科尔沁沙地黄柳灌丛降雨截留与再分配特征

2012年5-9月,通过对科尔沁沙地典型沙生灌木——黄柳灌丛对降雨再分配过程的野外观测,确定了穿透雨量(TF)、树干茎流量(SF)和冠层截留量(I)在降雨过程中的分配比例,并分析了降雨量(P)和降雨强度(RI)对冠层截留过程和降雨再分配的影响。试验期间,完整观测到穿透雨和树干茎流的降雨共20次,降雨量共为135.32 mm,其中TF、SF和I分别为(112.01±5.77) mm,(2.96±0.03) mm和(20.35±5.74) mm,占总降雨量的百分比分别为82.78%,2.19%和15.03%。回归分析表明,分别用二次函数、幂函数和“S”型曲线拟合TF、SF和I与P的关系较好(P<0.001),TF、SF和I均随降雨量的增加而增加,但I存在1个上限(1.40 mm),I随降雨量的增加无限趋近于1.40 mm;TF%、SF%和I%与P的关系分别可以用对数函数、幂函数和指数函数拟合(P<0.001),TF%和SF%随降雨量的增加而增加,I%反之;I%随RI的增大呈逐渐减小的趋势,SF%随RI的增大呈先增大后减小的趋势;5-9月灌丛截留率呈先增大后减小趋势,连续性降雨减小冠层的截留率,更利于树干茎流的形成。

Characteristics of rainfall interception and redistribution for Salix gordejevii in Horqin Sandy Land,Northeast China

This study aimed to clarify the characteristics of rainfall redistribution in desert shrub areas and the relationship between interception, stemflow and rainfall characteristics (precipitation and rainfall intensity). From May 30 to September 3, 2012, a field experiment was conducted to investigate rainfall redistribution in Salix gordejevii shrub which is one of the typical psammophytes in Horqin Sandy Land, Northeast China. During the experimental period, there were 20 rainfall events, and the cumulative gross rainfall was 135.32 mm. The amounts of throughfall (TF), stemflow (SF) and interception (I) were (112.01±3.76) mm, (1.97±0.20) mm, and (21.33±3.74) mm, respectively, and the proportions of TF, SF and I were 82.78%, 2.19% and 15.03%, respectively. Statistical analysis showed that the correlations between precipitation with TF, SF and I could be fitted by quadratic function, power function and “S” curve, respectively (all P<0.001). TF, SF and I all increased with precipitation increase, but there was an upper limit (1.40 mm) for I. The relationships between precipitation with TF%, SF% and I% might be presented by a logarithmic function, power function and exponential function, respectively (all P<0.001). TF% and SF% increased with a precipitation increase while I% decreased. Moreover, I% decreased with an increased rain intensity, while SF% increased initially then decreased. I% first increased then decreased from May to September, indicating there was an optimum rainfall intensity for SF. Continuous rainfall lowered I%, and raised SF%.