不同放牧强度对荒漠草原牧草微量元素和营养成分的影响

目的] 探明不同放牧强度下荒漠草原牧草和主要优势牧草的微量元素和营养成分含量的变化特征。方法] 在内蒙古自治区鄂尔多斯市鄂托克旗荒漠草原不同放牧强度区域（适度放牧区、禁牧区和重度放牧区）进行连续3年野外调查和室内检测,综合分析不同放牧强度对荒漠草原牧草以及优势牧草微量元素和营养成分含量的影响。结果] 适度放牧区优势牧草无芒隐子草和蒙古韭的硒含量显著（P<0.05）高于禁牧区和重度放牧区,适度放牧区牧草铜含量显著（P<0.05）高于禁牧区和重度放牧区,且禁牧区和重度放牧区牧草硒和铜含量近持平或低于该地区安全含量标准;适度放牧区优势牧草蒙古韭的铁含量显著（P<0.05）高于禁牧区;重度放牧区牧草镁含量显著（P<0.05）高于禁牧区和适度放牧区,且超该地区安全含量标准;适度放牧区优势牧草短花针茅、无芒隐子草和蒙古韭钠含量显著（P<0.05）高于禁牧区和重度放牧区;适度放牧区牧草粗蛋白质、粗脂肪、粗灰分、磷和钙的含量分别高于禁牧区牧草60.71%、69.00%、47.62%、28.57%和347.85%;适度放牧区牧草粗纤维、中性洗涤纤维和酸性洗涤纤维含量比禁牧区分别降低13.93%、24.80%和6.35%;适度放牧区优势牧草短花针茅粗蛋白质含量高于禁牧区11.50%,优势牧草无芒隐子草粗脂肪、粗灰分和钙含量分别高于禁牧区24.12%、87.56%和116.86%;适度放牧区蒙古韭钙含量比禁牧区高出24.03%。结论] 由于长期禁牧和过度放牧导致鄂托克旗荒漠草原迁入欠硒、欠铜草地。只有在适度放牧强度下,草地牧草才能保持应有的优良品质。

Effects of Different Grazing Intensities on Trace Elements and Nutritional Components of Forage Grasses in Desert Steppe

Objective]To explore the variation characteristics of trace elements and nutrients contents of forage grasses and main dominant forage grasses in desert steppe under different grazing intensities.Method]Field investigations were conducted in areas with different grazing intensities(moderate grazing area,no-grazing area and heavy grazing area)in desert steppe in Otog Banner,Ordos City,Inner Mongolia Autonomous Region for 3 consecutive years.Combined with laboratory analysis,the effects of different grazing intensities on the contents of trace element and nutrient of forage grasses and three kinds of main dominant forage grasses(Cleistogenes songorica,Allium mongolicum,Stipa breviflora)in desert steppe were assessed.Result]The selenium content of Cleistogenes songorica and Allium mongolicum as well as the copper content of forage grasses in moderate grazing area were significantly(P<0.05)higher than those in no-grazing area and heavy grazing area,and the selenium and copper contents of forage grasses in no-grazing area and heavy grazing area were nearly equal to or lower than the safe content standard in this region.The iron content of Allium mongolicum in moderate grazing area was significantly(P<0.05)higher than that in no-grazing area.The magnesium content of forage grasses in heavy grazing area was significantly(P<0.05)higher than that in no-grazing area and moderate grazing area,and exceeded the safety content standard in this region.The sodium content of Stipa breviflora,Cleistogenes songorica and Allium mongolicum in moderate grazing area was significantly(P<0.05)higher than that in no-grazing area and heavy grazing area.The contents of crude protein,crude fat,crude ash,phosphorus and calcium of forage grasses in moderate grazing area were higher than those in no-grazing area by 60.71%,69.00%,47.62%,28.57%and 347.85%,respectively.The contents of crude fiber,neutral detergent fiber and acid detergent fiber of forage grasses in moderate grazing area were lower than those in no-grazing area by 13.93%, 24.80% and 6.35%, respectively. The crude protein content of Stipa breviflora in moderate grazing area was higher than that in no-grazing area by 11.50%. The contents of crude fat, crude ash and calcium of Cleistogenes songorica in moderate grazing area was higher than those in no-grazing area by 24.12%, 87.56% and 116.86%, respectively. The calcium content of Allium mongolicum in moderate grazing area was higher than that in no-grazing area by 24.03%.Conclusion] Due to the long-term grazing prohibition and overgrazing, the selenium and copper deficient grassland moves into the desert steppe in Otog Banner. Only by moderate grazing intensity can forage grasses maintain good quality.