addition of nitrogen and organic compound fertilizer significantly increased the proportion of lipid and alcohol carbon sources utilized by microbes,and decreased the proportion of acid carbon sources utilized.After the addition of different nutrients,the overall carbon source utilization ability of soil microbes in the degraded alpine wetlands was mainly influenced by their ability to utilize esters,alcohols,and amino acids.Structural equation modeling showed that the addition of both nitrogen and organic compound fertilizer promoted the carbon source utilization of soil microbes by increasing the aboveground biomass of vegetation in degraded alpine wetland.However,the effect of adding organic compound fertilizer to enhance carbon source utilization by microbes was limited by lower soil moisture contents.These results provide a scientific basis for further research on,and development of,restoration strategies for degraded alpine wetlands and for the evaluation of the extent of restoration.