【作者】 苏少华；

【导师】 张兴昌；

【作者基本信息】 西北农林科技大学 ， 土壤学， 2008， 硕士

【摘要】 黄土高原地区的天然植被破坏殆尽,水土流失严重,经过20多年的植树造林,该地区植被覆盖度明显得到提高,生态条件逐步好转。论文采用时空替代法,研究了黄土高原丘陵区恢复过程中土壤磷素极其组成的变化特征,揭示各种植被影响下土壤磷素的变化规律,评价土壤磷素及其组成对植被恢复过程的响应机理,取得以下主要结论:土壤全磷、速效磷含量普遍偏低,无机磷所占比例较大,Ca-P为无机磷的主要形态,O-P均在检测限以下。无机磷组分含量及比例均保持顺序为Ca10-P>Ca8-P>Fe-P>Al-P>Ca2-P;有机磷占土壤磷素的比例较小,中活性Po是土壤有机磷的主要形态,有机磷组分含量及其比例均保持顺序为中活性Po>中稳性Po>高稳性Po>活性Po。不同人工植被土壤磷素水平明显低于耕作土壤,长期植被恢复降低了土壤全磷含量。根系强大的柠条和小叶杨土壤中,Ca2-P、Ca8-P、Al-P、活性Po和中活性Po含量总体处于较高水平,活性磷组分的含量相对较高,而浅根系植物铁杆蒿则处于相对较低的水平。随植被恢复年限的延长,土壤全磷和无机磷均呈明显下降趋势,而土壤有机磷则呈上升趋势,土壤无机磷各组分及其比例变化趋势基本与速效磷保持一致,有机磷中除高稳性Po保持相对稳定外,其他组分含量及其比例呈增长趋势。从坡顶到坡脚土壤全磷、无机磷、和速效磷呈线性增加,有机磷总体呈增加趋势,有机磷中,活性Po和中活性Po具有较高的活性,并呈向下坡位移动聚集的趋势,而中稳性Po和高稳性Po在坡面不同位置相对稳定。更多还原

【Abstract】 The intact vegetation resources in loess plateau was greatly damaged, which was accompanied with frangibility of ecological system, aggravation of land degradation and serious soil corrosion.After more than 20 years of vegetation afforestation, the area of land that was covered with plant and grass was increased, the ecological environment was gradually improved. Soil phosphorus composition in different vegetation type, restoration stage and on typical slope landform on local hill area in loess plateau was investigated. The phosphorus effect in these vegetation type, restoration stage and slope landform was also evaluated.(1)Phosphorus in soilTotal phosphorus and water-soluble phosphorus in soil was generally stayed in low level. Inorganic phosphorus took a large portion in total phosphorus composition, Ca-P was the main form of inorganic phosphorus, O-P was remained below the value that could be deteced. The content as well as proportion of inorganic phosphorus was changed according to the order as follows : Ca10-P>Ca8-P>Fe-P>Al-P>Ca2-P. Organic phosphorus took a small portion in total phosphorus composition, medium active organic phosphorus was the main form of organic phosphorus. The content as well as proportion of organic phosphorus was changed according to the order as follows : medium active organic phosphorus>medium stable organic phosphorus>high stable organic phosphorus>active organic phosphorus.(2)The effect of restored vegetation on soil phosphorusPhosphorus content in soil covered with artificial vegetation was obviously lower than that in cultivated soil, soil total phosphorus was decreased after long-term of vegetation afforestation. In soil covered with deep-root vegetation such as Caragana intermedia and Populus simonii, Ca2-P、Ca8-P、Al-P、the content of active organic phosphorus and medium active organic phosphorus was mainly stayed in high level, the content of active phosphorus was stayed in comparatively high level. In soil covered with shallow-root vegetation such as Artemisia gmelinii was stayed in comparatively low level.(3)The effect of time span in vegetation restoration on soil phosphorusAs number of years in vegetation restoration extended, the content of soil total phosphorus as well as organic phosphorus was greatly decreased, while the content of inorganic phosphorus was observed increased, the content and proportion of inorganic phosphorus kept almost the same. While that of organic phosphorus showed increased trend. High stable organic phosphorus was comparatively stable as time extended, the content and proportion of the rest inorganic and organic phosphorus was slightly decreased at the prophase of vegetation growth and was reached to climax value at metaphase of vegetation growth and was decreased again at anaphase of vegetation growth.(4)The distribution of soil phosphorus along the slopeSoil total phosphorus, inorganic phosphorus and water-soluble phosphorus was increased in linear function from slope top to slope toe, the medium active organic phosphorus and active organic phosphorus was in high activity,it moved to downwards of slope and accumulate there, there was not much change observed in medium stable organic phosphorus and high stable organic phosphorus along the slope.更多还原