沙漠水渠人工固沙区沙篙和沙拐枣灌丛的土壤水分特征对比

摘要

The natural Artemisia arenaria and Calligonum mongolicunl shrubs were selected in five-year sand fixation area beside the desert canal in Gurbantunggut Desert , Northwest China . According to shrub crown size , five horizontal distance levels and four vertical depth levels were chosen to contrastively study the soil water content (SWC ) of the two shrubs . The result showed that the SWC values increased with the soil layer depth , the AWC values of two lower lay- ers (20~40 cm , 40~60 cm) were significantly (P<0 .05) more than the two upper layers (0~10 cm, 10~20 cm) , while the other AWC were not markedly different . There were no clear differences at every distance at the soil layers of the two upper levels of A . Arenaria shrub and total four of C. Mongolicunl shrub . While the RWC of mid-shrub (50 cm ) at the two lower layers of A . Arenaria were the most, and it was significantly ( P<0 .05 ) different from the shrub edge (80 cm). The soil bulk density values at the upper layers of the two shrubs were slightly higher than those at the two lower layers , but there were no evident differences between the two shrubs , different distances and different layers . It was found that A . Arenaria shrub with dense branches had a certain "fertile island effect" of water , compared to C . Mongolicunl shrub which had sparse branches . This effect was beneficial to the growth and diffusion of A . Arenaria population , maybe it was one of the important factors to cause the distribution difference of the two shrubs and to widely dis- tribute in the artificial sand-fixation area for A . Arenaria population .%在古尔班通古特沙漠引水渠沿线建植5a的人工固沙区内,选择自然生长的沙蒿和沙拐枣灌丛,依据冠幅大小设置5个水平距离梯度和4个土层深度梯度.对比研究了二者的土壤水分特征.结果表明,随土层深度的增加,两种灌丛土壤含水量均呈增加趋.,中下部2层(20～40 cm和40～60 cm)土壤含水量显著(P<0.05)高于上部2层(0～10 cm和10～20 cm),其他各层间差异不显著.在沙蒿灌丛上部2个土层、沙拐枣灌丛全部4个土层上,不同距离间的土壤含水量无显著差异;但沙蒿灌丛下部2个土层的中环区(50 cm)土壤含水量最高,显著(P< 0.05)高于灌丛边缘(80 cm).两种灌丛上部2层土壤容重稍高于下部2层,但灌丛间、不同距离和不同土层间差异均不显著.研究发现,相比于稀疏分枝的沙拐枣灌丛,分枝稠密的沙蒿灌丛表现出一定的水分"沃岛效应",有利于沙蒿种群的生长和扩散,这可能是造成二者分布差异及沙蒿种群大面积分布于人工固沙区的重要原因之一.