宁夏草原植物叶片氮磷化学计量特征及其驱动因素

N、P循环控制着草地生态系统植物生长发育及群落结构和功能。为揭示宁夏草原植物N、P化学计量变化规律及其主要驱动因素,测定111个样地中的优势种植物409个样本叶片N、P含量,分析N、P化学计量特征、空间格局及其与气候因子(年均温度、年均降水量)的关系。结果表明,宁夏草原植物N、P含量的算数平均值分别为22.47和1.83 mg·g^-1,N/P为14.24,宁夏天然草地生长同时受N、P的限制;宁夏天然草地植物叶片N含量和N/P随纬度、年均温升高而增大,随海拔、年均降水量降低而增大,而叶片P含量随年均降水量升高而升高,N、P含量随经度升高而增大;空间分布和水热条件能够解释N、P含量及N/P方差的70.83%,这表明水热是宁夏天然草地植物叶片N、P化学计量特征的主要驱动因素,研究结果可为宁夏草原的管理和生产力的提升提供理论依据。

Factors influencing leaf nitrogen and phosphorus stoichiometry in plant species of Ningxia grasslands

Nitrogen (N) and phosphorus (P) cycles control plant growth and development, community structure and function of grassland ecosystems. In order to define patterns of change in leaf N and P stoichiometry in Ningxia grasslands, and their main driving factors, leaf N and P contents were determined for 409 dominant plant species at 111 sampling sites. The geographic distribution of leaf stoichiometry patterns was analyzed in relation to the climatic factors, mean annual temperature (MAT) and mean annual precipitation (MAP), as well as altitude and latitude of the sampling site. The arithmetic means for leaf N and P content of Ningxia grassland plants were 22.47 and 1.83 mg·g^-1, respectively, and the mean N∶P ratio was 14.24. The growth of Ningxia grassland plants was limited by N and P. Leaf N and N∶P ratio increased with the increasing latitude and MAT, and with decreasing altitude and MAP. Leaf P increased with increase in MAP, while leaf N and P both increased with increased longitude. Spatial distribution and hydrothermal conditions explained 70.83% of the variance for leaf N, leaf P and N∶P ratio, indicating that the hydrothermal environment is the main driving factor for the Leaf N and P stoichiometry of Ningxia grassland plants. The results provide a theoretical basis for the management and improvement of productivity in Ningxia grassland.