南疆主要地表类型土壤风蚀对形成沙尘暴天气的影响

Soil Erosion of the Main Ground Surface Types Influences on Formation of Dust Storm in South Xinjiang

【目的】弄清南疆主要地表类型土壤风蚀对形成沙尘暴天气的影响,为明确该区域沙尘暴主要尘源和科学治理提供依据。【方法】采用美国BSNE集沙仪,在沙尘暴天气条件下对塔里木盆地主要地表类型土壤风蚀状况、输沙率随高度的变化进行观测与采样分析。【结果】不同地表类型的输沙量变化趋势为:裸露、弃耕农田最多,其次为活化灌丛沙堆、沙漠边缘的活动沙丘、乡村道路;而封育砂质农田、覆膜棉田、苜蓿地、冬小麦、棉秆与地膜相间覆盖棉田、林地、棉秆留茬地输沙量较少。种植行向与风向一致时棉田输沙量大,垂直时明显减少。输沙量在0～160cm高度的分布特征明显与地表类型有关,其中裸露、弃耕农田、活化灌丛沙堆、活动沙丘等植被、残茬覆盖地表类型,输沙量(M,g·cm-2)随高度(Z,cm)变化遵循幂函数M=aZb规律,在有植被及覆盖条件下的农田、林地等地表,输沙量用多项式M=a+bZ+cZ2+dZ3拟合效果最好。输沙量随植被覆盖度和土壤表层含水量的增加呈指数形式减少,当植被盖度达到20%以上或土壤表层含水量达到5%以上时可以明显降低输沙量。【结论】裸露农田、弃耕沙质农田、活化灌丛沙堆、活动沙丘以及乡村道路的风蚀程度严重,是南疆沙尘暴天气沙尘的主要来源。在农区,扩大冬小麦、多年生牧草等冬春绿色覆盖作物种植,实行保护性耕作制;在绿洲与沙漠过渡带,采取禁止放牧及合理开垦,实行天然封育和弃耕地改造;对乡村道路实现硬化,是南疆控制土壤风蚀、减少沙尘暴沙尘源的重要途径。

[ Objective ] The objective of this paper is to study the effect of soil wind erosion of the mainground surface types on formation of dust storm in South Xinjiang as Tarim Basin is one of the areas of high-incidience sand strom and the main sand-sources place in China. [Method] Using U.S.A. BSNE sandy samplers, the main surface types and the amount of sand transport with changing height under the sandstorm weather condition in South Xinjiang were observed and analyzed. [Result] The results indicate that the order of amount of sand transport on different types of surface is： bare and abandoned farmland, sand heaps of activated shurub clusters, the active sand dunes on the edge of the desert, the rural roads. The amounts of sand transport are little in the seal sandy farmland, cottons covered the film, alfalfa fields, winter wheat, cotton covered stalk and film, the forest land and cotton stalks inside the stubble fields. The amounts of sand transport are more in cottons covered with film paralleling with wind direction than being vertical. The amounts of sand transport in 0-160 cm height obviously relate to types of the surface. The amounts of sand transport （M, g·cm^-2 ） follow the regular changes of exponential function M =aZ^b with height （Z, cm ） on the bare ground, abandon farmland, sand heaps of activate clusters, the active sand dunes on the edge of the desert, which have no or few vegetation coverage. Best fit results were obtained by using the multinomial M = a ＋bZ ＋cZ^2 ＋dZ^3 in fields with vegetation coverage, forest land, etc. Wind erosion amount reduced exponentially with the increase of vegetation cover degree and water content of soil top layer. When vegetation degree is more than 20% or water content of soil top layer more than 5% can obviously reduce the amount of sand transport. [ Conclusion ] There are serious wind erosion in bare farmland, abandoned sandy farmland, sand heaps of activated clusters, active sand dune and rural road, which are also main dust sources of the sandstorm in South Xinjiang. Some measures should be adopted to control the soil wind erosion and reduce sandstorm dust and sand source in South Xinjiang, such as expanding the cultivated area of winter wheat, planting perennial grass and green crops, etc, implementing the protective cultivation system, avoiding over-grazing and cultivating rationally on the intermediate zone, sealing and breeding naturally, abandoning and transforming the cultivated land and hardening the rural roads etc. rational cultivation on the intermediate zone, and practicing natural sealing and breeding.