克氏针茅(Stipa krylovii)草原土壤与优势植物碳氮含量对放牧强度的响应

Response of Carbon and Nitrogen in Soil and Dominant Plants to Grazing Intensity in Stipa krylovii Steppe

为探究不同放牧强度对土壤和植物的影响,本文以内蒙古阿巴嘎旗克氏针茅(Stipa krylovii)草原为研究区,通过野外采样和室内试验分析了禁牧(UG)、轻牧(LG)、中牧(MG)、重牧(HG)下土壤及优势植物克氏针茅、羊草(Leymus chinensis)和糙隐子草(Cleistogenes squarrosa)中有机碳、全氮含量和碳氮比及其相关性。结果表明:轻牧草场土壤有机碳和全氮含量显著高于其他放牧草场(P<0.05),而各放牧强度对土壤碳氮比均无显著影响;与禁牧相比,放牧降低了克氏针茅和羊草有机碳含量,却增加了它们的全氮含量;糙隐子草的有机碳和全氮含量均显著增加(P<0.05);土壤与植物的碳氮含量均无显著相关性。因此,从提高土壤与植物碳氮含量方面考虑,轻度放牧是克氏针茅草原适宜的放牧强度,禁牧并非合理的利用方式,但应避免重度放牧。

To investigate the effects of different grazing intensities on soil and plant,this study took Stipa krylovii steppe of Abaga Banner,Inner Mongolia as the study area.Through field sampling and laboratory experiments,the organic carbon,total nitrogen,carbon-nitrogen ratio and their correlations in soil and dominant plants Stipa krylovii,Leymus chinensis,and Cleistogenes squarrosa under grazing prohibition(UG),light grazing(LG),medium grazing(MG)and heavy grazing(HG)were analyzed.The results showed that the contents of soil organic carbon and total nitrogen in light grazing grassland were significantly higher than those in other grazing grasslands(P<0.05),but there were no significant effects of grazing intensity on soil carbon-nitrogen ratio.Compared with grazing prohibition,grazing decreased the organic carbon content of Stipa krylovii and Leymus chinensis,but increased their total nitrogen content.The contents of organic carbon and total nitrogen of Cleistogenes squarrosa were significantly increased(P<0.05).There was no significant correlation between soil and plant carbon and nitrogen content.Therefore,in terms of increasing the carbon and nitrogen content of soil and plants,light grazing is the appropriate grazing intensity for Stipa krylovii steppe,while grazing prohibition is not a reasonable way of utilization,but heavy grazing should be avoided.