关键词: 淡水湿地森林, 氘同位素, 降水, 土壤水, 浙江绍兴

Abstract: [Objective] Three different types of freshwater wetland forests (broad-leaved forests, coniferous-broad-leaved mixed forests, and coniferous forests)were selected as research objects to analyze the temporal and spatial variations of deuterium isotope values in forest soil profiles after different magnitude precipitation,and quantitatively explain the contribution of precipitation to the soil water in each layer in Tangpu Reservoir Area of Shaoxing, Zhejiang Province. The result of this study provide a scientific basis for revealing the distribution of precipitation in the water cycle of forest ecosystems in the wetlands of the area.[Method] In this study, we examined the dynamic variation of deuterium values (δD) in Soil Waterby using stable isotope technique under three different rainfall conditions inthree different types of freshwater wetland forests, analyzed the relationship of δD values between soil water and the potential water sources (rainfall and shallow underground water, etc.), and further determined the source of litter water and soil water and the distribution of one-timerainfall in the three wetland forests. The contribution rate of rainfall in litter and each layer of the soil profile was calculated according tobinary linear mixed model after the occurrence of different rainfall events.[Result] The δD values of soil water were between those δD values of rainfall and shallow groundwater after three different magnitudes ofrainfall in the freshwater wetland forests in the Tangpu Reservoir Area of Shaoxing, indicating that the soil water and litter water mainly came from precipitation and shallow groundwater.After small rainfall (7.5 mm), the soil water δD values in 0-60 cm increased slightly and were higher than the values before rain, however, there was almost no change and relatively stable in the δD values of 60-100 cm deep soil water, indicating that 7.5 mm precipitation could be infiltrated and recharged into the 60 cm soil layer in the three wetland forests. The first day after moderate rain (14.5 mm), the soil water δD average values of the soil layer of 0-100 cm decreased by 9.5‰±4.0‰, 9.3‰±4.1‰, and 7.0‰±2.6‰ in the broad-leaved,mixed broadleaf-conifer, and coniferous forests, respectively. In 9 days after the moderate rainfall, the soil water δD value of the three forests kept changing with increasing number of days after rainfall and approached to control before rain, indicating that the effect of precipitation δD on soil δD gradually decreased.The first day after the heavy rain (35.0 mm),δD value of the litter water and surface soil layer of 0-20 cm in the three forests was close to rainfall δD value. The contribution rate of rainfall to the litter layer in the three forests was the highest, and the contribution rate to soil water was the second at soil layer of 0-20 cm.With the increase of sampling days, the contribution of precipitation to the soil water in each layer was presented with a decreasing trend.Precipitation events (precipitation of different magnitudes)were the main factors affecting the soil water δD and the contribution of precipitation to soil water after rain.[Conclusion] The response of δD values of litter layer to precipitation was the most significant, soil water δD (0-20 cm) to rainfall δD was second significant in the wetland forests of Tangpu Reservoir Area in Shaoxing, Zhejiang Province.The greater magnitude of one-time rainfall, the more obvious the effect on soil water (0-100 cm), and the greater the rainfall contribution to the soil water,heavy rain (precipitation>20 mm) affected soil water in each layer for more than 9 days. The result suggest that freshwater wetland forest played an important role in regulating the process of small rainfall (precipitation ≤ 10 mm) and moderate rainfall(10 mm

Key words: freshwater wetland forests, deuterium isotope, rainfall, soil water, Shaoxing, Zhejiang Province