内蒙古典型草地不同时期土壤及植被养分评价

目的]研究内蒙古典型草地不同时期土壤及植被营养状况的差异及变化特点，为内蒙古典型草地的合理利用、退化草地的恢复治理以及畜牧业的可持续发展提供参考。方法]从内蒙古不同地区典型草原选取8个监测点，包括G1（鄂温克草原，温性草甸草原，呼伦贝尔市）、G2（乌拉特草原，荒漠草原，巴彦淖尔市）、G3（天然草滩，乌兰察布市）、G4（辉腾锡勒草原，五花草甸草原，乌兰察布市）、G5（科尔沁草原，温性草甸草原，通辽市）、G6（人工牧草种植地，赤峰市）、G7（乌拉特草原，荒漠草原，包头市）、G8（格根塔拉草原，荒漠草原，乌兰察布市）；于2020年牧草返青期、旺盛期、枯萎期分别从不同监测点样方中取0~20 cm土层土样及植物样品地上部分，测定土壤和植物中的常规养分含量；利用主成分分析法计算不同监测点不同时期土壤及植被营养水平的综合得分并排序。结果]返青期、旺盛期、枯萎期土壤全氮含量均为G4监测点（辉腾锡勒草原）最高，极显著（P<0.01）高于其他监测点；旺盛期、枯萎期G7监测点（包头市境内乌拉特草原）最低。3个时期土壤有效磷含量均为G6监测点（人工牧草种植地）最高，显著（P<0.05）或极显著（P<0.01）高于其他监测点。3个时期土壤有机质含量均为G4监测点（辉腾锡勒草原）最高，极显著（P<0.01）高于其他监测点，G7监测点（包头市境内乌拉特草原）最低。返青期G6监测点（人工牧草种植地）的植被氮、磷、钾含量均为最高，极显著（P<0.01）高于其他监测点。旺盛期G8监测点（格根塔拉草原）的植被氮、钾含量最高，G6监测点（人工牧草种植地）的植被磷含量最高。枯萎期G3监测点（乌兰察布市境内天然草滩）的植被氮、磷含量最高，G4监测点（辉腾锡勒草原）的植被钾含量最高。3个时期植被粗纤维含量均是G5监测点（科尔沁草原）最高，G4监测点（辉腾锡勒草原）最低。土壤营养状况评分为：G4监测点（辉腾锡勒草原）3个时期评分均较高，G7监测点（包头市境内乌拉特草原）3个时期评分均最低；植被营养状况评分为：G2监测点（巴彦淖尔市境内乌拉特草原）及G6监测点（人工牧草种植地）返青期>旺盛期>枯萎期，其余监测点均是旺盛期>返青期>枯萎期。结论]内蒙古典型草原的土壤及植被养分含量存在明显的时空差异。总体来看，草甸草原返青期、旺盛期、枯萎期土壤中养分综合评分较高，荒漠草原3个时期评分较低；不同草原类型的植被养分综合评分在旺盛期较高，枯萎期较低。

Nutrient Contents Evaluation of Soil and Vegetation in Typical Grasslands in Inner Mongolia at Different Periods

Objective] This study was conducted to investigate the differences and changing characteristics of nutrient contents of soil and vegetation in typical grasslands in Inner Mongolia at different periods, and to provide references for the rational utilization of typical grasslands, the restoration and management of degraded grasslands, and the sustainable development of animal husbandry in Inner Mongolia. Method] A total of eight monitoring points were selected from the typical grasslands in different regions of Inner Mongolia, including G1 （Ewenki Grassland, temperate meadow grassland, Hulun Buir City）, G2 （Urad Grassland, desert grassland, Bayannur City）, G3 （natural grassland, Ulanqab City）, G4 （Huitengxile Grassland, tessellated meadow grassland, Ulanqab City）, G5 （Horqin Grassland, temperate meadow grassland, Tongliao City）, G6 （artificial forage planting site, Chifeng City）, G7 （Urad Grassland, desert grassland, Baotou City), and G8 （Gegentala Grassland, desert grassland, Ulanqab City）. In the year of 2020, the soil samples of 0-20 cm soil layers and the above-ground parts of plant samples were taken at different monitoring points during the re-greening, vigorous and withering periods of forage, respectively. The contents of the conventional nutrients in the soil and plant samples were determined. The comprehensive scores of soil and vegetation nutrient levels at different monitoring points at different periods were calculated and sorted by using the principal component analysis method. Result] The content of soil total nitrogen （STN） in G4 monitoring point （Huitengxile Grassland) during the re-greening, vigorous and withering periods was the highest, which was extremely significantly （P<0.01） higher than that in the other monitoring points; while G7 monitoring point （Urad Grassland within the boundaries of Baotou City） had the lowest STN at both vigorous and withering periods. The highest content of soil available phosphorus （SAP） was seen over the three observed periods in G6 monitoring point （artificial forage planting site）, which was significantly （P<0.05） or extremely significantly （P<0.01） higher compared with the other monitoring points. Over the three observed periods, the content of soil organic matter （SOM） in G4 monitoring point （Huitengxile Grassland） was the highest, which was extremely significantly （P<0.01） higher than that in the other monitoring points; while G7 monitoring point （Urad Grassland within the boundaries of Baotou City） had the lowest SOM. At the re-greening period, the contents of plant nitrogen, phosphorus and potassium in G6 monitoring point （artificial forage planting site） were the highest, which were extremely significantly （P<0.01） higher than those in the other monitoring points. At the vigorous period, the highest contents of plant nitrogen and potassium were observed in G8 monitoring point （Gegentala Grassland）, while the highest content of plant phosphorus was found in G6 monitoring point （artificial forage planting site）. At the withering period, G3 monitoring point （natural grassland within the boundaries of Ulanqab City） had the highest contents of plant nitrogen and phosphorus, while G4 monitoring point （Huitengxile Grassland） had the highest content of plant potassium. Over the three observed periods, the highest and the lowest contents of plant crude fiber were found in G5 monitoring point （Horqin Grassland） and in G4 monitoring point （Huitengxile Grassland）, respectively. For the score of soil nutrient status over the three observed periods, G4 monitoring point (Huitengxile Grassland) had higher rankings, while G7 monitoring point （Urad Grassland within the boundaries of Baotou City） showed the worst performance. As for the score of plant nutrient status, both G2 monitoring point （Urad Grassland within the boundaries of Bayannur City） and G6 monitoring point （artificial forage planting site） had the highest rankings at the re-greening period, followed by the vigorous period and the withering period; while all the other monitoring points exhibited the best performance in the vigorous period, followed by the re-greening period and the withering period. Conclusion] There were obvious seasonal and regional variations in nutrient contents of the soil and vegetation in typical grasslands in Inner Mongolia. On the whole, the meadow grassland had higher comprehensive scores regarding soil nutrient contents during the re-greening, vigorous and withering periods, while the desert grassland had lower comprehensive scores across the three observed periods. Furthermore, the comprehensive scores of vegetation nutrient of different grassland types were generally higher at the vigorous period and lower at the withering period.