五台山亚高山-高山草甸群落多样性和碳氮磷化学计量特征

为了探究连续海拔梯度上亚高山-高山草甸群落多样性、碳氮磷化学计量特征及其环境适应策略，以五台山南坡自然分布的亚高山-高山草甸群落为研究对象，沿海拔梯度(2 201~3 011 m)设置9个样地，采用相关性分析、偏冗余分析(pRDA)的方法，分析亚高山-高山草甸群落多样性和碳氮磷化学计量特征及其与环境因子的关系. 结果表明:在五台山南坡2 201~3 011 m海拔范围内，亚高山-高山草甸群落的Patrick指数、Shannon-Wiener指数、Simpson指数、Pielou指数平均值分别为11、2.15、0.87、0.93. 随着海拔的升高，Patrick指数、Shannon-Wiener指数、Simpson指数均呈显著下降趋势，而Pielou指数变化不显著. 群落TC、TN、TP含量平均值分别为461.19、23.32、1.96 mg/g，C∶N、C∶P和N∶P平均值分别为19.99、242.17、12.10. 与全球尺度和草地生态系统区域尺度的研究相比，该区域草甸群落具有相对稳定的TC含量，以及TN、TP含量高和N∶P低的特点，群落水平下相对较低的N∶P(<14)说明草甸群落植物生长更倾向于受氮元素的限制. 随着海拔升高，群落TC含量、C∶N、C∶P沿海拔梯度均呈显著上升趋势，而群落TN、TP含量均呈显著下降趋势，群落N∶P变化不显著. 在海拔梯度上，群落碳氮磷化学计量特征存在差异性，在一定程度上说明了草甸群落对海拔生境的不同适应策略. 偏冗余分析结果表明，环境因子(海拔和土壤因子)分别解释了亚高山-高山草甸群落多样性和碳氮磷化学计量特征总变化的70.8%和67.8%，海拔因子的解释贡献率大于土壤因子. 研究显示，海拔和土壤因子对五台山亚高山-高山草甸群落多样性和碳氮磷化学计量变化特征存在显著影响，其中海拔因子的影响尤为突出. 

Community Diversity and C,N and P Stoichiometric Characteristics of Subalpine-Alpine Meadows in Wutai Mountain

In order to explore the community diversity, carbon, nitrogen and phosphorus stoichiometric characteristics and environmental adaptation strategies of subalpine-alpine meadows along a continuous altitude gradient, the naturally distributed upland subalpine-alpine meadow communities on the southern slope of Wutai Mountain were evaluated. Nine sites were sampled in the altitude range of 2201-3011 m, and correlation analysis and partial redundancy analysis (pRDA) were used to analyze the community diversity, the carbon, nitrogen and phosphorus stoichiometric characteristics, and their relationships with environmental factors. The results showed that the average Patrick index, Shannon-Wiener index, Simpson index, and Pielou index were 11, 2.15, 0.87 and 0.93, respectively. With increasing altitude, Patrick index, Shannon-Wiener index, and Simpson index showed significant downwards trends, while the Pielou index did not change significantly. The TC, TN and TP contents of the subalpine-alpine meadow community were 461.19, 23.32 and 1.96 mg/g, respectively, and the average C∶N, C∶P and N∶P ratios of the subalpine-alpine meadow community were 19.99, 242.17 and 12.10, respectively. Compared with the results of the global scale and grassland ecosystem regional scale, the subalpine-alpine meadow community was characterized by a relatively stable TC, a higher TN and TP, and lower N∶P. The lower N∶P (<14) at the community level indicated that the plant growth in the subalpine-alpine meadow community was more limited by N. Along the altitudinal gradient, the TC content, C∶N ratio and C∶P ratio significantly increased, while the TN and TP contents significantly decreased with increasing elevation, and the N∶P ratio did not change significantly. In addition, the carbon, nitrogen and phosphorus stoichiometric characteristics among the subalpine-alpine meadow communities had some differences, which to some extent indicated the different adaptation strategies of mountain meadow communities to altitudinal habitats. The pRDA results showed that environmental factors (altitude and soil factors) explained 70.8% and 67.8% of the variation in the community diversity and in the carbon, nitrogen and phosphorus stoichiometric characteristics of the subalpine-alpine meadow community, respectively. Furthermore, altitude was more important than the soil factors in explaining the community diversity and the carbon, nitrogen and phosphorus stoichiometric characteristic variation. Our results indicate that altitude and soil factors have significant effects on the variation of the community diversity and the carbon, nitrogen and phosphorus stoichiometric characteristics in the subalpine-alpine meadow community of Wutai Mountain, and altitude is particularly prominent.