黄土高原典型草原优势种植物及其根际土壤化学计量对降雨变化的响应

为探讨黄土高原典型草原优势种植物及其根际土壤化学计量对不同降水量的响应，以宁夏固原云雾山封育20年典型草原为研究对象，利用遮雨棚技术模拟了3个不同的降水梯度(自然降水量的50%、100%和150%),测定了优势种长芒草(Stipa bungeana)、星毛委陵菜(Potentilla acaulis)和白莲蒿(Artemisia sacrorum)的地上、地下全碳(TC)、全氮(TN)、全磷(TP)含量及其根际土壤有机碳(RSOC)、全氮、全磷含量，分析了各个优势种及其根际土壤化学计量及其之间的相关性。结果表明：(1)3个优势种地上、地下总C含量、地上N含量均在50%降水下较高，星毛委陵菜地上和地下P含量及地上、地下总P含量均在100%降水处理下最高。(2)50%降水与150%降水处理相比较，长芒草地上C/N、C/P及白莲蒿、星毛委陵菜地下C/P均有显著差异(P<0.05),150%降水处理下优势种N/P显著高于50%降水处理(P<0.05)。(3) 3个优势种根际土壤C、N含量高于黄土高原土壤C、N含量且150%降水处理下根际土壤C含量显著高于50%降水处理(P<0...

Responses of dominant species and rhizosphere soil stoichiometry to rainfall in typical steppe of the Loess Plateau

In order to explore the response of dominant species and rhizosphere soil stoichiometric of typical grassland in the Loess Plateau to different precipitation treatments, the typical grassland fenced for 20 years in Yunwu Mountain, Guyuan, Ningxia was selected as the research object, using shelter technology to simulate three different precipitation gradients (50%, 100% and 150% of natural rainfall). The content of total carbon (TC), total nitrogen (TN), total phosphorus (TP), rhizosphere soil organic carbon (RSOC), total nitrogen, and total phosphorus in the aboveground and underground of the dominant species Stipa bungeana, Potentilla acaulis and Artemisia sacrorum were analyzed, The correlations between the stoichiometry of each dominant species and rhizosphere soil stoichiometry were analyzed. The results showed that (1) the above and below ground total C content and above ground N content of the three dominant species were all higher under 50% precipitation, while the above and below ground P content and total P content in Potentilla acaulis were the highest under 100% precipitation. (2) Compared with the treatment of 50% and 150% precipitation, the aboveground C/N, C/P of Stipa bungeana and the underground C/P of Potentilla acaulis and Artemisia sacrorum were significantly different (P<0.05); the N/P of dominant species under 150% precipitation treatment was significantly higher than that under 50% precipitation (P<0.05). (3) The contents of C and N in the rhizosphere soil of the three dominant species were higher than those in the Loess Plateau soil, and the content of C in the rhizosphere soil under 150% precipitation was significantly higher than that under 50% precipitation (P<0.05). Increasing precipitation treatment indicated higher C/N and C/P of the rhizosphere soil of the dominant species than decreasing precipitation treatment, but with smaller changes in N/P. (4) Under 50% precipitation treatment, there was a negative correlation between the N content and the C content in the rhizosphere soil of Artemisia sacrorum and Potentilla acaulis, both above and below ground (P<0.05). Under 100% precipitation treatment, the total C, N, P contents of the dominant species were strongly correlated with the C, N, and P contents of the rhizosphere soil (P<0.05). Under 150% precipitation, the underground C content of dominant species was negatively correlated with its N content in rhizosphere soil. (5) The absolute value of negative correlation coefficient between N content in rhizosphere soil and underground N content of the three dominant species was greater than that between P content in rhizosphere soil and underground P content. The research results will provide a scientific reference for understanding of the material cycle of typical grassland ecosystems in the Loess Plateau and judgment of vegetation nutrient limitations.