Effects of reclamation of rehabilitated cropland on soil properties and its spatial variation on the Loess Plateau of China | 黄土高原退耕地复垦对土壤理化性状及空间变异特征的影响

Chinese. 明确复垦措施对黄土高原退耕地土壤理化性质的影响，并揭示其空间变异特征，为评价退耕地复垦对当地生态环境的影响提供帮助，并为相关政府决策提供参考。在实地调查和取样分析的基础上，使用经典统计学和地统计学相结合的方法，以山西省广灵县退耕6年后复垦的典型坡耕地为对象，对比研究了复垦前(2007-04)和复垦2年后（2009-05）表层(0～15 cm)土壤理化性质的差异及空间变异特征。与复垦前相比，复垦2年后表层土壤有机质、全氮、全磷以及碱解氮、速效磷和速效钾含量分别降低了38%，11%，15%，24%，81%和8%，而体积质量则降低了7%；研究区土壤养分属中等变异，而土壤体积质量属弱变异；复垦前土壤性质的合理采样数依次为有机质速效磷碱解氮速效钾全氮全磷体积质量，复垦后略有变化；土壤养分和体积质量的变化主要是随机性因素（人为活动）作用的结果，且复垦措施可使土壤理化性质的空间相关性减弱并朝均一化方向发展，从而明显影响土壤养分和体积质量的空间分布特征。退耕地复垦可使土壤理化性状迅速恶化，使其空间相关性减弱和朝均一化方向发展，因此应予以避免。

English. The effects of reclamation on the change and spatial variation of soil physicochemical properties in rehabilitated sloping land on the Loess Plateau of China were studied in this research. A reclaimed sloping land which was rehabilitated for six years was selected as experimental site in Guangling County of Shanxi Province. In the site, the top 15 cm soil was sampled before and after two years of reclamation, and then the soil properties including organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus, available potassium, and bulk density were measured. The experimental data was analyzed by classic statistical and geostatistical method. The content of organic matter, total nitrogen, total phosphorus, available nitrogen, available phosphorus, available potassium, and bulk density two years after reclamation-decreased by 38%, 11%, 15%, 24%, 81%, 8% and 7%, respectively; the soil bulk density had a weak variation, and the soil nutrients had a moderate variation; the descending order of reasonable sampling number of soil properties before reclamation was organic matteravailable phosphorusavailable nitrogenavailable potassiumtotal nitrogentotal phosphorusbulk density, and this order had a minor variation after reclamation; the distribution and variation of soil properties was mainly influenced by random factors including man-made factors rather than structural factors, and the reclamation practice increased the uniformity and decreased the spatial variation of soil physicochemical properties. The reclamation of rehabilitated cropland could negatively affect the soil properties, and change their spatial variation characteristics remarkably. Therefore the reclamation practices should be strictly prohibited by local governments to protect the environment and fragile ecosystem on the Loess Plateau of China.