黄河下游典型湿地土壤养分及其生态化学计量特征

土壤中碳氮磷钾是植物生长发育所需的必要养分元素，其含量和生态化学计量比能够反映土壤质量与养分限制状况.选取黄河下游河南段的花园口黄河浮桥湿地为研究对象，运用方差分析、冗余分析和线性回归拟合等研究方法，分析黄河下游典型湿地土壤有机碳（SOC）、全氮（TN）、全磷（TP）、全钾（TK）、碱解氮（AN）、速效磷（AP）、速效钾（AK）及其生态化学计量特征，明确土壤养分的限制性元素，揭示影响湿地土壤养分及其生态化学计量比的关键理化因子.结果表明，湿地土壤ω（SOC）、ω（TN）、ω（TP）、ω（TK）、ω（AN）、ω（AP）和ω（AK）的均值分别为： 5.46 g·kg^-1、0.60 g·kg^-1、0.28 g·kg^-1、17.06 g·kg^-1、13.75 mg·kg^-1、6.54 mg·kg^-1和158.56 mg·kg^-1，其空间分布呈现出从河岸向滩地波动增加的变化趋势，高植被盖度区普遍高于低植被盖度区，且土壤SOC、TN、TP和TK之间具有较强的相关性；土壤C/P、C/K、N/P和N/K呈现出和土壤养分一致的变化趋势，而C/N则相反；土壤SOC、TN、AN、N/P和N/K变异系数超过50.00%，其空间差异性较强；湿地土壤C/N均值为11.882，接近中国土壤均值，而C/P和N/P的均值分别为49.119和4.516，两者均低于中国土壤平均水平，并且土壤N/P远小于14，研究区土壤受N限制；土壤黏粒占比和电导率共同解释了土壤养分变异与其生态化学计量比变异的61.4%和43.9%，是影响花园口黄河浮桥湿地土壤养分和生态化学计量比的主要理化因子.研究结果有助于加深对黄河下游湿地土壤养分及其影响因素的认知，为黄河下游湿地生态修复与管理提供重要科学依据.

Nutrients and Ecological Stoichiometry Characteristics of Typical Wetland Soils in the Lower Yellow River

Carbon, nitrogen, phosphorus, and potassium in the soil are the necessary nutrient elements for plant growth, and their contents and ecological stoichiometry can reflect the status of soil quality and nutrient limitation. The Huayuankou Yellow River Floating Bridge Wetland in the lower Yellow River was selected as the research object. The methods of ANOVA, redundancy analysis, and linear regression fitting were used to study the contents of organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), total potassium (TK), alkaline nitrogen (AN), available phosphorus (AP), available potassium (AK), and their ecological stoichiometric ratios as well as the limiting elements of soil nutrients, and the key physicochemical properties that affect soil nutrients and their ecological stoichiometry in the wetland were revealed. The results showed that the mean values of ω(SOC), ω(TN), ω(TP), ω(TK), ω(AN), ω(AP), and ω(AK) in wetland soil were 5.46 g·kg^-1, 0.60 g·kg^-1, 0.28 g·kg^-1, 17.06 g·kg^-1, 13.75 mg·kg^-1, 6.54 mg·kg^-1, and 158.56 mg·kg^-1, respectively, which showed an increasing trend from the river bank to the shoaly land and were generally higher at the high vegetation coverage areas than at the low vegetation coverage areas. There were significant correlations among SOC, TN, TP, and TK. Soil C/P, C/K, N/P, and N/K showed a consistent trend with soil nutrients, whereas C/N showed the opposite. The coefficients of variation of SOC, TN, AN, N/P, and N/K in the soil exceeded 50.00%, with significant spatial differences. The average value of C/N in wetland soil was 11.882, which was close to the average level of soils in China, whereas the average values of C/P and N/P were 49.119 and 4.516, respectively, both of which were lower than the average level of soils in China, and the N/P of soil was far less than 14, which indicated that N was limited in the soil. The proportion of clay and electrical conductivity combined to explain 61.4% and 43.9% of the variation in the soil nutrients and their ecological stoichiometry, respectively, which were the dominant soil physicochemical properties affecting the soil nutrients and their ecological stoichiometry of Huayuankou Yellow River Floating Bridge Wetland. The research results are helpful to improve our knowledge of nutrients and their influencing factors in the wetland soil of the lower Yellow River and provide an important scientific basis for the ecological restoration and management of the wetland in the lower Yellow River.