Characteristics of water circulation and balance of typical vegetations at plot scale on the Loess plateau of China

Large-scale artificial afforestation has aggravated the water scarcity and resulted in the severe soil desiccation in the Loess plateau of China. Understanding the water circulation processes and the water balance characteristics of typical vegetations is of great significance to the vegetation restoration in the Loess plateau of China. Based on field observation from May to October in 2004, the soil desiccation under five vegetations was investigated in the Liudaogou watershed on the Loess plateau of China. Moreover, the water circulation and balance of them at plot scale were also studied. The results showed that among these five vegetations, the degree of soil desiccation under alfalfa and caragana was more severe than that under defarming grassland, millet and soybean, and there existed the dried soil layers under caragana and alfalfa. The dynamic of the soil water storage under five vegetations was quite similar and the soil water storage in the five runoff plots followed the order: defarming grass > millet > soybean > caragana > alfalfa. The order of runoff amount in the five plots was soybean > millet > defarming grass > alfalfa > caragana. The water consumption (ET) of five vegetations followed the order: caragana > alfalfa > defarming grass > soybean > millet. The results indicated that the greater the evapotranspiration of one vegetation, the higher the possibility to develop the soil desiccation under it. The findings provided helpful reference for the vegetation restoration and environment improvement programs in the Loess plateau of China.