Change of soil anti-erodibility of artificial shrubs in loess hilly area | 黄土丘陵区人工灌木林土壤抗蚀性演变特征

Chinese. 【目的】土壤抗蚀性是评定土壤抵抗土壤侵蚀能力的重要参数之一,研究黄土丘陵区坡耕地退耕营造灌木林后土壤抗蚀性变化过程对认识该地区生态恢复过程中土壤质量的演变及其效果评价具有重要意义。【方法】采用时空互代法,以黄土丘陵区不同年限的人工灌木林为研究对象,选取坡耕地和天然侧柏林为对照,通过室内测试分析,并运用统计和相关分析等方法,研究土壤抗蚀性的变化过程。【结果】侵蚀环境下的坡耕地由于受到人为活动的干扰,土壤抗蚀性能低下,种植灌木林后,土壤抗蚀性显著提高。其中土壤水稳性团聚体含量逐渐增加,并从小粒径为主改变为大粒径占绝对优势,平均重量直径(EMWD )随种植年限逐渐上升,结构体破坏率逐渐降低;微团粒结构随种植年限从小粒径向大粒径转变,有机质含量、土壤团聚状况、团聚度和分散系数均呈增加趋势;总体来看相同年限的沙棘林对土壤抗蚀性改善作用强于柠条林。相关性分析显示,土壤抗蚀性指数(SAI)、团聚状况、团聚度、微团聚体和土壤理化性质相关性较高,可以作为反映土壤质量中的抗蚀性指标。黄土丘陵区坡耕地SAI极其低下,退耕营造柠条林后,SAI显著增加,25年时较坡耕地增加497%,为相同年限沙棘林的69%,天然侧柏林的52%。【结论】黄土丘陵区坡耕地人为干扰是造成土壤抗蚀性降低的主要原因,营造灌木林后可以显著改善土壤抗蚀性能,但是与该地区顶级群落时的土壤抗蚀性相比,还存在着较大差距,SAI可以有效的反映生态过程中的土壤抗蚀性变化过程。

English. 【Objective】 Soil anti-erodibility is an important parameter representing material cycle and energy flow in soil ecosystem. Study on dynamics of soil anti-erodibility in the abandoned cropland in Loess Hilly area so as to understand the change and effect evaluation during process of ecological restoration is of great importance. 【Method】 The research adopted interchangeable space-time method, selected the artificial shrubs at different times as objects and chose slope cropland and the plot grown with Platycladus orientailis as the control to analyze the change of soil anti-erodibility using statistic analysis. 【Result】 The results indicated that the soil anti-erodibility under erosive slope cropland owing to human activities was low. However, there was a significant improvement in soil anti-erodibility after planting shrub. The content of soil water-stable aggregates increased gradually and small aggregates and small microaggregates transformed into aggregates with much bigger diameter. EMWD, organic matter, aggregate state, aggregate degree, dispersion coefficient increased with years while soil structure deterioration rate dropped. In general, the improvement of Hippophae rhamnoides on soil anti-erodibility was better than that of Caragana korshinkii at the same age. Correlation analysis showed that there was a significant relationship among SAI, aggregate state, aggregate degree, microaggregates and phycio-chemical property, which can be used as indicators to reflect soil quality. SAI rose significantly, and increased by 497% in 25 a compared to slope cropland, while were only 69% and 52% of Hippophae rhamnoides and Platycladus orientailis, respectively.【Conclusion】 The results suggested that disturbance from human is a major cause of poor soil anti-erodibility. It is impossible to recover soil anti-erodibility by planting shrubs in erosive slope cropland in the Loess Hilly area, but there is a way to get the climax community. SAI can reflect effiectively the change of soil anti-erodibiity during ecological restoration.