侵蚀环境人工刺槐林土壤水稳性团聚体演变及其养分效应

Dynamics of Soil Water-stable Aggregates in the Restoration Process of Artificial Robinia Pseudoacacia Under Erosion Environment

采用时空互代法,以典型侵蚀环境纸坊沟流域生态恢复过程中不同年限的人工刺槐林为研究对象,选取坡耕地和天然侧柏林为参照,分析了植被恢复过程中土壤水稳性团聚体变化规律及其与土壤养分状况之间的相互关系。结果表明,侵蚀环境下的坡耕地由于人为耕作干扰,土壤水稳性团聚体含量低下,抗蚀性能较差。营造刺槐林前5 a土壤水稳性团聚体含量较坡耕地显著快速增加,随后增幅变缓,成对数增长,恢复25 a后土壤水稳性团聚体含量已经达到天然侧柏林水平。在植被恢复过程中土壤小粒径的水稳性团聚体逐渐聚集转变形成大粒径的团聚体。相关性分析和回归分析表明,植被恢复过程中>0.25 mm土壤水稳性团聚体与有机碳、全氮、碱解氮、速效钾、容重等相关性达到显著(p<0.05)或极显著水平(p<0.01),与全磷和速效磷相关性较弱。坡耕地退耕营造刺槐林后可以减少人为干扰,增加碳素和氮素供给,提高水稳性团聚体含量,使土壤抗蚀性能提高。

In order to understand the dynamics of soil water-stable aggregates and the relationship with soil physico-chemical properties on abandoned arable land in the eroded hilly area of the Loess Plateau, 11 abandoned arable lands with different ages of Robinia pseudoacacia in Zhifanggou watershed were selected for a systematical study through the approach of substituting the temporal serial with spatial serial. In addition, the correlation between soil water-stable aggregates and physico-chemical properties were examined. Results showed that the content of soil water-stable aggregates increased promptly in the early abandoned stage, increased slowly with the extension of the abandonment, and then kept a relatively stable content in the following years. The content increased by 253. 45% in the first 10 year abandonment, but by only 16. 420/00 in the following 40 years. 〉0.25 mm aggregates were significantly correlated with soil organic carbon, total nitrogen, available P, CaCO3, and CEC, but not with total K and available K. It is necessary to close and manage hillsides, as well as keep soil organic carbon in a good balance in order to improve soil structure on abandoned arable land in the eroded hilly area of the Loess Plateau.