辽河口翅碱蓬湿地退化区土壤理化性质及生态阈值分析

为了研究不同退化程度下辽河口翅碱蓬湿地土壤理化性质的变化趋势及特征，找到翅碱蓬生长最适土壤环境指标的生态阈值，为辽河口区翅碱蓬湿地土壤生境保护和植被恢复提供参考，本研究以辽河口区翅碱蓬湿地为研究对象，在翅碱蓬湿地退化分区基础上，采用土壤理化性质实验法分析不同类型退化区土壤理化指标的变化趋势及特征，运用高斯模型测算翅碱蓬适宜环境的土壤因素生态阈值。结果表明:随着退化程度的增加，土壤含水量和有机质含量大致呈降低趋势。土壤砂粒含量逐渐增加，黏粒含量逐渐降低，土壤机械组成向粗大颗粒转化；土壤全盐含量呈大致增加的趋势；地表植被覆被逐渐减少，表层土壤受风和河水的侵蚀而流失，土壤中的碱解氮、有效磷、速效钾等营养元素也随之流失，土壤性状逐渐趋于恶化。在不同类型退化区内，土壤可溶性盐基阳离子含量特征均表现为Na+ > Ca2+ > K+ > Mg2+，土壤可溶性盐基阳离子以Na+为主；研究区土壤pH介于8.26 ~ 8.76之间，呈碱性。通过高斯模型测算出翅碱蓬生长最适土壤全盐含量的生态阈值为11.56 g kg?1，最适生态阈值区间为8.734 ~ 14.386 g kg?1，一般生态阈值区间为5.908 ~ 17.662 g kg?1；翅碱蓬生长最适土壤含水量生态阈值为47.5%，最适生态阈值区间为31.8% ~ 63.2%，一般生态阈值区间为16.1% ~ 78.9%。不同类型退化区由于水盐条件的差异对翅碱蓬生长的适宜程度不同，但可以通过灌溉水源、建立良好的灌排水系统等水盐调控方式，因地制宜，为湿地翅碱蓬生长提供理论和方法指导。

Soil Characteristics in Wetland Degradation Areas and Soil Threshold Calculation for Suaeda Salsa Growth in Liaohe Estuary Wetland

To figure out the ecological threshold of the most suitable soil environmental indices for the growth of Suaeda salsa, the changing trends and characteristics of soil physicochemical properties of Suaeda salsa wetland in Liaohe Estuary under different degradation levels were investigated, which would provide theoretical and methodological guidance for the soil habitat protection and vegetation restoration of the Suaeda Salsa wetland in the Liaohe Estuary. Based on the degraded zoning of Suaeda salsa wetland, the Suaeda salsa wetland in Liaohe Estuary wetland was taken as the research object to analyze the changing trends and soil physical and chemical characteristics in various degraded areas and assess the ecological thresholds of main soil indices in the most suitable environment for Suaeda salsa growth by using the Gaussian model. The results showed that with the increasing of the degradation degree, there were general downward trends in soil water content and organic matter content. Gradually, the soil sand content increased, while the clay content gradually decreased, indicating the soil mechanical composition was transformed into coarse particles. Total salt content generally increased. Moreover, the surface cover of vegetation gradually decreased, resulting in the surface soil eroded by wind and river water, and the soil nutrients such as alkaline nitrogen, available phosphorus, and available potassium were also lost. Soil properties gradually tended to deteriorate. In the different degraded areas, the characteristics of soil soluble base cations showed Na+ > Ca2+ > K+ > Mg2+, indicating that soil soluble base cations were mainly Na+. Soil pH in the study area was between 8.26 and 8.76, presenting alkaline. The optimal ecological threshold of soil total salt content for Suaeda salsa growth calculated by Gaussian model was 11.56 g kg?1 with a rang of 8.734-14.386 g kg?1, and the general ecological threshold range of that was 5.908-17.662 g kg?1. Moreover, the most suitable ecological threshold of soil water content for Suaeda salsa growth was 47.5% with a range of 31.8%-63.2%, and the general ecological threshold range of that was 16.1%-78.9%. Due to the difference in water and salt conditions, there was different suitability for the growth of Suaeda salsa in the different degraded areas. Even so, however, the water and salt control methods by regulating the irrigation water sources and the establishment of good irrigation and drainage system could be adapted to provide theoretical and methodological guidance for the growth of Suaeda salsa.