【摘要】 【目的】土壤水是淡水湿地森林生态系统水循环过程的关键环节。以江苏里下河地区的美洲黑杨（Populus deltoides）阔叶林和池杉（Taxodium distichum var. imbricatum）针叶林2种典型淡水湿地森林为研究对象，定量研究在3个不同量级降水条件下降水在林地土壤剖面中的运移过程，为揭示里下河地区淡水湿地森林对水文过程的调控作用提供科学依据。【方法】运用氢稳定同位素技术，通过分析比较3个不同量级降水后2种不同类型淡水湿地森林土壤水与其潜在水源（大气降水、浅层地下水）的δD组成，确定各林地土壤水的水分来源；运用二元线性混合模型计算不同量级降水对各层土壤水的贡献率。【结果】不同量级降水后8天内，2种类型淡水湿地森林土壤水δD值均介于大气降水δD和浅层地下水的δD值之间，表明该地区淡水湿地森林土壤水主要源于大气降水和浅层地下水；小雨（9.3 mm）后第1天，2个林地0～40 cm土层土壤水δD的变化范围较大，而40～60 cm土层土壤水δD变化范围较稳定，表明小雨仅能入渗到0～40 cm深处；而中雨（19.5 mm）及大雨（29.2 mm）后第1天，2个林地0～60 cm土层土壤水δD对降水δD的响应皆较明显，表明中雨和大雨均可入渗到0～60 cm深处土壤；此外，小雨、中雨和大雨对美洲黑杨阔叶林土壤水的贡献率分别为1.5%～33.5%、28.2%～66.4%和36.5%～97.0%，对池杉针叶林土壤水的贡献率分别为7.0%～37.4%、5.5%～48.2%和29.6%～75.0%。统计分析表明，降水量级是影响土壤水δD以及降水对土壤水贡献率的主要因子。【结论】里下河地区2种典型淡水湿地森林土壤水主要来源于大气降水和浅层地下水。单次降水量越大，土壤水δD对降水δD的响应越显著。池杉针叶林对小雨入渗补给过程的调控作用优于美洲黑杨阔叶林，而美洲黑杨阔叶林对大量级降雨（中雨和大雨）入渗补给过程的调控作用优于池杉针叶林。本研究结果可为今后我国长三角地区淡水湿地植被恢复过程中树种选择、湿地森林对水文过程的调控作用和水资源科学管理等提供科学依据。更多还原

【Abstract】 【Objective】Soil water is the crucial process of the water cycle in a freshwater wetland forest ecosystem. Two typical freshwater wetland forests(Populus deltoides forest and Taxodium distichum var. imbricatum forest) in Lixiahe area of Jiangsu province were selected as research objects for a quantitative study of the transport process of precipitation in soil profiles under different magnitudes of precipitation, consequently providing a scientific basis for revealing the regulation of freshwater wetland forest on the hydrological process in Lixiahe area. 【Method】We compared δD values in soil water and its potential water sources(precipitation, shallow groundwater) to determine the source of soil water using stable isotope technique in two types of freshwater wetland forests after different magnitudes of precipitation. Furthermore, we employed a binary linear mixed model to calculate the contribution rate of precipitation to soil water in each layer. 【Result】Within eight days after different magnitudes of precipitation,the δD values of soil water were between the range of both precipitation and shallow groundwater δD values, indicating that the soil water mainly derived from precipitation and shallow groundwater in freshwater wetland forests of the region. On the first day after the light rainfall event(9.3 mm), the more significant variation was in water δD values of 0～40 cm soil layer, while the relatively stable variation was in that of 40～60 cm soil layer, demonstrating that the 9.3 mm rainfall could only infiltrate to the depth of 0～40 cm.While on the first day after moderate(19.5 mm) and heavy rainfall events(29.2 mm), the apparent response occurred in soil water δD value of 0～60 cm soil layer to precipitation δD, stating that the two rainfall events could infiltrate into the depth of 0～60 cm.In addition, the contribution rates of light, moderate and heavy rainfall events to soil water in P. deltoides forest were 1.5%～33.5%,28.2%～66.4% and 36.5%～97.0%, respectively; and the contribution rates to the soil water of T. distichum var. imbricatum forest were 7.0%～37.4%, 5.5%～48.2% and 29.6%～75.0%, respectively. The magnitude of precipitation was the main factor affecting the δD value of soil water and the contribution rate of precipitation to soil water. 【Conclusion】The soil water mainly stems from precipitation and shallow groundwater in typical freshwater wetland forests of Lixiahe area. The larger the precipitation, the greater the response of soil water δD to precipitation δD. The contribution rates of different magnitudes of precipitation to the soil water in two forestlands showed that the regulation of the coniferous forest of T. distichum var. imbricatum to light rainfall infiltration is better than that of the broad-leaved forest of P. deltoides. In contrast, its regulations for moderate and heavy rainfalls infiltration are worse than that of the broad-leaved forest of P. deltoides. The research results can provide a scientific basis for tree species selection during wetland vegetation restoration, the regulation of wetland forests on the hydrological process, and scientific management of water resources in the Yangtze River Delta region in the future.更多还原