松嫩平原沙丘-草甸复合生态系统土壤水分和盐碱时空变化特征

在时间和空间尺度上,利用烘干法(105℃)、pH计和电导仪测定沙丘、草甸、沙丘和草甸结合部位,5—9月的0~300 cm土层土壤垂直剖面的土壤水分含量(SWC)、电导率(EC)和pH,来探究松嫩平原典型的沙丘-草甸复合生态系统中土壤水分和盐碱的时空分布特征。结果表明：不同部位平均土壤含水量存在极显著差异,草甸平均土壤含水量比结合部和沙丘分别高20.5%和52.7%。9月份结合部0~20 cm土层土壤含水量较高,而30~150 cm土层的土壤含水量较低。7月份草甸0~10 cm土层的平均土壤含水量较低,10~150 cm土层中平均土壤含水量随土壤深度增加而降低。不同部位的EC和pH也存在极显著差异,草甸区和结合部极显著高于沙丘,草甸的EC值比结合部高39.8%。7月份草甸0~10 cm土层和9月份30~70 cm土层有较高的EC和pH,9月结合部0~10 cm土层中有较高的EC和pH。土壤表面的盐碱化主要出现在7月和9月的草甸和结合部,而且两者盐碱化程度的不同主要是由物种、土壤和地下水位差异决定。

Spatiotemporal Variations of Soil Water and Saline-alkali in Compound Ecosystem of Sand and Meadow in the Songnen Plain

To explore the spatiotemporal variations of soil water and saline-alkali in compound ecosystem of sand and meadow in the Songnen Plain, the soil water content (SWC), electrical conductivity (EC), and pH in 0-300 cm soil profile in sand, meadow and middle area (between sand and meadow) regions from May to September were analyzed. The results showed that the mean SWC in meadow region was 20.5% and 52.7% higher (P<0.01) than that of middle area region and sand region, respectively. In middle area region, higher SWC in 0-20 cm soil and lower SWC in 30-150 cm soil were observed in September. In meadow region, SWC was lower in 0-10 cm soil in July and it gradually declined with the increase of soil depth from 10 to 150 cm. The mean EC and mean pH in meadow and middle area regions were higher (P<0.01) than that of sand region. The mean EC in meadow region was 39.8% higher (P<0.01) than that of middle area region. In meadow region, higher EC and pH were observed in 0-10 cm soil in July and in 30-70 cm soil in September. In middle area region, higher EC and pH were observed in 0-10 cm soil in September. The surface soil saline-alkali mainly occurred in meadow region and middle area region in July and September, respectively, and the different saline-alkali degree of the two kinds of regions was determined by species, soil texture and soil water table level.