漓江河岸带不同水文环境土壤微生物与土壤养分的耦合关系

基于漓江河岸带典型地段内砾石滩、草地、灌草地和疏林地等4类水文环境梯度上的土壤样品分析,探讨了漓江河岸带土壤养分、微生物数量及微生物量等的变化特征及耦合关系。结果表明:土壤养分含量、土壤微生物数量及微生物量等在不同水文环境下均有显著差异。随着水淹时间的减少,土壤含水量、pH值、有效氮、有效磷和有效钾均呈先增后减的趋势,最大值多出现在灌草地,最小值多出现在砾石滩,而土壤微生物总量、细菌、放线菌数量和微生物量也为先增后减趋势,其数量或含量在灌草地最多,砾石滩最少。简单相关分析表明漓江河岸带各微生物指标与土壤有效氮、有效磷及速效钾相关性较强,与土壤全氮、全磷和全钾的相关性较弱。冗余分析表明土壤有效氮、有效磷和含水量是影响微生物总数、细菌数量、微生物量碳、微生物量氮和微生物量磷的重要因素,而有机质和全氮是影响放线菌数量的重要因素。研究结果说明适当的水文干扰有利于河岸带土壤养分的积累,对土壤微生物数量及其生物量也有显著促进作用;土壤有机质和有效养分含量(有效氮、有效磷等)与微生物数量及微生物量关系密切,其含量很大程度影响着微生物数量及其活性。在漓江河岸带生态保护和评估等研究过程中应充分考虑不同水文环境下的土壤微生物和养分的变化特征及耦合关系。

Coupling relationships between soil microbes and soil nutrients under different hydrologic conditions in the riparian zone of the Lijiang River

Based on the analysis of soil samples in four different hydrologic conditions of the Lijiang Riparian Zone, i.e., gravel zone, grass zone, shrub-grass zone, and tree zone, this study explored the variation characteristics and relationships among soil nutrients, microbe quantity, and microbial biomass. The results showed significant differences in soil nutrients and microbes among various hydrologic conditions. As the submersion duration decreased, the value of soil water content (SWC), pH, available nitrogen (AN), available phosphorus (AP), and available potassium (AK) increased and then decreased, the highest value usually appeared in the shrub-grass zone, whereas the lowest was in the gravel zone. The total amount of soil microbes, bacteria, actinomycetes, and microbial biomass carbon, nitrogen, and phosphorus (MBC, MBN, MBP) also exhibited an increasing-decreasing trend, and reached a maximum in the shrub-grass zone and a minimum in the gravel zone. Simple correlation analysis showed that various indexes of microorganisms were closely related to AN, AP, and AK and had a loose relationship with total nitrogen (TN), total phosphorus (TP), and total potassium (TK). Redundancy analysis revealed that AN, AP, and SWC were important factors affecting the total amount of microbe, bacteria, and microbial biomass C, N, and P, and soil organic matter (SOM) and TN were important factors affecting the amount of actinomycetes. The above results suggested that appropriate hydrologic disturbance was beneficial to the soil nutrient accumulation, and also had a positive impact on the soil microbes and their biomass. The SOM and available nutrients (AN, AP) were closed to soil microbes, and their contents greatly affected the quantity and activity of soil microbes. In the research process of ecological protection and assessment of the Lijiang riparian zone, the variation characteristics and relationship between soil microbes and nutrients under different hydrological conditions must be considered.