[Background]:Plant community succession and soil nutrients change affects each other,and it is significant to research soil nutrient change in abandoned croplands with different years for us to understand plant community succession process.[Methods] Abandoned croplands at different years in the regions of Ruanliang and Yingliang in the Ordos Plateau,China,were selected (abandoned time was 1,6,10,15,and 20 years in Ruanliang;and 3,6,10,15 and 20 in Yingliang) to conduct field investigation for analyzing change of soil nutrients during vegetation succession.[Results] In the abandoned cropland in Ruanliang,except fluctuations of total carbon and total potassium,soil total nitrogen and total phosphorus increased gradually with increasing abandoned years,while total nitrogen and total phosphorus decreased with increasing soil depth.In the abandoned cropland in Yingliang,with increasing abandoned years,soil total carbon increased and then decreased generally;soil total nitrogen decreased and then increased at 0-10 cm soil layer,increased and then decreased at other soil layers;soil total phosphorus increased and then decreased at 0-30 cm soil layer,decreased and then increased at other soil layers;soil total potassium increased and then decreased at 0-10 cm soil layer,decreased at other soil layers.With increasing of soil depth,total carbon decreased in 20 year's abandoned cropland and natural vegetation,increased in other year's abandoned croplands;soil total nitrogen fluctuated in 6 year's abandoned cropland,decreased in other years' abandoned croplands;total phosphorus decreased and then increased in 10 years' abandoned cropland and natural vegetation,decreased in other year's abandoned croplands;soil total potassium did not show obvious changing trends.With the increasing abandoned years,soil C/N decreased,then increased,decreased finally in the abandoned cropland in Ruanliang and Yingliang.With the increasing soil depth,soil C/N decreased in natural vegetation,increased in other years' abandoned croplands in the abandoned cropland in Ruanliang;soil C/N increased in the abandoned cropland in Yingliang.[Conclusions] During vegetation succession,abandoned yeas and soil depth had significant effects on soil nutrients,and soil nutrient was higher in surface soil layers.The study provids scientific basis for vegetation restoration of abandoned cropland in the Ordos Plateau.%植物群落演替和土壤养分变化相互影响,探讨弃耕农田演替过程中土壤养分的变化,对理解植物群落的演替过程十分必要.以鄂尔多斯高原不同年限弃耕农田(软梁农田弃耕年限为1、6、10、15和20年,硬梁农田弃耕年限为3、6、10、15和20年)为对象,分析弃耕演替过程中土壤养分的变化特征.结果表明:对于软梁弃耕农田,除土壤全碳质量分数和全钾质量分数变化存在一定程度波动外,随弃耕年限增加,土壤全氮质量分数和全磷质量分数基本呈增加趋势;随土层深度增加,土壤全氮质量分数和全磷质量分数基本呈下降趋势.对于硬梁弃耕农田,随弃耕年限增加,土壤养分质量分数变化趋势较为复杂,土壤全碳质量分数总体呈先增加后减小趋势;0 ～ 10cm土层土壤全氮质量分数先减小后增加,其他土层先增加后减小;10～ 30 cm土层土壤全磷质量分数先增加后减小,其他土层先减小后增加;0 ～ 10 cm土层土壤全钾质量分数先增加后减小,其他土层减小.随着土层深度的增加,弃耕20年和自然植被的土壤全碳质量分数减小,其他弃耕年限的土壤全氮质量分数增加;弃耕6年的土壤全氮质量分数呈波动变化,其他弃耕年限的土壤全氮质量分数下降;弃耕10年和自然植被的土壤全磷质量分数先减小后增加,其他弃耕年限的土壤全磷质量分数下降;土壤全钾质量分数变化规律不明显.随弃耕年限增加,在软梁与硬梁弃耕农田中,土壤C/N均呈先减小后增加再减小的趋势.随着土层深度增加,软梁弃耕农田的土壤C/N在自然植被中呈下降趋势,在其他弃耕年限下呈增加趋势;硬梁弃耕农田的土壤C/N呈增加趋势.在弃耕演替过程中,弃耕年限与土壤深度对土壤养分质量分数存在显著影响,表层土壤养分质量分数较高.该研究可为鄂尔多斯高原弃耕农田的植被恢复提供科学依据.
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