南方红壤丘陵区杜仲人工林土壤水分动态

利用时域反射仪(TDR)定位监测方法,研究了南方红壤丘陵区杜仲人工林土壤水分分配规律.结果表明:不同月份间土壤蓄水量差异极显著(P<0.01),研究时段内土壤水分呈低-高-低的单峰变化.杜仲人工林土壤水分垂直变化显著,且不同季节变化规律各异:根据土壤水分的季节消长和物候变化趋势可将土壤水分变化分为土壤水分积累期和消耗期;按降雨量的季节分配可将土壤水分变化分为干季和湿季两个时段.土壤蓄水量与大气相对湿度(RH)、大气温度(t)、饱和水汽压差(VPD)、降雨量(R)显著相关(P<0.05),降雨量是最直接的影响因子,其次是大气温度.次降雨后土壤水分损失率与干旱天数呈显著的双曲函数关系(P<0.05),土壤蓄水量与雨后干旱天数呈显著线性负相关(P<0.05),在次降雨后的持续干旱条件下,土壤水分损失随着土层深度的增加逐渐趋于缓和.

Dynamics of soil water under Eucommia ulmodes plantation in hilly red soil region of southern China

By using time domain reflectometry(TDR),a fixed-position monitoring research on the dynamics of soil water under Eucommia ulmoides plantation was conducted in a hilly red soil region of southern China.The results showed that there was a significant difference in the soil water storage among different months,and the dynamics of soil water could be divided into the phases of reduction,increase,and more reduction.Soil water varied significantly in its vertical distribution,and the variation pattern also differed with seasons.The vertical distribution of soil water could be divided into two phases,i.e.,accumulation and depletion based on the seasonal variation of soil water,or rainy season and dry season based on the monthly variation of rainfall.Soil water was correlated significantly(P<0.05)with relative humidity(RH),air temperature(t),vapor pressure deficit(VPD)and rainfall(R),and regulated by these meteorological factors synthetically,among which,rainfall was the most important factor,followed by air temperature.The soil water loss rate after rain had a significant hyperbolic relationship with durative droughty days,while soil water storage had a significant linear negative relationship with this duration(P<0.05).With the extension of drought duration after rain,soil water loss tended to vary gently with increasing soil depth.