黄土高原撂荒川地植被演替及土壤性质分析

The vegetation succession and soil properties of abandoned valley land in the Loess Plateau

以土壤含水量较高的陕北黄土高原撂荒川地为对象,研究了撂荒2年、4年、6年川地的植被演替、土壤理化变化状况以及土壤酶活性。结果表明:土壤含水量达到8%以上,撂荒地植被演替沿低级向高级发展。从以沙芦草(Agropyron mongolicum)、猪毛菜(Salsola collina)等为优势种喜阳小型草本群落,逐渐演替为以柽柳(Tamarix chinensis)、菖蒲(Acorus calamus)、芦苇(Phragmites)为优势种的中、湿生大型草本和灌木混合群落。撂荒后土壤浅层物理结构呈现先下降、后逐渐上升的趋势,深层物理结构随时间推移变化不大;土壤浅层的有机质、碱解氮等养分含量也呈现先下降、逐渐升高的趋势。撂荒6年土壤碱性磷酸酶、蔗糖酶含量相对在耕地分别上升424.7%、141.7%。在黄土高原撂荒川地土壤水分状况较好的条件下,次生裸地采用避免人工干预、自然恢复的方式,植被生态系统会由低级向高级发展,土壤理化结构、酶活性也向有益的方向发展。

Taking the higher moisture abandoned valley land in the Loess Plateau, Northern Shaanxi, as tested object, the vegetation succession, soil physicochemical changes and soil enzyme activity were studied in the abandoned 2 years, 4 years, 6 years valley land. The results showed that the water content in soil reached more than 8 %, the rule of vegetation succession was from low level to high level development. Agropyron mongolicum, Salsola collina were dominant species in heliad small herbaceous community, Tamarix chinensis, Acorus calamus, Phragmites were the dominant species in wetland herbs and shrubs mixed with large fall. The physical structure of the shallow soil layer after abandonment showed a dowoward trend first and then gradually upward trend. There were no changes with time in the deep soil physical structure. Shallow soil organic matter, available nutrients such as N also showed a decline first, gradually increased trend. The content of AKP, Sucrase in the abandoned 6 years land increased by 424.7%, 141.7% compared with the cultivated land. In the way of natural restoration without manual intervention for the condition of higher soil moisture abandoned valley land in the Loess Plateau, the vegetation ecosystem would evolve from low-grade to high-grade, the soil structure, enzyme activity were beneficial to the direction of development.