南方丘陵区不同坡地利用方式土壤水分动态

土壤水分异质性的存在对各种水文过程和土壤形成过程均有显著的影响,了解土壤水分的异质性对理解和预测土壤水分过程具有重要意义.应用时域反射仪(TDR)土壤水分定位监测方法,研究了南方丘陵区不同坡地利用方式土壤水分动态及其影响因子.结果表明:3种坡地利用方式土壤水分变化具有明显的季节特征,杜仲人工林土壤蓄水量最高,荒山草坡次之,坡耕地最低.植物非生长季节土壤含水量均值高于生长季节,生长季节土壤水分消耗大于补给,非生长季节土壤水分补给大于消耗;干季和湿季两个时段3种坡地利用方式土壤含水量垂直变化趋势具有相似性,其土壤含水量差异不显著.3种坡地利用方式土壤蓄水量与太阳辐射量和大气温度表现为负相关性,与降雨量、大气相对湿度和饱和水气压差表现为正相关性,降雨量是其最直接的影响因子,其次是温度.雨季单次降雨后土壤蓄水量与雨后干旱天数存在显著的线性负相关性(P<0.05),土壤水分损失率与干旱天数存在双曲函数关系(P<0.05), 随着干旱天数的增加,土壤水分损失率趋于平缓.雨季单次降雨后持续干旱条件下3种坡地利用方式土壤剖面含水量呈递减的变化趋势,杜仲人工林土壤水分损失率系数最高,荒山草坡次之,坡耕地最低.

Spatial and temporal dynamics in soil water storage under different use types of sloping fields: a case study in a highland region of southern China

Soil water heterogeneity has significant effects on many hydrological processes and soil development processes, and research on spatial and temporal heterogeneity in soil water content is important for understanding and forecasting soil water processes. In situ monitoring of soil water content changes in sloping fields under different use types were carried out in a highland region of southern China using time domain reflectometry (TDR). There was a significant variation in soil water storage among sloping fields under different use types, and soil water storage under Eucommia ulmoides plantation was found to be the highest, followed by non-cultivated sloping field and the lowest by cultivated sloping field. There was also a significant seasonal variation in soil water storage, with the average soil water content being higher during the non-growing season than during the growing season. In addition, there was a similar pattern of change in soil water profiles under different types of sloping field use in either wet or dry seasons. A negative relationship was observed between soil water storage and solar radiation and air temperature, but there was a positive relationship of soil water storage with rainfall, relative humidity and vapor pressure deficit. Thus, we can predict that soil moisture was strongly influenced by a combination of several meteorological factors, among which the most important factor was precipitation and the next important factor was temperature. After rain, soil water loss rate of the three sloping field types had a significant hyperbolic relationship with drought durating days (P<0.05), but soil water storage had a significant negative linear relationship with drought durating days (P<0.05). Furthermore, soil water loss was found to vary with the period of drought duration as well as with soil depth.