咸水滴灌下林带的盐结皮时空分布规律

Spatiotemporal Distribution of Salt Crust in a Shelter-forest Belt under Dripirrigation with Salt Water

通过对塔里木沙漠公路防护林带地表土壤的采样分析,研究了咸水滴灌条件下,土壤盐结皮的时空分布特征。厚度、电导率是盐结皮的主要特征参数,它们的时空变化可以表征盐结皮的分布。盐结皮的主要时空分布特征:①在水平方向上,电导率呈先增加后降低的变化趋势,厚度在距滴头40 cm处达最大,而在40 cm以外变化不明显;②在坡地上,滴头的上坡向盐结皮的厚度和电导率大于下坡向;③随着防护林种植年限的增长,盐结皮厚度逐渐增加,并最终保持在某一稳定厚度,而电导率则呈先增加后逐渐降低的趋势。

The Takilimakan Desert is the largest desert in China, and its area is 3.37 × 10^5 km^2. In the desert it belongs to the extremely arid temperate continental climate, the annual temperature and precipitation are 12.4℃ and 11.1 mm respectively, but the annual evaporation is as high as 3 638.6 ram. The shelter-forests, 436 km in length and 72-78 m in width, are planted along the Takilimakan Desert Highway. By collecting and analyzing the soil samples, in this paper the spatiotemporal distribution of surface salt crust in the shelter forest belts under drip-irrigated with salt water in the hinterland of the Takilimakan Desert is lucubrated. Thickness and electric conductivity （EC） are the main characteristic parameters of salt crust, and their spatiotemporal change can be used to characterize the distribution of salt crust. The spatiotemporal distribution features of salt crust are as follows： （1） Horizontally, the EC of salt crust increases at first, and then decreases with the increase of distance away from drippers; the thickness of salt crust changes significantly within a range of 40 cm from drippers, but changes slightly further away from this range, and the maximum thickness of salt crust occurs at the place 40 cm away from drippers; （2） The micro-relief has a great effect on the spatial distribution of salt crust; on a slope, the thickness and EC of salt crust on upgrade of drippers are higher than that on downgrade; （3） The thickness of salt crust increases with the increase of age of shelter-forests at early stage, and then it tends gradually to a steady value; the EC of salt crust increases at the early stage of shelter-forests, and then it decreases gradually.